Browse Topic: Axles

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Directional Vehicle Control by Steering the Third Axle to Provide Redundancy for Steer-by-Wire Systems and Highly Autonomous Vehicles02-13-03-00159/25/2020
A way of providing steering redundancy for highly autonomous vehicles or vehicles equipped with steer-by-wire systems by steering the rear axle for directional control of the vehicle has been previously proposed. In this study, we further investigate and improve on that concept and validate it through simulation and experimental testing on a vehicle. Consequently, we show that in the case of failure of primary front axle steering system, the vehicle controller steering command (in the case of autonomous driving) or the driver’s steering command (in the case of a steer-by-wire system) can be mathematically manipulated to generate a steering input at the rear axle, which results in the same yaw rate response as if the vehicle was steered from the front, and thus providing a way to control the vehicle should a failure occur in the primary steering system.
Nhila, Amine, Williams, Dan E.
Modeling and Analysis of a Heavy Vehicle with Self-Steering Axle02-13-01-00034/21/2020
Commercial vehicles often incorporate self-steering axles to meet the axle load requirements while providing improved maneuverability, reduced off-tracking, and reduced tire and pavement wear. Market forces promote the design of more efficient self-steering axle products with reduced weight and more features. Manufacturers also work to differentiate their products through unique designs and new concepts. Traditional design methods for self-steering axles include empirical and trial-and-error methods to set the steering mechanism design parameters based on known design baselines and prior experience. For innovative new concepts that are too far from the traditional designs, it is desirable to have alternative ways for evaluating the expected performance. This article introduces a reduced-order model that allows the rapid analysis of the steering dynamic behavior of self-steering axles. The model combines a pendulum-like lateral stiffness model with the axle steering dynamics which are then coupled to suitable reduced-order models for tractor-trailer combinations on which the self-steering axle can be mounted. The proposed model is shown to capture the shimmy behavior of the self-steering axle using phase portraits of the coupled nonlinear system. The model provides a way to identify the important stiffness and damping parameters of steering axle design concepts that are not yet sufficiently developed, and therefore the details required for full multi-body dynamic analysis are not available.
Delorenzis, Damon, Ayalew, Beshah
Setting Preload in Heavy-Duty Wheel BearingsJ2535_201910 (Current)10/7/2019
This SAE Recommended Practice applies to the four primary, large volume applications in the class 7-8 heavy-duty market place, as specified in SAE J1842: a “N” trailer axle b “R” powered rear axle c “FF / FG” nonpowered front axle d “P” trailer axle This document applies to on-highway applications. It is not applicable to those applications that exceed the GAWR ratings or the load line restrictions listed in columns “A,” “B,” and “C” of Table 1. Load lines are measured from the inboard bearing cup backface as shown in 3.4. This document establishes preload force values only. The methodology to obtain these force values must be determined by the fastener supplier and/or axle assembler. This document reviews the bearing system. It is NOT intended to prescribe (new or existing) axle and/or hub manufacturers’ ratings and/or specifications.
Truck and Bus Wheel Committee
The Improvement Brake’s Qualities of Vehicle by Developing the Method of the Choosing Frictional Pairs of the Brakes Mechanisms2019-01-21459/15/2019
One of the reasons for the large number of road accidents on highways in Ukraine [1] is the instability of the braking properties due to the unstable characteristics of the brake mechanisms’ friction pairs. The manufacturer produces new automobiles with installed brake pairs (brake pads and their counter bodies), which have passed long-term tests for the stability of the friction coefficient and braking forces distribution of between the axles. This ensures the compatibility of the friction pairs characteristics for front and rear brake mechanisms according to the criteria of heat resistance. During operation, instead of worn-out brake pads, brake discs and drums, drivers can purchase new ones, manufactured as spare parts. However, in the well-known literature there are no methods that allow to check the compatibility of the friction pairs characteristics for front and rear brake mechanisms according to the criteria of heat resistance. In the article a method for choosing a set of friction pairs of brake mechanisms for passenger car during operation is proposed. Assessment of the compatibility of the friction pairs characteristics for front and rear brake mechanisms was carried out according to the criteria of heat resistance.
Podrigalo, Mikhail, Klets, Dmytro, Kholodov, Mykhailo, Bogomolov, Viktor, Turenko, Anatoliy, Molodan, Andrii, Rudzinskyi, Volodymyr, Tarasov, Yurii, Mykolai, Aloksa, Hatsko, Vasyl
Stability of Wheel Tractors during Braking2019-01-21429/15/2019
The dynamic distribution of normal reactions between the axles of the wheeled tractor has a significant impact on the stability against skidding and the wheeled tractor braking effectiveness. At the same time, the clarification of the normal reactions distribution between the axles allows to choose more rational braking forces distribution between the axles. It is shown that the best way to ensure the highest braking efficiency is the braking mode when the rear wheels of the tractor are at the blocking limit. An assessment of the expediency of installing brake mechanisms on only one axle of the tractor was made. The increase of braking efficiency of wheeled tractors with all brake wheels provided that they ensure directional stability is considered. The laws of braking forces distribution between the axles of wheel tractors for different sequence of wheels locking are determined. Using the method of partial accelerations an improved method for estimating the effect of a brake system on the stability of wheeled tractor is proposed. The criterion in the form of angular acceleration in the road plane ώz, by the value and sign of which one we can estimate the operational stability of the brake mechanisms has obtained.
Podrigalo, Mikhail, Kholodov, Mykhailo, Klets, Dmytro, Dubinin, Yevhen, Savchenkov, Borys, Koryak, Alexander, Rudzinskyi, Volodymyr, Viktoriia, Zadorozhnia, Polianskyi, Oleksandr
Analysis of the Tractor-Trailer Dynamics during Braking2019-01-21449/15/2019
The intensive development of tractor-building industry in the world has led to the widespread use of wheeled tractors and tractor trains in transportations on public highways. This requires an increase of engine capacity and speed of tractor trains, as well as strict demands for their braking systems. The formation of the necessary braking properties of wheeled tractors and tractor trains on their basis should be carried out at the design phase, taking into account a wide range of aggregated machines and tools. Blocking the wheels of the trailer with different sequence of their blocking and blocking the wheels of the tractor has significant impact on the total braking force, deceleration and stability of the tractor train. It is advisable to take this into account when modeling the braking process of a tractor train. The article deals with the braking dynamics of the tractor train and the impact of the dynamic distribution of normal reactions between the axles on the brake properties of the tractor train. The mathematical model of the braking process of the tractor-trailer train (consisting of a wheeled tractor and a two-axle trailer at the limit of blocking the wheels) has been obtained. The coefficients of the total braking force distribution between the to the front and rear axles of the tractor, front and rear axles of the trailer, ensuring the directional stability of the tractor-trailer train, have been determined.
Podrigalo, Mikhail, Klets, Dmytro, Kholodov, Mykhailo, Klimenko, Valeriy, Rudzinskyi, Volodymyr, Kholodov, Anton
Improvement of Hypoid Gears Dynamics Performance Based on Tooth Contact Optimization2019-01-15636/5/2019
The meshing noise of hypoid gear has a significant influence on driving axle system. It should be strictly controlled in order to reduce the whole vehicle noise. Meshing internal excitation of hypoid gear is a main source of vibration noise, closely connected with geometrical shape and meshing status. There is no comprehensive analysis on the impact of various contact patterns on vibration noise in previous studies. Therefore, the method for controlling contact characteristics of hypoid gears is studied in this paper, which includes adjusting the position and length of contact pattern, direction of contact trace and the theoretical transmission error. Also, a non-linear dynamic model with multi-freedom for the hypoid gear pair of the driving axle is established to evaluate the dynamic response of the gear pair. Then an example was carried out to improve the dynamic characteristic of hypoid gears by tooth profile modification. It is proved that the dynamic transmission error and mesh force can be reduced effectively through reasonably controlling the contact characteristic parameters of the gear pair. This complete process of tooth profile design, dynamic analysis and tooth contact characteristic adjustment is therefore demonstrated to be an effective approach to the optimization of hypoid gear design in order to acquire good vibration and noise performance of the driving axle.
Zhang, Weiqing, Wang, Yawen, Lin, Chia-Ching, Lim, Teik, Guo, Xiaodong, Wang, Kan, Zheng, Yong
ABS Exciter Ring Location StandardizationJ1730_201902 (Historical)2/11/2019
This SAE Recommended Practice establishes the Antilock Brake System [ABS] sensor interface and envelope dimensions for standardizing the location of the ABS rings mounted on the inner end of spoke wheels, hubs and hub-rotor assemblies on the following axle designations. a FF b FL c FC d FH e L f R g U h W j N k P
Truck and Bus Wheel Committee
Increase of Stability for Motor Cars in Service Braking2018-01-188010/5/2018
New solutions for actual problems of determination the efficient distribution of braking forces between the axles of the vehicle, and the stability and drivability of two-axles vehicles at service braking are received in the thesis. It permitted for the first time to determine the Law of distribution of the braking forces between the axles, that ensuring straight-running stability of two-axle vehicle at service braking, to obtain the ideal characteristics for the braking system of two-axle vehicle at service braking and to determine possible values for the distribution of braking force on the front axle. The drivability criterion at service braking obtained further development; it is offered to use boundary at gripping front or rear wheels angular vehicle acceleration on the road. The application of the stability coefficient as one of the criteria for service braking efficiency allowed to determine the ideal, as for preserving the road-holding ability, Law of distribution of the braking forces between the axles. Despite the idea, if the vehicle deceleration is increased at service braking, the ideal coefficient of braking force distribution on the front axle should be decreased, but not be increased. At small decelerations, the given coefficient can be equal to one (rear wheels are not braked), and at the maximum decelerations - we should take into account the values that correspond to retain the front and rear wheels on the blocking limit. The area of rational values of the coefficient of braking force distribution on the front axle, limited by the curves of the ideal distribution of braking forces at service braking and limit values of the adhesion coefficient, and by straight line of the ideal distribution of braking forces at emergency braking are determined. The limit values of the vehicle deceleration at service braking are determined. If the limit values are lower than the given ones, it is necessary to carry out braking only with the front wheels brakes. The obtained ideal characteristics of the two-axles braking system allow to estimate braking dynamics at emergency and service braking on roads with different coefficient of adhesion. With constant distribution of braking forces between the axles the deceleration area boundaries in which the vehicle can retain the road-holding ability at service braking are defined. To assess the impact of disturbances on the road-holding ability of the vehicle at service braking, a new criterion, the coefficient of disturbing action is offered. If the criterion value does not exceed the stability coefficient, the vehicle is stable, otherwise it loses its stability.
Podrigalo, Mikhail, Turenko, Anatoliy, Bogomolov, Viktor, Klets, Dmytro, Sergiyenko, Oleg, Karpenko, Volodymyr, Gritsuk, Igor V., Turenko, Oleksandr, Korobko, Andrii, Bulgakov, Nickolay, Boboshko, Oleksandr
Improvement of the Assessment Methods for the Braking Dynamics with ABS Malfunction2018-01-188110/5/2018
The bulk of automobiles are equipped with ABS currently. Having of automatic devices that prevent vehicle wheels from locking and skidding does not require consideration of the normal reactions on the front and rear vehicle axles wheels’ changes dynamics. However, ABS malfunction is possible for various reasons, and in this case the braking system must provide the safety vehicle braking. To provide this, it is necessary to return to the problem of choosing the rational braking forces distribution between the wheels of the front and rear axles. Analysis of known methods for determining the rational choice of the braking forces distribution between the axes made it possible to reveal a number of inaccuracies and contradictions, to which the following notes can be attributed: traditionally it is determined the limiting forces distribution on the wheels’ adhesion with the road in case of emergency braking, and according to its braking moments distribution, which does not take into account the influence of inertial masses, which are applied to the wheels; when the normal reactions on wheels and their redistribution between the axles are determining, the changing in the point of application of the braking force, during the wheels' locking, is not taking into account (when the wheels are unblocked, the braking force is applied to the wheel axle, and when the wheels are locked, the braking force is applied to the contact spot of the wheels with the road). The article deals with analytical expressions which allow to make a rational choice of the brake moments distribution between the front and rear wheels, taking into account the inertial masses of a powertrain. It is shown that the known law of the ideal distribution of tangential reactions between the axes corresponds to the automobile braking with all blocked wheels. If it is necessary to bring simultaneously the front and rear wheels to the blocking limit, then it will be necessary to choose another law of braking forces distribution between the axles, at which the front brakes are weakened and the rear brakes are strengthened. Simultaneous bringing to the blocking limit the front and rear wheels does not prevent locking of the rear wheels first. It is determined that in case of the ABS failure on the rear wheels and the normal work of the ABS on the front wheels, makes it possible to improve the stability of the automobile (compared to the ABS failure on the all wheels) by increasing the normal load on the rear wheels. The recommendations, which are given, can be useful at the development of automobile braking systems. They will allow increasing safety of automobile braking not only at АВS malfunction, but also at service braking when АВS is not working.
Podrigalo, Mikhail, Klets, Dmytro, Sergiyenko, Oleg, Gritsuk, Igor V., Soloviov, Oleh, Tarasov, Yuriy, Baitsur, Maksym, Bulgakov, Nickolay, Hatsko, Vasyl, Golovan, Andrii, Savchuk, Volodymyr, Ahieiev, Maksym, Bilousova, Tetiana
Eleven Instrumented Motorcycle Crash Tests and Development of Updated Motorcycle Impact-Speed Equations2018-01-05174/3/2018
Eleven instrumented crash tests were performed as part of the 2016 World Reconstruction Exposition (WREX2016), using seven Harley-Davidson motorcycles and three automobiles. For all tests, the automobile was stationary while the motorcycle was delivered into the vehicle, while upright with tires rolling, at varying speeds. Seven tests were performed at speeds between 30 and 46 mph while four low-speed tests were performed to establish the onset of permanent motorcycle deformation. Data from these tests, and other published testing, was analyzed using available models to determine their accuracy when predicting the impact speed of Harley-Davidson motorcycles. The most accurate model was the Modified Eubanks set of equations introduced in 2009, producing errors with an average of 0.4 mph and a standard deviation (SD) of 4.8 mph. An updated set of Eubanks-style equations were developed adding data published since 2009, and advancing from two equations (pillars/axles and doors/fenders) to four equations (axles, pillars/bumpers, doors, and fenders). When applied to the subject tests, the newly developed set of equations produced an average error of 3.5 mph (SD = 4.3 mph). With respect to all available data (N = 99), the equations produced an average error of 0.1 mph and a standard deviation of 5.8 mph. The errors were also analyzed for each of the four equations developed here, and confidence intervals offered. This research, which represents the first detailed analysis of Harley-Davidson motorcycles’ collision response, indicates they behave in a manner similar to previously tested motorcycles. Further, the equations developed and presented here give accident investigators a refined method for estimating the impact speed of an upright motorcycle, Harley-Davidson or otherwise, having struck an automobile with its front tire.
Peck, Louis, Manning, Joseph, Bartlett, Wade, Dickerson, Charles, Deyerl, Eric
Supervisory Model Predictive Control of a Powertrain with a Continuously Variable Transmission2018-01-08604/3/2018
This paper describes the design of a supervisory multivariable constrained Model Predictive Control (MPC) system for driver requested axle torque tracking with real-time fuel economy optimization that is scheduled for production by General Motors starting in 2018. The control system has been conceived and co-developed by General Motors and ODYS. The control approach consists of a set of linear MPC controllers scheduled in real-time based on powertrain operating conditions. For each MPC controller, a linear model is obtained by system identification with vehicle and dynamometer data. The supervisory MPC coordinates in real time desired Continuously Variable Transmission (CVT) ratio and desired engine torque to satisfy the system requirements, based on estimates of axle torque and engine fuel rate, by solving a constrained optimization problem at each sampling step. Each linear MPC controller is equipped with a Kalman filter to reconstruct the system state from available measurements. Compared to more classical controls, the presented MPC approach achieves better coordination of powertrain actuators to satisfy system requirements, while maintaining robustness with respect to measurement noise, ambient conditions, and part-to-part variations. Moreover, the systematic, model-based framework developed for production enables a potential adaptation of the design to different powertrain architectures.
Bemporad, Alberto, Bernardini, Daniele, Livshiz, Michael, Pattipati, Bharath
Development of Axial Force Testing System for Wheel Bearing2017-01-25229/17/2017
The actual installed conditions of 1st, 2nd and 3rd generation of wheel bearing were introduced. The theoretical factors of the axial fastening force for the axle (or CVJ bolts) and nuts were analyzed and the requirements for building up a precise axial force test system were given out. Four testing plans were discussed for the requirements. Based on the cases, the axial force test system was built up, and the axial force test was successfully carried out for the front wheel bearing of a car.
Wen, Chao, Zhang, Lu, Luo, Tong, Huang, Dejie, Liu, Yu
Estimation and Reduction of Lateral Deviation (Brake Pulling) of a Vehicle due to Difference in Left and Right Wheel Brake Force2017-01-25059/17/2017
This paper explains a method to estimate and reduce brake pulling of vehicles due to force difference between RH and LH brake during straight ahead braking. One of the cause of brake pulling during straight ahead braking is brake force difference between right and left brakes of front and rear axles. It is challenging to eliminate this unwanted pulling especially during panic braking in shorter wheelbase vehicles having high center of gravity (CG) and drum brake on all wheels. A mathematical model is developed to estimate amount of brake pulling from known parameters like brake force, tire properties, steering geometry, suspension hard points, vehicle CG, scrub radius, castor angle etc. Vehicle tests were conducted to measure amount of brake pulling and close correlation was observed between vehicle test results and derived model. Vehicle test results also revealed that brake force difference between LH and RH wheel can change considerably from start to end during a single braking event itself. In addition, brake force difference may vary significantly with change in brake temperature and pressure. Pulling while braking can also occur due to bump steer and brake steer because of suspension spring wind-off and backward movement of front axle. When pulling due of these factors is in the same direction as pulling due to brake force difference, extent of vehicle deviation increases considerably. This model also identifies the most sensitive parameters causing brake pulling and helps in their optimization. The test vehicle was updated to have optimized parameters and was re-tested. Re-test results show substantial reduction in pulling as predicted by the mathematical model.
Shridhare, Mahesh, Sonar, Santosh, Ranawat, Manish, Jindal, Ajit Kumar
Gear Whine Noise Investigation of a Bus Rear Axle - Todays Possibilities and Outlook2017-01-18206/5/2017
This paper presents a simulation environment and methodology for noise and vibration analyses of a driven rear axle in a bus application, with particular focus on medium to high frequency range (400 Hz to 3 kHz). The workflow demonstrates structure borne noise and sound radiation analyses. The fully flexible Multi-Body Dynamics (MBD) model - serving to cover the actual mechanical excitation mechanisms and the structural domain - includes geometrical contacts of hypoid gear in the central gear and planetary gear integrated at hubs, considering non-linear meshing stiffness. Contribution of aforementioned gear stages, as well as the propeller shaft universal joint at the pinion axle, on overall axle noise levels is investigated by means of sensitivity analysis. Based on the surface velocities computed at the vibrating axle-housing structure the Wave Based Technique (WBT) is employed to solve the airborne noise problem and predict the radiated sound. Actual capabilities and limitations of the applied hypoid gear contact model are identified by comparing simulated and measured housing surface acceleration as well as sound pressure levels. Finally, a superior hypoid gear contact model based on preceding Loaded Tooth Contact Analysis (LTCA) is suggested for future extension of the methodology.
Sopouch, Martin, Hozmec, Josip, Cadario, Alessandro
FWD Halfshaft Angle Optimization Using 12 Degree of Freedom Analytical Model2017-01-17706/5/2017
This paper describes the development of an analytical method to assess and optimize halfshaft joint angles to avoid excessive 3rd halfshaft order vibrations during wide-open-throttle (WOT) and light drive-away events. The objective was to develop a test-correlated analytical model to assess and optimize driveline working angles during the virtual design phase of a vehicle program when packaging tradeoffs are decided. A twelve degree-of-freedom (12DOF) system model was constructed that comprehends halfshaft dynamic angle change, axle torque, powertrain (P/T) mount rate progression and axial forces generated by tripot type constant velocity (CV) joints. Note: “tripot” and “tripod” are alternate nomenclatures for the same type of joint. Simple lumped parameter models have historically been used for P/T mount optimization; however, this paper describes a method for using a lumped parameter model to also optimize driveline working angles. The 12DOF model results enable evidence-based decisions during the virtual vehicle phase for driveline working angles, powertrain mount rate and locations relative to P/T center of gravity. Several challenges were encountered and addressed during the 12DOF model development and correlation process, including halfshaft dynamic angle determination, P/T lateral rigid body mode frequency determination and subjective rating prediction.
Hill, Wallace, Kinchen, Dennis, Gehringer, Mark A.
Effect of Component Flexibility on Axle System Dynamics2017-01-17726/5/2017
The prediction and control of gear vibration and noise has become very important in the design of a quiet, high-quality gearbox systems. The vibratory energy of the gear pair caused by transmission error excitation is transmitted structurally through shaft-bearing-housing assembly and radiates off from exterior housing surface. Most of the previous studies ignore the contribution of components flexibility to the transmission error (TE) and system dynamic responses. In this study, a system level model of axle system with hypoid gear pair is developed, aiming at investigating the effect of the elasticity of the shafts, bearings and housing on TE as well as the contribution of flexible bearings on the dynamic responses. The load distribution results and gear transmission errors are calculated and compared between different assumptions on the boundary conditions. The modal characteristics and dynamic responses by assuming simply-support bearing and flexible bearing have also been compared. The results reveal that the system responses are sensitive to the system elasticity and shaft-bearing flexibility. The proposed approach yields a more in-depth understanding to the gear vibration propagation for use in the design of quiet driveline systems.
Wang, Yawen, Li, Xuan, Qiao, Guan, Lim, Teik
The Aerodynamic Development of the New Audi Q52017-01-15223/28/2017
The aerodynamic development of the new Audi Q5 (released in 2017) is described. In the course of the optimization process a number of different tools has been applied depending on the chronological progress in the project. During the early design phase, wind tunnel experiments at 1:4 scale were performed accompanied by transient DES and stationary adjoint simulations. At this stage the model contained a detailed underbody but no detailed engine bay for underhood flow. Later, a full scale Q5 model was built up for the aerodynamic optimization in the 1:1 wind tunnel at Audi AG. The model featured a detailed underbody and engine bay including original parts for radiators, engine, axles and brakes from similar vehicles. Also the 1:1 experiments were accompanied by transient DES and stationary adjoint simulations in order to predict optimization potential and to better understand the governing flow. The strong coupling of experimental and numerical tools enabled a best-in-class drag coefficient to be achieved not only for a single optimized vehicle setup but for the majority of four cylinder diesel and gasoline engines in base configuration even in SUV ground clearance (as required for LDT). This is not only true if the vehicle is equipped with the aerodynamically optimized “aero wheel” but also a number of optional rim designs allow comparably low drag values. In order to reach such low aerodynamic drag values, a variety of design and technical measures were necessary. A description of their definition and function is subject of the present paper.
Blacha, Thomas, Islam, Moni
Kinematic Analysis of Tractor-Semitrailer with Split Fifth Wheel Coupling During Low Speed Turning Maneuvers2017-01-15543/28/2017
Over the years, commercial vehicles, especially tractor-semitrailer combinations have become larger and longer. With the increasing demand for their accessibility in remote locations, these vehicles face the problem of off-tracking, which is the ensuing difference in path radii between the front and rear axles of a vehicle as it maneuvers a turn. Apart from steering the rear axle of the semitrailer, one of the feasible ways of mitigating off-tracking is to shift the fifth wheel coupling rearwards. However, this is limited by the distribution of the semitrailer’s load between the two axles of the tractor; any rearward shift of the fifth wheel coupling results in the reduction of the total static load on the tractor’s front axle and hence available traction. This may in turn lead to directional instability of the vehicle. In the present work, a new model of the fifth wheel coupling is proposed which the authors call Split fifth wheel coupling (SFWC). Here, unlike the Conventional fifth wheel coupling (CFWC), the point of load transfer from the semitrailer to the tractor and the point of articulation are separated by a certain distance. A comparative study of the kinematic analysis for the vehicle combination with CFWC and SFWC is discussed in this paper. It is observed that the latter noticeably reduces off-tracking when compared to the vehicle with CFWC for a tractor-semitrailer combination of similar dimensions.
Jogi, Ajith, Chandramohan, Sujatha
A Low Cost Rolling Road for Tire Measurements in a Small Eiffel Wind Tunnel2017-01-15043/28/2017
Wind tunnel aerodynamic testing involving rolling road tire conditions can be expensive and complex to set up. Low cost rolling road testing can be implemented in a 0.3m2 Eiffel wind tunnel by modifying a horizontal belt sander to function as a moving road. This sander is equipped with steel supports to hold a steel plate against the bottom of the wind tunnel to stabilize the entire test section. These supports are bolted directly into the sander frame to ensure minimal vibrational losses or errors during testing. The wind tunnel design at the beginning of the project was encased in a wooden box which was removed to allow easier access to the test section for installation of the rolling road assembly. The tunnel was also modified to allow observers to view the testing process from various angles. These wind tunnel modifications include replacing the wooden panels with clear Lexan plastic sheets, adding dampening material into the test section connections, and making an easily interchangeable test piece in the side of the tunnel for quick experimental changes. The tire axle assembly, designed to hold the tire as it freely rotates on the sander belt, records the various forces acting on the wheel. The wind tunnel stinger uses a steel airfoil cross section with a ball joint pivot to transfer the forces and moments to load cells aligned with the desired force directions. The load cells are calibrated and forces measured using a LabVIEW computer system and force comparisons are made with a static tire under the same wind conditions to help determine differences between static tire testing and dynamic tire testing.
Tkacik, Peter, Carpenter, Zachary, Gholston, Aaron, Cobb, Benjamin James, Kennedy, Sam, Blankenship, Ethan, Uddin, Mesbah, Krishna Nukala, Surya Phani
Chicago fire: Dodge puts 375-hp Hemi V8 in Durango SRT17AUTP03_103/1/2017
“Performance” SUVs are not a new concept, but FCA's Dodge brand opens a new niche-within-a-niche with the unveiling of the 2018 Durango SRT at the 2017 Chicago auto show, calling it “the fastest SUV in its class.” Dodge officials didn't directly say just who's asking for a grocery-getter SUV with 475 hp (354 kW) and 470 lb·ft (637 N·m) from a 6.4-L (or, more historically relevant, 392-in3) V8 that enables cutting a 12.9-s quarter mile time, but the Durango SRT will be in showrooms for that buyer starting in the fourth quarter. Some of the work of adapting the 6.4-L Hemi for the Durango already was done: it is the same iron-block, pushrod V8 with a 10.9:1 compression ratio that appears in the Jeep Grand Cherokee SRT, which shares its architecture with the Durango.
Visnic, Bill
Study of Different Twist-Beam Axle Configurations in Elastokinematics and Handling Behavior of a Vehicle2016-36-018410/25/2016
The twist-beam suspension is widely used in vehicles due to the simplicity of its construction, less occupied space and its low manufacturing cost in comparison with multi-link suspension. The difficulties related to the design of a twist-beam axle concern the large number of possible configurations for twist-beam profile and the stiffness adjustment of axle beam and suspension arms. However, design process can be done with the aid of multibody dynamics simulations, by testing several configurations in a virtual way. In this work, a simplified twist-beam suspension model is studied, and the influence of variation of its parameters is analyzed in its elastokinematics behavior and in handling performance of a vehicle.
Morales, Eduardo Domingo
Design and Research of Micro EV Driven by In-Wheel Motors on Rear Axle2016-01-19509/18/2016
As is known to all, the structure of the chassis has been greatly simplified as the application of in-wheel motor in electric vehicle (EV) and distributed control is allowed. The micro EV can alleviate traffic jams, reduce the demand for motor and battery capacity due to its small size and light weight and accordingly solve the problem that in-wheel motor is limited by inner space of the wheel hub. As a result, this type of micro EV is easier to be recognized by the market. In the micro EV above, two seats are side by side and the battery is placed in the middle of the chassis. Besides, in-wheel motors are mounted on the rear axle and only front axle retains traditional hydraulic braking system. Based on this driving/braking system, distribution of braking torque, system reliability and braking intensity is analyzed in this paper. In order to coordinate with traditional hydraulic ABS control to ensure the braking stability of the vehicle, model following control (MFC) is adopted to fully utilize the fast and accurate torque response of motor for slip prevention and control effect influenced by characteristics of motor is analyzed. In conclusion, only simple and minor changes have been made to the braking system of traditional vehicle which makes the micro EV cost less and easier to popularize.
Zhuo, Guirong, Zhang, Subin, Xiong, Kun
A Robust Stability Control System for a Hybrid Electric Vehicle Equipped with Electric Rear Axle Drive2016-01-16494/5/2016
Optimizing/maximizing regen braking in a hybrid electric vehicle (HEV) is one of the key features for increasing fuel economy. However, it is known [1] that maximizing regen braking by braking the rear axle on a low friction surface results in compromising vehicle stability even in a vehicle which is equipped with an ESP (Enhanced Stability Program). In this paper, we develop a strategy to maximize regen braking without compromising vehicle stability. A yaw rate stability control system is designed for a hybrid electric vehicle with electric rear axle drive (ERAD) and a “hang on” center coupling device which can couple the front and rear axles for AWD capabilities. Nonlinear models of the ERAD drivetrain and vehicle are presented using bond graphs while a high fidelity model of the center coupling device is used for simulation. A robust yaw rate stability controller, utilizing Youla parameterization, is proposed which uses the center coupling device to distribute regen braking torque from the rear axle to the front axle while using the maximum amount of regen braking possible to help improve fuel efficiency. It is shown through simulation studies that the proposed controller stabilizes a vehicle cornering whilst braking on a low friction surface while using the maximum amount of regen braking possible. The controller is also shown to be robust to time delays in the system. The resulting control system helps improve overall fuel efficiency during all braking maneuvers by maximizing the amount of regen braking available from the system at any given time.
Velazquez Alcantar, Jose, Assadian, Farhad
Development of Electric Drive System for New Model Super Sports Hybrid Vehicle2016-01-16854/5/2016
A three-motor hybrid system suitable for a super sports car was developed. This system features high power, light weight and high response, and has high cooling performance for high-load operation such as circuit driving. The power plant drives the rear wheels using the combination of a midship-mounted V6 twin-turbo engine, the direct drive motor of a hybrid system mounted directly on the engine, and a 9-speed dual-clutch transmission (DCT). The front wheels are driven by a twin-motor unit (TMU), and the size and weight of the Intelligent Power Unit (IPU) that supplies electric power to the TMU has been reduced to enable mounting behind the seats inside the cabin. In addition, the IPU uses air-conditioner cooperative cooling to enhance the cooling performance. As a result, assist is performed even during high-load operation. By utilizing this system, driving force can be distributed properly to the wheels on both sides of front and the axles of back and front to maximize acceleration and cornering performance during all situations. As a result, direct vehicle behavior according to driver's intention is realized. Electric drive (E-Drive) system has achieved following: High-response powertrain and high acceleration performance are achieved by E-Drive system Improvement of cornering performance by drive force distribution using three motors High power output continuation for circuit driving by high cooling performance
Tamura, Sayaka, Yoshinari, Tsutomu
Study on Power Ratio Between the Front Motor and Rear Motor of Distributed Drive Electric Vehicle Based on Energy Efficiency Optimization2016-01-11544/5/2016
For distributed drive electric vehicles (DDEVs), the influence of the power ratio between the front and rear motors on the energy efficiency characteristics is investigated. The power-train systems of the DDEVs in this study are divided into two different power-train configurations. The first is with its front axle driven by wheel-side motors and the rear axle driven by in-wheel motors, and the second is with both the front and rear axles driven by in-wheel motors. The energy consumption simulation and analysis platform of the DDEV is built with Matlab/Simulink. The parameters of the key components are determined by the experiments to ensure the validity of the data used in simulation. At the same time, the vehicle’s average energy efficiency coefficient is defined to describe the energy efficiency characteristics of the power-train strictly. Besides, the control strategies for driving and braking of the DDEV based on energy efficiency optimization are presented. Then, based on the existing energy efficiency MAPs of the power components including motor, inverter and reducer, the methods which calculate the energy efficiency MAPs of the power components with other sizes by calculating power losses related to the parameters and sizes are proposed. Thus, the energy efficiency MAPs of the power-train with different power ratios between the front and rear motors are acquired. Several simulations with different typical driving cycles are implemented to compare the energy efficiency characteristics of different power-train configurations. As a result, based on the energy efficiency optimization, we propose the best power ratio between the front and rear motors, which is about 1:2.5 for the power-train using front wheel-side motors and rear in-wheel motors, while about 2:1 for another configuration. Our works can provide recommendations for allocation of front motor power and rear motor power for DDEVs.
Shen, Peihong, Sun, Zechang, Zeng, Yingjie, Wang, Xinjian, Dai, Haifeng
Development of Hybrid Powertrain System for Small Vehicles2016-01-11714/5/2016
Electrification of the powertrain to improve vehicle fuel economy is a key technology to achieve strict fuel economy legislation. However, only limited numbers of small class vehicles such as a B segment adopt electric powertrain. This is presumed that cost effectiveness for fuel economy is small and mounting space for additional powertrain is limited. In this paper, the optimum solution of a strong hybrid system suitable for the small vehicles was studied. First, from the viewpoint of maximization of energy efficiency, we compared contributions of engine efficiency and transmission efficiency during mode cycle driving and selected automated manual transmission as a suitable transmission for small vehicles. In comparing the hybrid system function, we determined a motor generator connecting shaft and a necessary motor generator output power for attaining both fuel economy and drivability. Further, motor generator and gear arrangement were designed to realize the shift change without torque interruption and shorter axle length than conventional manual transmission. The functional prototype of an automated manual transmission hybrid system and a test vehicle were built. Furthermore, we introduce vehicle evaluation result of the shift change sequence without torque interruption and the possibility of flexible drivability.
Hirose, Shota, Okawa, Akemi, Ishida, Kenji, Misu, Takahiro, Tojo, Takeshi
Through-the-Road Parallel Hybrid with In-Wheel Motors2016-01-11604/5/2016
Present automobile development is keenly focused on measures to reduce the CO2 output of vehicles. Plug-in hybrid electric vehicles (PHEVs) enable grid electricity, which is clean in tail-pipe emissions terms, to be utilised whilst the on-board electrical storage has sufficient charge. MAHLE Powertrain and Protean have jointly developed a plug-in hybrid demonstrator vehicle based on a C-segment passenger car. The vehicle features Protean’s compact direct drive in-wheel motors with integrated inverters on the rear axle and retains the standard gasoline engine, and manual transmission, on the front axle. To support this one-off prototype, a flexible vehicle control unit has been developed, which is easily re-configurable and adaptable to any hybrid vehicle architecture. The unit operates using software developed by MAHLE Powertrain to achieve a fully configurable vehicle control unit (VCU), intended to provide a rapid and cost effective platform for the development of demonstrator and niche volume vehicle fleets. This paper describes some of the challenges, and solutions, associated with the vehicle conversion, including key vehicle integration topics, such as the CAN interface, vehicle control strategy, and the cooling system.
Hall, Jonathan, Bassett, Michael, Borman, Stephen, Lucas, Tom, Whitehead, Andrew
Suspension and Mass Parameter Measurements of Wheeled Vehicles2015-01-27519/29/2015
The United States Army Tank Automotive Research, Development and Engineering Center (TARDEC) built systems to measure the suspension parameters, center of gravity, and moments of inertia of wheeled vehicles. This is part of an ongoing effort to model and predict vehicle dynamic behavior. The new machines, the Suspension Parameter Identification and Evaluation Rig (SPIdER) and the Vehicle Inertia Parameter Evaluation Rig (VIPER), have sufficient capacity to cover most heavy, wheeled vehicles. The SPIdER operates by holding the vehicle sprung mass nominally fixed while hydraulic cylinders move an “axle frame” in bounce or roll under each axle being tested. Up to two axles may be tested at once. Vertical forces at the tires, displacements of the wheel centers in three dimensions, and steer and camber angles are measured. Contact patch can move in lateral, longitudinal and steer motions of the suspension and the small deflections of the vehicle sprung mass resulting from the contact patch forces are measured. For steer axles the steering ratio, Ackerman steer characteristics, and kingpin orientation are measured. The VIPER measures center of gravity and vehicle principle moments of inertia. The roll-yaw cross product and the center of gravity height is measured by holding the vehicle body nominally fixed to a large platform while rotating the platform about the pitch, roll, and yaw axes.
Baseski, Igor, Norman, Kenneth, Ryan, David, Stahara, Stefanie
Directional Dynamics of Steering the Third Axle2015-01-27479/29/2015
With the expectation that means of redundant steering will be necessary for highly autonomous vehicles, different methods of providing redundant steering can be considered. One potential for redundancy is to steer the rear axle for directional control of the vehicle in the event of a failure in the primary steered front axle. This paper will characterize the dynamics of directional control of a three-axle vehicle when steered at the rear, and compare it to a conventionally steered three-axle vehicle. Several compensators are suggested that allow similar vehicle dynamic behavior when steering the rear axle as a driver would expect when steering the front, giving hope that a steerable rear axle can provide acceptable redundancy for a failed primary steering system on the front axle.
Williams, Daniel E., Nhila, Amine
Tuning Axle Whine Characteristics with Emphasis on Gear Dynamics and Psychoacoustics2015-01-21816/15/2015
A combined lumped parameter, finite element (FE) and boundary element (BE) model is developed to predict the whine noise from rear axle. The hypoid geared rotor system, including the gear pair, shafts, bearings, engine and load, is represented by a lumped parameter model, in which the dynamic coupling between the engaging gear pair is represented by a gear mesh model condensed from the loaded tooth contact analysis results. The lumped parameter model gives the dynamic bearing forces, and the noise radiated by the gearbox housing vibration due to the dynamic bearing force excitations is calculated using a coupled FE-BE approach. Based on the predicted noise, a new procedure is proposed to tune basic rear axle design parameters for better sound quality purpose. To illustrate the salient features of the proposed method, the whine noise from an example rear axle is predicted and tuned. The noise prediction results indicate that the spectral components of the calculated noise are mainly caused by the gear out of phase modes and the housing structure modes. The simulation results also indicate that the loudness and sharpness of the noise radiated by the rear axle can be tuned and suppressed as gear rotor system dynamic parameters are properly modified.
Guo, Dong, Wang, Yawen, Lim, Teik, Yi, Peng
A Multibody Dynamics Approach to Leaf Spring Simulation for Upfront Analyses2015-01-22286/15/2015
Drivelines used in modern pickup trucks commonly employ universal joints. This type of joint is responsible for second driveshaft order vibrations in the vehicle. Large displacements of the joint connecting the driveline and the rear axle have a detrimental effect on vehicle NVH. As leaf springs are critical energy absorbing elements that connect to the powertrain, they are used to restrain large axle windup angles. One of the most common types of leaf springs in use today is the multi-stage parabolic leaf spring. A simple SAE 3-link approximation is adequate for preliminary studies but it has been found to be inadequate to study axle windup. A vast body of literature exists on modeling leaf springs using nonlinear FEA and multibody simulations. However, these methods require significant amount of component level detail and measured data. As such, these techniques are not applicable for quick sensitivity studies at design conception stage. This paper bridges this gap in the literature by developing a spring model at the conceptual phase using the multibody dynamics (MBD) tool Adams based on a minimal parameter set to define leaf geometry and profile. Linear Timoshenko beam theory is employed to model the leaves thus accounting for the beam cross-section rotation which facilitates simulation of bending and shear effects. This is essential for simulating spring seat angle changes during acceleration and braking under different vertical loads. A mono leaf spring case study is presented to demonstrate the modeling capability along with a sensitivity study to provide insights on factors that affect axle windup. The effect of drive torque and longitudinal load on the windup behavior of both symmetric and asymmetric springs is demonstrated. Two-stage symmetric and asymmetric spring models are validated against test data for windup. This methodology will help develop spring simulations quickly during the design conception phase and thereby provide valuable information regarding the response of integrated vehicle systems. This in turn will help drive the design from an early stage thereby preventing expensive and time-consuming design changes later in the product development phase.
Addepalli, Kalyan Chakravarthy, Remisoski, Natalie, Sleath, Anthony, Liu, Shyiping
Dynamic Decoupling of Driveline Dynamics from NVH Driveline Dynamometer: an Industry Sponsored Senior Design Project2015-01-23476/15/2015
The American Axle & Manufacturing Inc. driveline dynamometer provides immense value for experimental validation of product NVH performances. It has been intensively used to evaluate product design robustness in terms of build variations, mileage accumulation, and temperature sensitivity. The current driveline dynamometer input motor system has multiple torsional modes which create strong coupling with test part gear mesh dynamics. Mechanical Engineering seniors at Lawrence Technological University designed, fabricated, and validated a mechanism to decouple the driveline dynamics from the driveline dynamometer dynamics. The student-designed decoupler mechanism is presented with experimental validation of effectiveness in decoupling driveline dynamometer dynamics from the driveline under test.
Mynderse, James A., Sandstrom, Alexander, Sun, Zhaohui
NVH Development of Aluminum Axles2015-01-21886/15/2015
This paper discusses approaches to properly design aluminum axles for optimized NVH characteristics. By effectively using well established and validated FEA and other CAE tools, key factors that are particularly associated with aluminum axles are analyzed and discussed. These key factors include carrier geometry optimization, bearing optimization, gear design and development, and driveline system dynamics design and integration. Examples are provided to illustrate the level of contribution from each main factor as well as their design space and limitations. Results show that an aluminum axle can be properly engineered to achieve robust NVH performances in terms of operating temperature and axle loads.
Sun, Zhaohui, Steyer, Glen, Chung, Chih Hung, Kopp, Gregory
Active Control of Structure-Borne Road Noise Based on the Separation of Front and Rear Structural Road Noise Related Dynamics2015-01-22226/15/2015
Axle forces from tire-road interaction can excite different structural resonances of the vehicle hence a high number of sensors is required for observing and separating all the vibrations dynamics that are coherent with the cabin noise. Feed-forward road noise control strategies adopted so far rely mainly on capturing these dynamics and thus the number of sensors constitutes one major limitation of this approach. Therefore there is a necessity for reducing the number of sensors without degrading the performance of an ANC system. In the past coherence function analysis has been found to be a useful tool for optimizing the sensor location. In this case coherence function mapping was performed between an array of vibration sensors and the headrest microphones in order to identify the locations on the structure that are highly correlated with road noise bands in the compartment. A vehicle with an advanced suspension system was used for applying the method and defining some locations as reference signals for feed-forward active road noise control. Three different real-time control experiments were performed with structure-borne road noise simulated by applying broad band random forces to tires through shaker transducers. A single reference feed-forward adaptive controller evaluated the signals from each sensor location with simulated road noise excitation applied to: front wheels only, rear wheels only and whole vehicle. This way it is demonstrated that the control can be focused at specific road noise bands with a low number of sensors.
Zafeiropoulos, Nikos, Ballatore, Marco, Moorhouse, Andy, Mackay, Andy
Investigation and Optimization of Front Suspension and Steering Geometrical Compatibility2015-01-04924/14/2015
The need to develop products faster and to have designs which are first time right have put enormous pressure on the product development timelines, thus making computer aided optimization one of the most important tool in achieving these targets. In this paper, a design of experiments (DOE) study is used, to gain an insight as to, how changes to different parameters of front suspension and steering of a passenger bus affect its kinematic properties and thus to obtain an optimized design in terms of handling parameters such as bump steer, percent ackermann error and lock to lock rotation angle of steering wheel. The conventional hit and trial method is time consuming and monotonous and still is an approximate method, whereas in design of experiments (DOE), a model is repeatedly run through simulations in a single setup, for various combinations of parameter settings. Effects of the design variables of the model are then studied, which provides an insight to help design an optimized model. A subsystem level rigid body MSC ADAMS/View model is used which has a SAE 3 link leaf spring on front axle. The hard point locations of the steering linkages were varied and a design of experiments (DOE) study conducted using MSC ADAMS Insight, thus identifying the critical variables. These critical variables were then optimized using MSC ADAMS/ View tool to achieve the desired targets. The results of the optimization study are verified using objective measurement on a static vehicle and were found to be in good coherence with the model results.
Paliwal, Gaurav, Sukumar, Naveen, Gupta, Umashanker, Dubey, Ashutosh, Chopra, Nitin
Research and Verification on Ideal Stiffness Characteristic Curve of Suspension Coil Springs2015-01-13284/14/2015
Taking a domestic brand car as example, this paper is about how to find out a three-point nonlinear stiffness characteristic curve which can meet the requirements of variable stiffness and three-load condition. The new coil spring gives the passive suspension a lot of improvements in riding and safety, changing the nonlinear stiffness characteristic from weak to strong. This paper summarizes the optimization design method for the rear suspension coil spring, which includes the fitting of ideal stiffness characteristic curve, quantitative method for figuring out how the change of vehicle load influences the load on rear suspension axle, the design method of variable stiffness coil spring which corresponds to the change of vehicle load. A new kind of modified ideal point solution for building the objective function was also put forward. Using the kits Fminimax, Fmincon in Matlab as optimization tools, finally verify the validity of optimization result through the four post testing module in ADAMS/Car.
Gao, Da-Wei, Huang, Xing-Xing, Xu, Jun, Zheng, Song-Lin
Tyre Load Analysis of Hydro-Pneumatic Interconnected Suspension with Zero Warp Suspension Stiffness2015-01-06304/14/2015
The purpose of this paper is to present a concept of Hydro-Pneumatic Interconnected Suspension (HPIS) and investigate the unique property of the zero warp suspension stiffness. Due to the decoupling of warp mode from other modes, the road holding ability of the vehicle is maximized meanwhile the roll stability and ride comfort can be tuned independently and optimally without compromise. Ride comfort can be improved with reduced bounce stiffness and the progressive air spring rate can reduce the requirement of suspension deflection space. The roll stability can also be improved by increased roll stiffness. Vehicle suspension system modelling and modal analysis are carried out and compared with conventional suspension. The frequency response of tyres' dynamic load reveals that the proposed zero-warp-stiffness suspension enables the free articulation of front and rear axles at low frequency. The wheel load transfer is significantly reduced when travelling on uneven off-road surface at low speed, hence the handling/traction performance are greatly improved and twisting load on vehicle body/frame can be reduced.
Xu, Guangzhong, Zhang, Nong, Roser, Holger, Ruan, Jiageng
Improved Lane-keeping with Rear Axle Steer2015-01-15844/14/2015
The classic two-degree-of-freedom yaw-plane or “bicycle” vehicle model is augmented with two additional states to describe lane-keeping behavior, and further augmented with an additional control input to steer the rear axle. A simple driver model is hypothesized where the driver closes a loop on a projected lateral lane position. A rear axle steer control law is found to be a function of front axle steering input and vehicle speed that exhibits high speed stability and improved low speed maneuverability. The theoretically derived control law bears similarity to practical embodiments allowing a deeper understanding of the functional value of steering a rear axle.
Williams, Daniel E.
Comparative Analysis on a Rectilinear Independent Suspension with Traditional Ones2015-01-06324/14/2015
Suspension plays an essential role in vehicle's handling stability and riding comfort. This paper discusses a novel suspension that has the capacity to trace a straight line in theory. Therefore it is called rectilinear suspension. So the alignment parameters are invariable during jounce and rebound if the elasticity of suspension components is ignored. According to the structure characteristics of the rectilinear suspension, it is suitable to mount on the rear axle. To evaluate its performance, the dynamics model is established through ADAMS. Moreover, a comparison of the rectilinear suspension with the twin-trapezoidal link suspension is carried out. Further, the K&C test results show that the alignment parameters of the rectilinear suspension are almost invariable compared with MacPherson suspension.
Liu, Xiang, Zhang, Jie, Zhao, Jingshan
Automotive Engineering: February 3, 201515AUTP022/3/2015
Getting a grip on AWD efficiency The safety and performance benefits of all-wheel drive are undeniable, but so are the penalties of added weight, friction losses, and complexity. Clever axle disconnects and E-axles are driving future AWD developments. E pluribus unum Inputs from many sensors are being combined to give safety systems a true vision of vehicle surroundings, with the resulting sensor fusion becoming a mainstay of autonomous vehicle electronics. Lightweighting poses repair challenges Mass-produced aluminum bodies and mixed-material structures present challenges for assembly and repair, as automakers increasingly pursue these lightweight strategies. Setting the standard Meggitt CTO Emeritus begins term at helm of SAE International, seeks to encourage cross-sector relations, elevate image of SAE as aerospace industry leader.
Delivering Axle Efficiency and Fuel Economy Through Optimised Fluid Design2014-01-279910/13/2014
The fuel economy of vehicles is today in everyone's focus. Governments, original equipment manufacturers, and consumers alike are all demanding improvements. Historically, reducing oil viscosity has resulted in improved fuel economy; however, lower viscosities can lead to reduced or “weakened” lubricant films, which may fail to hold up under higher temperatures and heavy loading associated with axle operations. The fluid development challenge is to bridge the gap between fuel economy and operating temperature control. Achieving both fuel economy and durability are not always compatible objectives. The real challenge is to build in the high torque protection historically associated with higher viscosity grades, like SAE 75W-90, while delivering the axle efficiency of lighter grades such as an SAE 75W-85 grade. In previous work, it has been shown that critical factors for achieving the proper efficiency-durability balance include viscosity, traction, fluid film thickness and additive chemistry. [1,2,3,4,5] Axle oils are subjected to different modes of energy dissipation: losses related to loading and losses that are independent of loading i.e., churning or spin losses. In designing versatile axle lubricants, an understanding of fluid rheological properties under both high and low loading is important. High loading is indicative of certain operations such as taxis, while lower loading is consistent with normal city-highway driving. The term durability has many manifestations however here it is used principally to describe a fluid's effect on operating temperature under high speed conditions (as in motorway and autobahn situations). An important consequence of poor or insufficient fluid durability is bearing failure; therefore, bearing life testing has been included in this investigation. The growing need for improved fuel economy is also a global issue due to the relationship between reduced fuel consumption and reduced CO2 emissions. The challenge for vehicle manufacturers is to match the proper fluid with the application to provide the required durability protection while maximizing fuel efficiency. This paper will describe the use of controlled laboratory testing methods for the development of axle fluids that maximize both the fuel efficiency and durability performance across the spectrum of the new viscosity classifications. The relationship of viscosity and fluid formulation choices will be examined with respect to inherent fluid properties, as well as the impact of these fluid properties on axle efficiency and temperature performance characteristics.
Evans, Simon David
Oxidation of Axle Lubricants - Laboratory Studies and a Model to Predict Service Life2014-01-280110/13/2014
The continuing push for improved fuel economy, reduced carbon emissions, and lower operating costs has resulted in higher operating temperatures for axle lubricants in passenger cars and commercial vehicles. These higher operating temperatures, in turn, have placed more severe demands on the thermal & oxidative performance of axle lubricants. A number of industry-standard, laboratory methods exist to evaluate this key performance parameter. This paper discusses the use of laboratory methods to evaluate oil service life. We examine the behavior of five commercially available axle lubricants in the CEC L-48 oxidation test (Apparatus A). The oils were chosen so that different additives and base oils could be compared. We evaluated both the effect of time and temperature on the oxidation behavior. In agreement with previous studies, we found that infrared (IR) spectroscopy provides a convenient and meaningful way to track the extent of oxidative degradation. We define the “breaking point” of an oil as the value of IR Peak Area Increase (PAI) at which deposits first appear. We propose a simple model for estimating the total endurance life of an axle lubricant by dividing the breaking point by the rate of oxidation as measured by PAI.
Zakarian, Jack, Webber, Clive
Recent Experimental and Simulation Efforts to Mitigate Wobble and Shimmy in Commercial Line Haul Vehicles2014-01-23149/30/2014
Wobble and shimmy vibrations are commonly observed in commercial highway vehicles with solid-beam front axles. These vibrations are typically self-excited and manifest themselves as sustained oscillations about the kingpin and axle tramp. A study was initiated to investigate and quantify wobble and shimmy behaviors, with a primary focus on wobble. A cross functional team including test and simulation engineers evaluated a vehicle exhibiting these behaviors. The team developed an ADAMS model to reproduce the behaviors and developed a DOE to quantify the impact of variables and combinations of variables. The evaluation demonstrated that dynamic imbalance in the rotating masses is a primary source of excitation. Wheel run-out, caster angle, tire brand, tire wear and tire inflation are also significant sources. Future studies will use these findings to mitigate the concern.
Stuart, John, Cassara, Stefano, Chan, Brendan, Augustyniak, Nicholas
Comparison of Fuel Efficiency and Traction Performances of 6 × 4 and 6 × 2 Class 8 Tractors2014-01-23589/30/2014
The objective of this project was to compare the fuel consumption and traction performances of 6 × 2 and 6 × 4 Class 8 tractors. Two approaches have been considered: evaluation of 6 × 2 tractors, modified from 6 × 4 tractors, and evaluation of OEM 6 × 2 tractors. Compared to the 6 × 4 tractors, which are equipped with a rear tandem with both drive axles, the 6 × 2 tractors have a rear tandem axle with one drive axle, and one non-drive axle, also called dead axle. The 6 × 2 tractor configurations are available from the majority of Class 8 tractor manufacturers. The SAE Fuel Consumption Test Procedures Type II (J1321) and Type III (J1526) were used for fuel consumption track test evaluations. Traction performances were assessed using pull sled tests to compare pulling distance, maximum speed, and acceleration when pulling the same set sled on similar surface. Fuel consumption tests showed that 6 × 2 tractors consume up to 3.5% less than the similar 6 × 4 tractors, whilst pull sled tests showed shorter distance, lower maximum speed, and lower acceleration for the 6 × 2 tractors, when compared to similar 6 × 4 tractors. These differences are not critical or even not observable in normal operating conditions of on-highway transport but in specific conditions characteristic of particular northern operations, these differences could impact the performance of the tractor. However, systems are available for transferring the load from the dead axle to the drive axle in special conditions, for increasing the traction. With 6 × 2 axles, traction tires can be installed only on the drive axle, while the dead axle can be equipped with more fuel-efficient tires, which can bring more fuel savings and tire cost savings. Another advantage is the weight reduction: it was shown that the 6 × 2 tractors were lighter than the 6 × 4 tractors, and reducing a vehicle's tare weight can translate into an increase in payload, which would enhance freight transportation efficiency. At no additional cost, the 6 × 2 tractors replacing 6 × 4 Class 8 tractors could reduce annually the GHG emissions up to 1.93 tonnes per vehicle.
Surcel, Marius-Dorin, Provencher, Yves
Innovative Methodology for Durability Evaluation of Off Road Vehicle Rear Axle under Bi-Axial Load Condition using Single Linear Actuator2014-01-23069/30/2014
Rear axles are subjected to bending and torsion loads out of which Bending loads are predominant. In case of Off road vehicles Bi Axial- combination of Bending and torsion loads were predominant, because of axle construction and vehicle usage pattern. Defined test procedures are available for bending durability and torsional durability evaluation of axles. In this experiment, new test methodology was developed for Bi Axial durability evaluation of Off road vehicle rear axle with single servo hydraulic linear actuator. For creating Bi Axial load condition, we may need multiple actuators and complicated fixtures. Axle wheel end is constrained at an angle with suitable fixtures for creating the bending and torsional forces together in the axle. Servo hydraulic linear actuator with suitable loading arm is used for applying the test torque in the axle input flange. Vehicle parameters like Engine torque, wheel reaction, axle ratio and wheel static loaded radius (SLR) etc., used for arriving the test specification. Strain gauging (Rosette) and data acquisition techniques are used for ensuring the proper load transfer to the axle. Data acquired in Bending, torsion and Bi-Axial (bending cum torsion) load condition. It is evident from the strain data with the newly developed test methodology Bi axial load condition was simulated in the axle. Endurance test of axle assembly was carried out with the new test methodology for validating the test method and identifying the failure modes. The benefits of this exercise include: 1 Bi-Axial Torsion-Bending load condition created using a single actuator and with the help of simple fixtures. 2 Test methodology developed for Bi-Axial Torsion-Bending durability evaluation. 3 Strain Gauging and data acquisition techniques effectively used for test methodology comparison/Validation.
Balaji, Mathialagan, Bhatkar, Hemant, Ranjith Kumar, Jeya Kumar, Anbazhagan, Ananthan, Palkar, Pramod
A New Electric Powertrain for Light Trucks: Indoor Testing and Advanced Simulation2014-01-19774/1/2014
A new electric powertrain and axle for light/medium trucks is presented. The indoor testing and the simulation of the dynamic behavior are performed. The powertrain and axle has been produced by Streparava and tested at the Laboratory for the Safety of Transport of the Politecnico di Milano. The tests were aimed at defining the multi-physics perfomance of the powertrain and axle (efficiency, acceleration and braking, temperature and NVH). The whole system for indoor tests was composed by the powertrain and axle (electric motor, driveline, suspensions, wheels) and by the test rig (drums, driveline and electric motor). The (driving) axle was positioned on a couple of drums, and the drums provided the proper torques to the wheels to reproduce acceleration and braking. Additionally a cleat fixed on one drum excited the vibration of the suspensions and allowed assessing NVH performance. The simulations were based on a special co-simulation between 1D-AMESIM and VIRTUAL.LAB. The contact between the wheels and the drums of the test rig were simulated by means of VIRTUAL.LAB. The simulation of the whole system was performed quickly. The comparison between the simulations and the experiments is satisfactory. The indoor test facility allows the quick tuning of the powertrain and axle parameters to meet the technical specification related to a particular application.
Golimbioschi, Robert, Mastinu, Giampiero, Cordioli, Luca, Gobbi, Massimiliano, Tagliabue, Davide, Previati, Giorgio, Braga, Francesco
Control Analysis under Different Driving Conditions for Peugeot 3008 Hybrid 42014-01-18184/1/2014
This paper includes analysis results for the control strategy of the Peugeot 3008 Hybrid4, a diesel-electric hybrid vehicle, under different thermal conditions. The analysis was based on testing results obtained under the different thermal conditions in the Advanced Powertrain Research Facility (APRF) at Argonne National Laboratory (ANL). The objectives were to determine the principal concepts of the control strategy for the vehicle at a supervisory level, and to understand the overall system behavior based on the concepts. Control principles for complex systems are generally designed to maximize the performance, and it is a serious challenge to determine these principles without detailed information about the systems. By analyzing the test results obtained in various driving conditions with the Peugeot 3008 Hybrid4, we tried to figure out the supervisory control strategy. The engine of the vehicle is mostly turned on or off on the basis of the SOC, demand power, and vehicle speed according to the driver mode. If the engine is turned on, the front axle driven by the engine generally provides all propulsion power. Further, when the engine is on, the generator torque is controlled to satisfy the desired battery power, while the power is determined by SOC according to the driver mode. The control targets for the vehicle components are basically determined by these concepts. Several additional analysis results are provided such as creep torque control, engine on/off under different thermal conditions, and the energy consumption of the electrical accessories. The information provided in this paper should be helpful in understanding the system behavior of the Peugeot 3008 Hybrid4.
Kim, Namwook, Rask, Eric, Rousseau, Aymeric
Vehicle Modeling and Performance Evaluation Using Active Torque Distribution2014-01-01034/1/2014
The main aim of researchers, to prevent the spinning and drifting of vehicle, is to monitor the yaw stability control strategy. The yaw stability control system is incorporated with active torque distribution. A lot of work is done on torque distribution between right and left wheels using active differential to distribute torque to each drive wheel. Control algorithm based on different control strategies were used for torque distribution. In this study, active torque distribution strategy is incorporated via central transfer case between front and rear axle. A 4WD vehicle is used with 50-50 torque ratio amongst front and rear axle. The controlling parameter is the understeer and oversteer behavior of the vehicle. A combined slip model approach used by Burckhardt is used for a 10 DOF vehicle modeling using MATLAB. The simulated results will be compared against a multibody nonlinear simulation software i.e. CarSim. For implementation, J-turn test and Double Lane Change (DLC) were used.
Latif, Rizwan, Azim, Raja Amer, Baqai, Aamer Ahmed, Shafi, Imran
Sprung Mass Identification of Suspension in a Simplified Model2014-01-00514/1/2014
This paper describes a simplified model to identify sprung mass using golden section method, the model treats the unsprung mass vertical acceleration as input and the sprung mass vertical acceleration as output, which can avoid the nonlinear influence of trye. Unsprung mass can be also calculated by axle load and the identified sprung mass. This study carries out road test on the vehicle ride comfort and takes a scheme that the group of 20 km/h is used to identify sprung mass and the group of 80 km/h is used to verify the identification result. The similarity of the results from the simulation and experiments performed are, for the sprung mass, 98.59%. A conclusion can be drawn that the simple method to measure the sprung mass in the suspension systems in used vehicles, such as the vehicle shown here, is useful, simple and has sufficient precision.
Tang, Gang, Li, Jinning, Ding, Chao, Zhang, Yunqing
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