Browse Topic: Universal joints

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Steering Control Systems - Heavy TrucksJ2425_202111 (Current)11/9/2021
This SAE Recommended Practice describes a laboratory test procedure and requirements for evaluating the characteristics of heavy-truck steering control systems under simulated driver impact conditions, as well as driver entry/egress conditions. The test procedure employs a torso-shaped body block that is impacted against the steering wheel.
Truck Crashworthiness Committee
Universal Joint End Yoke Connection (Earwork)J2301_202101 (Current)1/7/2021
This document specified the main dimensions and tolerances which affect interchangeability between end yoke earwork for the most common North American-used universal joints. Dimensions and tolerances of the mating universal joints are left to the discretion of the universal joint manufacturers. The term “earwork” refers to the configuration and geometry defining end yoke connections directly provided for universal joint cross attachment of drivelines. Earwork for certain styles of universal joint connections and flange connections have for a long time been proprietary to certain manufacturers. Over years of usage, proprietary rights have expired and the industry, as a whole, has used these earworks as standard. In an effort to tabulate some of the long-established practices, the following SAE Recommended Practice has been compiled. Manufacturers do from time to time, as the need arises, change tolerances or fits to better enhance component performance. This document has been prepared as a reference, and is a snapshot of current technology. The half round (strap connection), full round (retainer plate type connection), and wing type connection are covered in this document. For an understanding of these end yoke styles, please refer to SAE J901. There are earwork forms that still are proprietary and are not covered by this document.
Drivetrain Standards Committee
An Interval Analysis and Optimization Method for Generated Axial Force of Automotive Drive Shaft Systems2020-01-09184/14/2020
To study the generated axial force (GAF) of the drive shaft system more accurately and effectively, this paper introduces the interval uncertainty into the research focusing on the GAF. Firstly, an interval uncertainty model for calculating the GAF is proposed based on the Chebyshev polynomials and an analytical model of the GAF. The input torque, the articulation angle, the rotation angle of the drive shaft system, the pitch circle radius (PCR) of the tripod joint and the friction coefficient are regarded as interval variables. Secondly, the upper and lower bounds of the proposed GAF model under interval uncertainty parameters are calculated quickly with the vertex method. Then the interval uncertainty optimization of the GAF under uncertainty parameters is performed. The upper bound of the response interval of the GAF is taken as the optimization object. Finally, the proposed model is verified by experiments, while the interval uncertainty analysis and optimization of the GAF are carried out through a numerical example.
Feng, Huayuan, Rakheja, Subhash
Research on Fractal Friction Model between Balls and Arc Raceways inside a Ball Joint2020-01-10934/14/2020
During the operation of the ball joint, its service life and transmission efficiency are affected by the internal friction. Taking the ball joint as the research object, based on fractal theory, the friction between the steel ball and the raceway inside the ball joint of an automotive drive shaft system is studied in this paper. During the analysis, the friction between the steel ball and the arc raceway is regarded as the friction between a sphere and an arc raceway surface. In order to describe the friction state more accurately, this paper proposes a correction coefficient to modify the distribution function of contact asperities in the plane, and obtains the distribution function of contact asperities between the sphere and the arc raceway surface. The correction coefficient is related to the load, the size parameters and the material parameters of the steel ball and the raceway. Then based on the modified distribution function, the fractal models of the friction coefficient, the tangential force (the friction force) and the normal contact load between the steel ball and the raceway are established. Finally, the correction coefficient is verified by the finite element model, while the relationship between the correction coefficient and the load, the relationship between the friction force and the normal contact load, and the relationship between friction coefficient and fractal parameters are analyzed through numerical examples.
Feng, Huayuan, Li, XiHua
Bollinger Motors showcases second-gen Class-3 EV prototypes19AUTP11_1611/1/2019
Bollinger Motors recently unveiled its second-generation Class-3 EV prototypes. The start-up, based in Ferndale, Michigan, revealed the latest beta of its B1 SUV and B2 truck prototypes, highlighting the amount of in-house engineering and design. As a Class 3 (GVWR 10,001 to 14,000 lb.) vehicle, the Bollinger Motors truck and SUV are in the same classification as a Ford F-350 or Ram/Chevy 3500 truck. “This is the only all-electric Class 3 truck with off-road capability,” founder and CEO Robert Bollinger said of the B2. “Our beta version vehicles look very much like the original alpha prototype vehicle that debuted in 2017, but almost every component on our B1 SUV and B2 truck prototypes is different,” said Karl Hacken, Bollinger Motors chief engineer. The four-door B1 and B2 are identical from the C-pillar forward, with the B2 truck's 139-in wheelbase stretching 20 inches longer than the SUV. Both aluminum-bodied prototypes feature a vehicle-length 16×14-in pass-through enabled by packaging the driveline systems below the floor.
Buchholz, Kami
GKN spreads premium propshaft tech to quiet pickup cabins19AUTP10_1110/1/2019
It may seem a long way in engineering and NVH terms from premium European cars such as Audi's A5 and A7 to light duty trucks, but GKN Automotive has bridged that gap with its latest lightweight all-wheel drive (AWD) modular propshaft. Many pickups suffer a significant amount of unwanted NVH emanating from the front propshaft, with its two universal or CV joints and an interconnecting shaft positioned below and close to the passenger cabin. But now GKN Automotive has “re-characterized” its premium car driveline system to an entirely different vehicle category. “With a traditional truck front propshaft, the level of noise entering the cabin is perceived as a drone,” explained Michael Miller, GKN's propshaft product technology manager. “We've worked on applications of our new technology where the cabin NVH levels have been dramatically reduced. Positive results stem from the combination of joints used in our lightweight modular front propshaft.”
Birch, Stuart
THE LIMITATIONS OF THE UNIVERSAL JOINT0800146/25/2019
VANDERBEEK, H.
Kinematic Analysis and Simulation of the Double Roller Tripod Joint2019-01-15266/5/2019
The kinematic model of the double roller tripod joint is established in order to analyze its kinematic characteristics and provide theoretical basis for its application and improvement. By means of spatial coordinate transformation, the translational and rotational motion equations of the rollers relative to the tracks and trunnions, the motion equation of the center of the tripod and the equations of the input/output angular displacement error and bending angle are derived. The motion simulation of the double roller tripod universal joint was carried out in ADAMS so as to verify the established kinematic model. The results show that the rollers of the double roller tripod joint only have periodic translational motions relative to the tracks while the rollers have both periodic translational and rotational motions relative to the trunnions. The tripod’s center does the circular motion on the tripod plane with the angular velocity 3 times of the input angular velocity. The input/output angular displacement error and bending angle have volatility, and their fluctuating frequency are 3 times of the input rotational frequency. Hence, the double roller tripod joint is a quasi-constant-velocity joint whose rollers only do pure rolling motion in the tracks.
Qiu, Yinyuan, Shangguan, Wen-Bin
New Half Shaft Bench Test Methodology for NVH Characterization2019-01-15586/5/2019
The main purpose of this paper is to develop a reliable bench test to understand the vibratory behavior of the half shafts under applied torque comparable to an idle condition. In some cases, the half shaft path is a major factor influencing the idle vibration in the vehicle. At idle condition vehicle vibrations are caused by engine excitation and then they pass through different paths to the body structure. Half shaft manufacturers generally characterize shaft joints for their frictional behavior and typically there is no data for vibration characteristics of the half shaft under idle conditions. However, for predictive risk management, the vibratory behavior of the half shaft needs to be identified. This can be achieved from measured frequency response functions under preloaded test conditions. This bench test enables manufacturers to conduct comprehensive design of experiments on the impact of powertrain vibration input while transmitting through the half shaft into the vehicle system. This method enables the study of the half shaft at the component level, because studying the half shaft at vehicle level is difficult since other paths are present. This paper describes the bench test methodology and presents certain boundary condition challenges of the half shaft measurements, the design of the test rig and the preliminary joint behavior results on the test bench.
Siavoshani, Saeed, Vesikar, Prasad Balkrishna, Yuan, Wei, Abbas, Ahmad, Sturla, Francisco Antonio
Integrated Multi-Physics Simulation for Full-Vehicle Low Frequency NVH Optimization in HEVs2019-01-14556/5/2019
The recent automotive industry trend towards electrification has created new challenges for NVH engineers. These challenges stem from new powertrain architectures and their complex interactions, the governing control strategies which aim to optimize energy management, and new unmasked sources of excitation. Additionally, vehicle manufacturers are attempting to reduce hardware testing in order to rapidly satisfy increasing production demand and to minimize its costs. Hence, to meet the above-mentioned challenges up front in the development process of Hybrid Electrical Vehicles (HEVs) while balancing competing design objectives of drivability, durability and NVH, a simulation-led design and optimization is required. NVH problems are often the result of mechanisms that originate through complex interactions between different physical domains (flow, electromagnetic, structural/mechanical, control logic, etc.) and the assembly of individual components into a complete system. Therefore, accurate system-level integrated models are becoming a requirement to solve modern NVH problems. Combining the optimal balance between simulation and experimental data, this article describes a joint effort between Ford and Gamma Technologies to develop a general methodology to perform full-vehicle low frequency NVH analysis. Using GT-SUITE software, a non-linear multi-physics simulation model of a rear wheel drive HEV was created. The model was exercised to accurately evaluate the effects of powertrain control strategy and component selection on low-frequency NVH performance during a tip-in regeneration, downshifting and in-gear acceleration maneuvers while minimizing the computational cost.
Gomez, Llorenc Foraste, Zeman, Jonathan, Liu, Jack
Experimental Investigation of Sliding on Tripod Constant Velocity Joints2019-01-50173/13/2019
An automotive transverse transmission is articulated by mechanisms called constant velocity joints (CVJ). The joint allows the suspension to move freely. Its frictional behavior is not well known. However, the CVJ functional analysis makes it possible to identify important mechanical losses due to the friction of component elements. This article will focus on tripod side. An analysis of its behavior by designing and constructing a rig in order to qualify the sliding inside of the tulip between tracks and rollers has been initiated. Thanks to three-dimensional (3D) printing and sport camera a new approach was established.
Ripard, Valentin, Ville, Fabrice, Cavoret, Jérôme, Ruzek, Michal, Charles, Pierre, Diaby, Moussa
Optimizing Steering Column Layout and UJ Phase Angle to Enhance Vehicle Dynamics Performance2019-01-50102/5/2019
Vehicle dynamics is one of the most important vehicle attributes. It is classified into three domains, the longitudinal, vertical, and lateral dynamics. This paper focuses on optimizing the lateral vehicle dynamics which is driven by the straight ahead controllability and cornering controllability of the vehicle. One of the important parameters that dictates these sub-attributes is the steering ratio. Therefore, designing the right steering ratio is critical to meet the vehicle “specific” targets. Significant amount of work has been done by many researchers on variable steering ratio by implementing variable gear ratio (VGR) rack, active steering, and steer-by-wire systems. This paper discusses the methodology and considerations to optimize the steering ratio for a constant gear ratio rack by optimizing the steering column layout, viz., orientation and the phase angle in universal joints. A detailed analysis of steering system layout is done to optimize the steering ratio to enhance the vehicle dynamics performance. Full vehicle-level multibody dynamics (MBD) simulations are done in ADAMS® to compare the vehicle response behavior for different steering ratios in the open-loop objective tests. The Computer Aided Engineering (CAE) results show significant impact of the proposed design methodology on vehicle controllability. When the phase angle and the initial column angle are optimized for a quick on-center steering ratio, the response gains are higher, resulting in a sporty and agile feel. However, when the same vehicle is tuned for a slower on-center steering ratio, the gains are lower, resulting in a sluggish, lazy feel. This methodology can be implemented during the initial vehicle design phase to optimize vehicle performance.
Puvvula, Praneeth, Ravuri, Susheel, Dubal, Ajit, Salunkhe, Swapnil
Design and Development of a Retrofit Solution for Converting a Conventional LCV into Parallel Hybrid Electric Vehicle2019-26-01171/9/2019
In today’s scenario, the emission norms are getting stringent day by day due to an increased level of pollution. The world is shifting towards low carbon footprint which made it necessary to adopt efficient technologies with fewer emissions. The hybridization of vehicles has resulted in improved efficiency with lower emissions which can fulfil the near future emission norms. Retrofitting of hybrid components into a conventional IC engine vehicle is so far the best way to achieve better performance both economically and technologically. This research is primarily focused on the design and development of a novel retrofit solution of P3x architecture for the light commercial vehicle. This retrofit solution is different from other hybrid solutions in terms of powertrain. It contains an innovative add-on powertrain along with the existing powertrain. This additional powertrain consists of a pair of helical gears followed by a chain and sprocket as a coupler for traction motor. The newly designed powertrain provides 5 different hybrid modes namely engine only mode, electric only mode, motor assist mode, battery charging mode and regenerative braking mode. The retrofit work also focuses on packaging design of hybrid components into chassis ensuring that it can sustain all load transferring from road along with additional weight without failure. To demonstrate the practical applicability of this indigenous powertrain with P3x hybrid configuration, a prototype has been developed and functionally tested on chassis dynamometer. The driving performance and fuel economy of the developed prototype were virtually tested for MIDC drive cycle. The results demonstrate a noticeable improvement in fuel economy and increase in payload compared to conventional ICE vehicle.
Kumar, Ravindra, Kaundinya, Ashwin Subramanian, Shah, Ravindra, Ghugal, Swapnil, Kale, Jyoti Ganesh, Thorat, Vivek, Barik, Saroj, Shinde, Sanket
Torsional Fluctuations Consideration while Design of Synchro Rings2018-01-18239/10/2018
In today’s manual transmissions of car, gearshift system requires high performance with particular emphasis on low effort, minimal travel and positive feel. To meet these targets, a high capacity multi cone synchronizers along with higher co-efficient of friction material used for lower gears. The design of synchronizer with these specifications is influenced by torsional fluctuations from engine. Excessive torsional vibrations leads to wobbling of synchro rings within the peripheral clearances with surrounding parts. Wobbling leads to abrasion wear of frictional area of synchro ring causing grating or crashing noise of gears during shifting. This paper presents the optimization of the multiple cone synchronizer design exposed to excessive torsional vibrations and validation of the same on test bench during development stage instead vehicle level validation.
Tawhare, Nitin, Aswale, Dhananjay, Ponkshe, Makarand
GKN turns the CV joint inside-out18AUTP09_099/1/2018
GKN Driveline is developing an innovative driveshaft concept that literally turns inside out the traditional configuration of the constant-velocity joint (CVJ), bringing potential benefits to both high-performance rear-wheel-drive vehicles-and future electric vehicles (EVs). In a conventional design, CVJ housings face outward from the sideshaft, while the sealing systems on each end face inward; GKN has been testing a layout in which the CVJ reverses the positions of these components within a sideshaft system, integrating the CVJ housings within the sideshaft itself.
Birch, Stuart
Investigation on Dry-clutch Transmissibility Characteristic for Vehicle Launch Shudder2018-01-12254/3/2018
Vehicle launch shudder is the terminology used in automotive industry to describe severe longitudinal oscillation during clutch engagement under start-up condition. This paper presents and implements detailed investigation for dry-clutch engagement and disengagement process, in order to deeply analyze vehicle launch shudder phenomenon which seriously deteriorates ride comfort. Firstly, diaphragm spring and cushion spring and link strip, which are three elastic components related to dry-clutch engagement and disengagement process in axial direction, are studied for their elastic properties, respectively, to obtain relationship between load and deflection. The elastic properties of these three elastic components are taken into considerations to establish nonlinear relationship between release bearing travel and clutch clamp force. Then, based on multi-body system dynamics theory, the lumped mass method is used to model the powertrain of front-engine and front-wheel-drive vehicle equipped with manual transmission, six-degree-of-freedom powertrain torsional vibration model is used to simulate vehicle launch shudder phenomenon numerically, and the performance of vehicle launch is evaluated by shock extent and dissipated energy. The speed of release bearing travel is used to reflect different launch intentions: fast launch and normal launch and slow launch. Finally, by comparing evaluation parameters of these three launch modes, it can be known that the longer synchronous moment or release bearing travel time, the smaller shock extent, and the better launch performance, but dissipated energy is negatively correlated with shock extent. Through the research of this paper, the launch shudder during dry-clutch engagement process is analyzed, which can provide theoretical references for structural optimization and launch control strategy.
Yuan, Renfei, Wu, Guangqiang
The Effect of Outer Ring Distortion on Wheel Bearing Friction Torque2017-01-25219/17/2017
Wheel bearing friction torque (“drag”) directly contributes to vehicle fuel economy and CO2 emissions. At the same time, one of the most important factors for long-term durability of wheel bearings is effective seal performance. Since these two factors are often in conflict, it is important to balance the desire for low friction with the need for optimal sealing. One factor that affects wheel bearing sealing performance is the distortion of the outer ring that occurs when the bearing is mounted to the steering knuckle with fasteners. Minimizing this distortion is not just important for sealing, however. This paper explores the relationship between the outer ring distortion and the resulting friction torque. A design of experiments (DOE) approach was used in order to study the effects of the fastening bolt torque, constant velocity joint (CVJ) fastening torque, and outer ring distortion on component-level drag. The correlation shows the importance of maintaining raceway roundness in order to both improve sealing effectiveness and reduce friction within the wheel bearing.
Scherer, Stacey
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
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
Driveline Boom Noise Reduction through Simplified FEM Approach2017-26-02151/10/2017
In today's competitive automobile marketplace with reduced vehicle development time and fewer prototypes/tests, CAE is playing very crucial role in vehicle development. Automobile environment demands ever improving levels of vehicle refinement. Performance and refinement are the key factors which can influence the market acceptance of vehicle. Driveline is one of the key systems whose refinement plays critical role in improved customer satisfaction. Because of the virtue of the driveline functionality, driveline induced noise and vibration are the most common issues in the AWD vehicle development programs. Refinement of the drive line needs complicated nonlinear full vehicle CAE MBD models for the evaluation of driveline induced noise and vibration responses at different operating conditions [1]. In this paper a simplified approach is adapted for solving the Noise & Vibration issue which has been identified at the prototype testing level of an AWD vehicle development. Linear finite element method is used as a basic tool in identifying the root cause and propose the design solution. In presented work full flexible FE driveline model was built for modal analysis and the ODS was matched with test behavior. After establishing the correlation between the FE and Test, different system variables were optimized to reduce the system level response. Later these solutions were evaluated for seat vibrations and cabin noise levels. This technique can be used where the time, resources and system inner details are not available or those are limited to build the complete nonlinear CAE models. With this simplified approach it was possible to quickly resolve the driveline induced N&V problem.
Krishna, Kodali Ajay, Patil, Sanjeev
CVJ and Knuckle Design Optimization to Protect Inboard Wheel Bearing Seals from Splash2016-01-19569/18/2016
For higher mileage vehicles, noise from contaminant ingress is one of the largest durability issues for wheel bearings. The mileage that wheel bearing sealing issues increase can vary due to multiple factors, such as the level of corrosion for the vehicle and the mating components around the wheel bearing. In general, sealing issues increase after 20,000 to 30,000 km. Protecting the seals from splash is a key step in extending bearing life. Benchmarking has shown a variety of different brake corner designs to protect the bearing from splash. This report examines the effect of factors from different designs, such as the radial gap between constant velocity joint (CVJ) slinger and the knuckle, knuckle labyrinth height and varying slinger designs to minimize the amount of splash to the bearing inboard seal. This report reviews some of the bearing seal failure modes caused by splash. This study also discusses the test methodology to confirm the robustness of the various designs and provides information on the effectiveness of different features to protect the corner from splash.
Sutherlin, Robert G., Reed, Douglas
Impact of Nanofluids on Heat Transfer Performance of a Motorcycle Radiator2016-01-01884/5/2016
In the present work, the effect of various nanofluids on convective heat transfer performance in an automotive radiator was analyzed based on measured nanofluid properties. Al2O3, TiC, SiC, MWNT (multi-walled nanotube) and SiO2 nanoparticles ranging between 1 and 100 nm in size were dispersed in distilled water to form nanofluids. An ultrasonic generator was used to provide uniform particle dispersion in the fluid and keep the mixture stable for a long period of time. The impact of various particle types and their volume concentration on fluid properties such as density, thermal conductivity and viscosity were experimentally analyzed. It is observed that the nanofluid properties increased with the increase in particle volume concentration. TiO2 nanofluids were observed to show the highest increase in density (2.6% higher than the base fluid at a 1% vol. concentration) and also the largest enhancement in thermal conductivity (7.5% augmentation at 1% concentration). SiO2 nanofluids exhibited to be the most viscous, with a 47% increase in viscosity over base fluid at a 1% vol. concentration. Empirical correlations were then used to predict the convective heat transfer coefficient for laminar nanofluid flows. The effect of nanoparticle volume concentrations on Nusselt number and heat transfer coefficient were investigated. The results showed that SiO2 nanofluids had the highest enhancement in the heat transfer coefficient. At a Reynolds number of 1000, the enhancement of heat transfer coefficient over the base fluid for a 1% volume concentration of SiO2, Al2O3 and TiO2 nanofluids are 35.3%, 35.1% and 30.5% respectively.
Mathivanan, Elankathiravan, Liu, Liping
Virtual Drivetrain Simulation Using Adams View and Correlation with Test2016-01-13614/5/2016
Reducing the vibrations in the drivetrain is one of the prime necessities in today’s automobiles from NVH and strength perspectives. The virtual drivetrain simulation methodology to predict the driveline induced excitations transmitted to vehicle is developed for three cylinder engine using Adams View. The obtained mount forces from Adams dynamic simulation is correlated with the measured test data at vehicle level and the good correlation is observed. Paper discusses on the methodology of virtual drivetrain using Adams view and the correlation of measured dynamic mount forces with simulation results. This correlation gives the confidence that the developed simulation methodology can be used to get the mount forces of different orders from drivetrain.
Londhe, Abhijit, Yadav, Vivek, Kannaiyan, SenthilKumar, Karthikeyan, Krishnan, Reddy, Ganeshan
Offset Driveline for Tractors2016-28-01282/1/2016
Tractors with 4WD drive perform better in slick, off road or muddy conditions (especially in Agricultural and constructional Field applications) where torque is required at all the wheels. The purpose of four wheel drive or all-wheel drive is to transmit power to all the wheels. In case of 2WD the power from engine is transferred to the rear wheels of a tractor through transmission. But in case of 4 WD tractors and construction equipment, power from engine is transferred to the front wheels through drop box and the driveline (propeller shaft). This Paper describes the need of an offset driveline where there is an offset between the Drop box output shaft center and the front axle input shaft center. This offset is the result of zero keel angle of the tractor. In order to maintain zero keel angle and transfer power to front wheels, an offset driveline with three shafts has been design &developed. Additionally a concept for an offset driveline which has been experimentally proven for tractors and construction equipment is also discussed.
Chaudhari, Navneet, Sethi, Suvendu Kumar, Srinivasa, Rao
Companion Flanges, Type A (External Pilot) and Type S (Internal Pilot)J1946_201601 (Current)1/26/2016
This SAE Standard specifies the nominal dimensions and tolerances which affect the interchangeability between companion flanges and mating parts. The flanges covered by this document are designated type A and type S. The type A flanges are equivalent to type A ISO 7646. The type S flanges are equivalent to the type S ISO 7647. Type A is an external (male) pilot construction and type S is an internal (female) pilot construction. These flanges are not interchangeable. Dimensions not specified are left to the discretion of the component manufacturer.
Drivetrain Standards Committee
Universal Joint End Yoke Connection (Earwork)J2301_201601 (Historical)1/15/2016
This document specifies the main dimensions and tolerances, which affect interchangeability between end yoke earwork for the most common North American used universal joints. Dimensions and tolerances of the mating universal joints are left to the discretion of the universal joint manufacturers. The term “Earwork” refers to the configuration and geometry defining end yoke connections directly provided for universal joint cross attachment of drivelines. Earwork for certain styles of universal joint connections and flange connections have for a long time been proprietary to certain manufacturers. Over years of usage, proprietary rights have expired and the industry, as a whole, has used these earworks as standard. In an effort to tabulate some of the long established practices, the following SAE Recommended Practice has been compiled. Manufacturers do from time to time, as the need arises, change tolerances or fits to better enhance component performance. This document has been prepared as a reference, and is a snap shot of current technology. The half round (strap connection), full round (retainer plate type connection) and wing type connection are covered in this document. For an understanding of these end yoke styles, please refer to SAE J901. There are earwork forms that still are proprietary and are not covered by this document.
Drivetrain Standards Committee
Front-Wheel-Drive Constant Velocity Joint Boot SealsJ2028_201601 (Current)1/15/2016
This SAE Recommended Practice outlines the qualification testing and performance related criteria of elastomeric boot seals used in constant velocity joint applications. These applications are referred to as front- wheel-drive halfshafts or axles, but can also be utilized in rear-wheel-drive halfshaft applications. For additional information regarding CV joint systems and their applications refer to SAE AE-7 “Universal Joint and Driveshaft Design Manual.”
Drivetrain Standards Committee
Retrofitting of an Electronic System to Control and Data Acquisition in an Automotive Dynamometer for Didactic Use2015-36-02819/22/2015
Integrated controls for commercial dynamometers do not have appropriate characteristics to perform research and teaching tasks. These are developed to perform quick tests and its logic is prepared to obtaining the information in accordance with the technical standards. This way, the use for research is hindered because it does not have an interface that allows a refinement to the desired data ranges, t data sampling and the type of load that is applied. Its use for teaching is limited because these "standard" controls does not allow to analyze or to determine engines characteristics that are not covered through tests specified by the standards, so the use of this tool as an important part in professional training formed by the institution. The development of a system control to the electromagnetic brake and capture of torque and rotation data will allow better use of dynamometers for research and teaching, providing to the students the knowledge of the control system itself and data acquisition where parameters such as temperature and pressure can be added, improving the accuracy of torque and power measurements. This system will be made available to other educational and research institutions interested in the use of a control and data acquisition system designed for teaching and research in the engine area, with a low cost of development and operation.
Vandresen, Marcelo, Silveira, James, Pereira, Milton, Chaplin, Richard, Fernandes, Gustavo
Experimental Investigation of Effect of Driveline Torsional Fluctuations on Overall NVH Performance of the Vehicle2015-01-21926/15/2015
Meeting various customer(s) requirements with the given automotive product portfolio within the stipulated time period is a challenge. Design of product configuration matrix is an intelligent task and it requires information about vehicle performance for different configurations which helps in deciding the level of new development. Most often the situation arises, particularly in the field of NVH, to strike the right balance between engine power and structural parameters of the body. The sensitivity of engine power on the overall NVH behavior is the key information necessary to take major business decisions. In this paper, the effect of change in torsional fluctuation of the engine on the NVH behavior of the rear wheel drive vehicle is experimentally studied. The torsional fluctuation of the driveline is given as an input with the help of an electric motor to the existing test vehicle at its differential end and the current NVH levels are measured. A test rig is built to change the levels of torsional vibration input to the vehicle. The threshold level of torsional fluctuation for the given vehicle structure is obtained by taking into account the target values of tactile vibration and subjective perception. The results are very useful in deciding the acceptable level of change in engine power without carrying any structural change. Also, for a given power, the set of structural changes necessary in the body and suspension linkages to meet the NVH criteria can be studied. The procedure is also extended to an all-wheel drive vehicle with the help of a two wheel drive chassis dynamometer. Obtaining subjective perception of the vehicle NVH even before making the vehicle of target configuration is an inherent advantage of the proposed technique. A good correlation is achieved with the objective results and subjective perception.
Rao, Manchi Venkateswara, Frank, Jos, Raghavendran, Prasath
Study on the Bending Vibration of a Two-Piece Propeller Shaft for 4WD Driveline2015-01-21746/15/2015
Currently, four wheel drive (4WD) system is widely used in Sports Utility Vehicle (SUV) due to the increasing demand of fuel efficiency and dynamic performance by customers. However, propeller shaft consisting of different universal joints and tubes on 4WD vehicle easily induces low frequency bending vibration. This paper analyzes the characteristics of driveline bending vibration of a 4WD vehicle and provides control methods to reduce the low frequency vibration caused by propeller shaft bending resonances. Firstly, the driveline bending vibration model of the 4WD vehicle is established using FEA method and the natural frequencies are calculated. Secondly, the influence parameters, such as universal joint, relative length of two-piece propeller shaft, and tube diameters, on bending frequencies are analyzed by both FEA analysis and physical testing. Thirdly, the bending vibration responses for several propeller shafts with different lengths and diameters are predicted by unit force input at PTU shaft output. Finally, the control methods to reduce propeller shaft bending vibration are proposed. The analysis results are validated by testing and both reach good consistency.
Xia, Yuanfeng, Pang, Jian, Zhou, Cui, Li, Hongcheng, Li, Wenjuan
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
Torsional Vibration Analysis of Powertrain and Driveline Using Finite Element Method2015-01-22876/15/2015
Among the lower frequency vehicle NVH problems, booming noise is one of the most concerned issues. One of the most common booming noise sources is the torsional vibration of the powertrain and driveline for rear-wheel drive and four-wheel drive vehicles. The solutions for this problem are either to use a torsional dynamic absorber or to use a lower stiffness clutch. Both solutions require the modal frequency of the torsional vibration mode of the powertrain and driveline. At early design stages, vehicle prototype is not available for measuring this frequency. Analytical method is usually used to calculate this frequency. Currently, mostly used method is the so-called 1D method in which the whole powertrain and driveline are represented by one-dimensionally connected disks (lumped inertia) and shaft (lumped stiffness). However, those lumped parameters are not always available at early design stage. In this paper, a method using finite element models is presented. In this method, all components in the powertrain and driveline are modeled by either three-dimensional solid mesh or two-dimensional shell mesh. The component FE models are connected together to construct the model for the whole powertrain and driveline based on the physical connections between them. The constructed FE model is used for modal analysis by MSC/Nastran. The results of the modal analysis will have the information of the torsional mode. To demonstrate this method, a rear-wheel drive vehicle will be included in the paper as a case study. Results of the modal testing and noise measurements will also be presented.
Deng, Yaqiong, Zhao, Yanjing, Zeng, Xiandi
Brake Noise Prediction Using Altair Multi-Body Simulation2015-36-00025/13/2015
The level of noise transmitted to the passengers of a vehicle can drastically impact a passenger's comfort. Brake noise will give the customer an impression of poor product quality and can thus damage the quality image of the company. Within the automotive industry, the study of mode coupling instability by the use of FEM and modal complex analysis is widespread to reduce this phenomenon. In this paper an alternative method is presented, where potential brake noise issues are predicted by the use of a time transient integration using multi-body system analysis. The simulation model contains a nonlinear contact description, bushing, flexible bodies and the axis kinematics of the vehicle. Transient results are transformed by Fourier for a frequency domain study. The parameters that can be varied for the prediction analysis are brake pressure, vehicle speed, friction laws, system damping and bushing properties. The advantages of the multi-body system analysis approach are in the direct consideration of the non-linearity's which are significant within certain frequency ranges. The multi-body system analysis approach also provides a further method to confirm results from the complex modal analysis and thus increases the informational value of the numerical predictions. Simulations variant results will be presented and discussed and enhancements will be proposed.
Sundaresh, Keshav, Leila, Felipe Moretti
Car-in-the-Loop Complete Vehicle Test Rig2015-01-06474/14/2015
During the last years mechatronic systems developed into one of the biggest drivers of innovation in the automotive industry. The start of production of systems like dual clutch transmission, lane departure warning systems and active suspensions proves this statement. These systems have an influence on the longitudinal, steering and vertical dynamics of the vehicle. That is why the interaction on vehicle level is crucial for an optimal result in the fields of efficiency, comfort, safety and dynamics. To optimize the interaction of mechatronic systems, in this paper a new test rig concept for a complete vehicle is presented. The so-called Car-in-the-Loop-concept is capable of realistically reproducing the loads, which act on the powertrain, the steering and the suspension during a test drive. The resulting advantages are the possibility to exactly reproduce test procedures, the independence from weather conditions and a minimization of the risk of human injuries during testing of safety functions. A prototype of this concept, which includes parts of the powertrain, the steering and the chassis corresponding to the left front side of a BMW Mini Countryman, was built at the lab of the Institute for Mechatronic Systems in Mechanical Engineering of the TU Darmstadt. A test rig shaft connects the wheelhub of the BMW Mini Countryman to actuators, which generate realistic loads corresponding to the current driving situation. To provide the needed adaptiveness for the steering and suspension movement constant velocity joints and ball-spline supported length compensations are included in the test rig shaft. A highly dynamic test drive is being reproduced on the prototype to prove the functionality of the Car-in-the-Loop-concept.
Fietzek, Rafael, Rinderknecht, Stephan
Creation of Halfshaft Joint Selection Tool in Terms of Strength and Life Calculations for FWD Vehicles2014-01-23299/30/2014
This study is inspired by the calculations and validations required for front wheel drive (FWD)-halfshaft joint selection. To increase design efficiency with decreased response time; a tool is required to validate calculations of strength based on maximum impact torque and endurance life based on corresponding vehicle usage. The tool has been developed to cover both strength and endurance life calculations. It also includes a constant velocity joint (CVJ) size library in order to compare different cases and to be able to see opportunities between different sizes. Validation and correlation has been completed using road load data from actual vehicles and standard load cycle (SLC) rig test results. This study introduces a more efficient methodology that will help the user select a joint that is sized best for strength and cost. After the completion of the study, one can be assured that the joint selected is the proper size-for all kinds of FWD vehicles.
Kaya, Sibel, Ayber, Barış
Shaft EndsJ501_201406 (Current)6/5/2014
Materials, Processes and Parts Council
Analysis and Modeling of Transmission Efficiency of Vehicle Driveline2014-01-17794/1/2014
This work analyzes the transmission efficiency of vehicle driveline including the gearbox, universal transmission and differential. Based on the structure of transmission, mathematic models are built to analyze transmission's characteristics. However, an experiment reveals the limitation of this method. Then, the paper statistically analyzes the experimental data and mainly analyzes the influencing factors. Then Neural Network is used to build the efficiency model. A method called “filling data and gradually extrapolating” is used when building neural network model. Finally, the neural network model is used in the simulation of fuel consumption. The conclusion is Neural Network model can imitate the transmission efficiency of vehicle driveline efficiently, but its internal structure is not clear so other modeling methods are needed to be found.
Zhang, Wei, Guo, Xuexun
Finite Element Method Limitation for Natural Frequencies Determination of Automotive Components2013-36-030910/7/2013
Engine downsizing is the use of a smaller engine in a vehicle that provides the power of a larger one. It is the result of car manufacturers attempting to provide more efficient vehicles by adding modern technologies, for instance, turbochargers, direct injection and variable camshaft. The smaller engine is also lighter and provides torque and power with similar performance to a much larger engine. However, the downsizing technique may lead to undesirable vibration effects on the driveline, such as structural damaging, vibration fatigue failure and extra noise. All these issues are related to natural frequencies investigation and they are often determined through the finite element method together with experimental tests during the product development phase. This work presents the finite element method limitation for natural frequencies determination of automotive components and a possible solution for the issue.
Souza, Thales Sardinha Garcia, Novo, Felipe Moura Fontes, de Souza, Mauro Moraes, Savoy, Juliano
Conceptualization and Implementation of an AWD Parallel Hybrid Powertrain Concept2013-01-14484/8/2013
The Deep Orange [1] initiative is an integral part of the automotive graduate program at Clemson University International Center for Automotive Research. The initiative was developed to provide the graduate students with hands-on experience of the knowledge attained in the various engineering disciplines and related disciplines (such as marketing and human factors psychology). For the 3rd edition of Deep Orange, the goal was to develop a blank sheet hybrid mainstream sports car concept targeted towards the Generation Y (Gen Y) market segment. The objective of this paper is to elaborate on the overall development process and the technology that was created and integrated. A unique all-wheel-drive (AWD) parallel hybrid concept was derived based on extensive analyses of the Gen Y market. The data revealed that Gen Y, as an environmentally conscious generation, is willing to invest in sustainable powertrain technologies and also has a significant interest in all-wheel-drive. Based on these findings, a through-the-road parallel hybrid powertrain concept with a manual transmission was conceptualized. The powertrain architecture comprises of a Front-Wheel-Drive (FWD) concept using a downsized turbocharged 4-cylinder Internal Combustion Engine (ICE) and a Rear-Wheel-Drive (RWD) concept using an electric machine. This configuration allows for regenerative braking, all-wheel-drive and power boost functionality. In the early development phase of the project, simulation models were developed for sizing the powertrain components using model-based design tools in order to achieve functional targets while carefully balancing cost, weight and design-space. This paper will elaborate on how the unique hybrid powertrain setup was developed based on a holistic systems engineering approach incorporating competing aspects such as performance, fuel economy, exterior/interior design and powertrain component packaging.
Venhovens, Paul, Pisu, Pierluigi, Prucka, Robert, Makkar, Bhavuk, Frommann, Patrik, Sonavane, Tejas, D'Amico, Chris
Experimental Study of a Pre-Chamber Jet Igniter in a Turbocharged Rotax 914 Aircraft Engine2013-01-16294/8/2013
An experimental study is performed to investigate the possibility of relaxing the octane requirement of a Rotax 914 engine equipped with a pre-chamber jet ignition system. A pre-chamber jet igniter with no auxiliary fuel addition is designed to replace the spark plug in cylinder two of the test engine and is evaluated across engine speeds ranging from 2500 to 5500 RPM. Experiments are performed across both normally aspirated and boosted configurations using regular 87 AKI gasoline fuel. Normally aspirated results at 98 kPa manifold absolute pressure show a 7-10° burn rate improvement with the jet ignition combustion system. Tests to determine the maximum load at optimal combustion phasing (no spark retard) are then conducted by increasing boost pressure up to maximum knock limits. Boosted jet ignition results demonstrate that 17 bar IMEPn can be achieved using 87 AKI gasoline fuel, which is the highest documented load achieved with this combustion system at stoichiometric conditions without dilution. A ~ 3 bar IMEPn increase over spark ignition combustion is also observed in the same test engine, corresponding to a ~25 kPa boost pressure increase across the speed range. When comparing the 87 AKI jet ignition results to those of the baseline spark ignition OEM engine which requires 100 low lead (≻ 99.5 MON) aviation gasoline, experimental results highlight that peak torque at 4500 RPM can be matched, however peak power is slightly reduced by 9% at 5500 RPM. Hence, it is estimated that this particular jet igniter offers a ≻ 10 octane number improvement over the baseline spark ignition system. This demonstrates that retrofitted pre-chamber jet igniter technology offers the general aviation industry a potential means of relaxing engine octane requirement. Experimental burn rate results and visual evidence of the jet impingement on the piston crown confirm that further pre-chamber nozzle and jet optimization are required to achieve the full knock limit benefits of this combustion system as demonstrated in the literature. However, results thus far are very encouraging for future lead-free gasoline aviation engines as well as boosted automotive powertrains as engine downsizing grows in popularity.
Anderson, Eric K., Attard, William P., Brown, Adam, Litke, Paul, Grinstead, Keith, Hoke, John
The Effect of Multi-Universal Coupling Phase on Torsional Vibration of Drive Shaft and Vibration of Vehicle2013-01-14904/8/2013
Torsional vibration of drive shaft has great influence on the vibration of vehicle. Reasonable phase arrangement of multi-universal coupling can attenuate vibration. In this paper, theoretical model of drive shaft with planar multi-cross universal coupling was established; the optimization scheme of the phase arrangement of multi-cross universal coupling was presented. The results of test validation and simulation show that the optimization scheme is effective and reasonable. The results of test validation and simulation show that the optimization scheme was effective and reasonable and the optimized scheme could solve the abnormal vibration on floor. Arranging phases of universal joints reasonably is very significative for attenuate the torsional vibration of drive shaft and the floor vibration.
Wu, Guangming, Shi, Wenku, Chen, Zhiyong
Development of Active Vibration Control System for Driveshafts2013-01-00283/25/2013
Driveshafts are one of the most important components in power-train system in vehicle as it transfer torque generated from engine to wheels in high speeds. As a driveshaft is in rotating condition vibration problems can be observed by resonance or external force. The generated vibration problems in vehicles cause discomfort to drivers whenever they are driving. To solve these problems, there have been many attempts to control such generated vibration in vehicle. In this study, vibration control system for driveshaft has been proposed to reduce the generated vibration. The smart damper for the system is designed considering to be implemented in driveshaft with quick response and a compact size. The damper is consists of electromagnets so it can response relatively quickly compared to other damping system. When a driveshaft reaches to its natural frequency, vibration control system with the damper is activated to minimize the vibration as it shifts its natural frequency region. The test results show that the magnitude of vibration is reduced and the natural frequency region is shifted with quick response as the control system is activated.
Bak, Jeong-Hyeon, Lee, Kwang-Hee, Park, Jeong-Lyul, Lee, Chul-Hee, Lee, Eun-Sang, Kim, Nam-Kyung
An Innovative Lightweight Solution for Connect a Prop Shaft with a Differential2012-36-028410/2/2012
Prop shafts and differentials have been improved continuously. They are getting even more efficient and more lightweight. But the interface between these two parts looks still the same since more than 50 years what gives us a great chance for improvement. Rear or front axle differentials are currently fitted with a flange. This flange is necessary to connect the prop shaft frictionally with the differential during the final assembly. The substitution of universal joints by constant velocity joints gives the possibility of replacing a flange connection by a compact, lighter screwed connection. This paper will present a new single piece screwed solution which fits perfectly on the demands of modern all- / rear - wheel driven cars.
Karl, Christoph, Haas, Roman
Control Strategy for the Longitudinal Degree of Freedom of a Complete Vehicle Test Rig2012-01-02324/16/2012
The Institute for Mechatronic Systems in Mechanical Engineering (IMS) designed a concept for a test rig, which enables the simulation of longitudinal, steering and vertical dynamics for a complete vehicle under laboratory conditions. The main part of the test rig concept is a shaft, which contains three constant velocity joints and two ball-spline supported length compensations. It connects the wheel hub of the test car to an electric motor. In addition a linear actuator is mounted to the middle part of the shaft and a hydraulic actuator replaces the suspension strut. These actuators can load the longitudinal, steering and vertical degree of freedom of the test car according to simulated driving maneuvers. A prototype of this concept is being built at the IMS lab. Beginning with a precise explanation of the test rig concept this paper discusses the control strategy for the rotational speed of the wheel hub of the car mounted on the test rig based on a simulation. The following issues have to be considered. The shaft connecting the electric motor to the wheel hub has an elasticity, which cannot be neglected. As the actuator and sensor position are not collocated and this is an unrestrained degree of freedom, a model based control approach like for instance pole placement is required to assure stability. In this context the effect of the placement of the poles on the longitudinal dynamics will be evaluated. Another factor, which has influence on the longitudinal dynamics, is the torque in the vehicle power train, which is regarded as a disturbance. In a vehicle it can only be observed over the bus system with insufficient accuracy. For this reason a disturbance feedforward strategy is explained and the influences of the accuracy of the power train torque are reviewed.
Rinderknecht, Stephan, Fietzek, Rafael, Meier, Torben
Correlation between Virtual and Physical Test for Offset Deformable Barrier Crash for SUV2011-26-00911/19/2011
In the present age automotive manufacturers are putting their effort to reduce product cycle time and product cost. This has been possible with the help of Computer Aided Engineering (CAE). CAE is playing vital role in design and develop of new products as well as up gradation of existing one to meet new safety regulations and customer requirements. It has become increasingly accepted that use of well-developed, CAE models present the best approach for upfront prediction of vehicle behaviour. The ability to simply predict trends is no longer acceptable. Meaningful results can be derived, and projections made, from the CAE model, only if the CAE results are correlated against physical tests. Correlation between Simulation and Physical test is key, to build confidence on product development with virtual validation. This paper discusses the correlation between the CAE and Physical Test for offset deformable barrier crash for 4 Wheel Drive (4WD) Sports Utility Vehicle (SUV) vehicle. It also discusses some feasible methods like modelling of CV joint, strain rate effect, failure modelling to improve the correlation. Deformation pattern and acceleration and velocity pulses were compared after incorporating the failures of physical test in computer simulation.
Jain, Ritesh Kumar, Sharma, Manish
A Sub-Hertz, Low-Frequency Vibration Isolation PlatformTBMG-90111/1/2011
One of the major technical problems deep-space optical communication (DSOC) systems need to solve is the isolation of the optical terminal from vibrations produced by the spacecraft navigational control system and by the moving parts of onboard instruments. Even under these vibration perturbations, the DSOC transceivers (telescopes) need to be pointed l000’s of times more accurately than an RF communication system (parabolic antennas).
Power Train Model Refinement Linked with Parameter Updating Through Nonlinear Optimization2010-01-14216/9/2010
In the virtual development process validated simulation models are requested to accurately predict power train vibration and comfort phenomena. Conclusions from refined parameter studies enable to avoid costly tests on rigs and on the road. Thereby, an appropriate modeling approach for specific phenomena has to be chosen to ensure high quality results. But then, parameters for characterizing the dynamic properties of components are often insufficient and have to be roughly estimated in this development stage. This results in a imprecise prediction of power train resonances and in a less conclusive understanding of the considered phenomena. Conclusions for improvements remain uncertain. This paper deals with the two different aspects of model refinement and parameter updating. First an existing power train model (predecessor power train) is analyzed whether the underlying modeling approach can reproduce the physical behavior of the power train dynamics adequately. Thereby especially rotational irregularities of the power train causing the low frequency boom noise are considered. Based on the example “tire model”, different model improvements are investigated by means of sensitivity analysis. Efficient measures are chosen to validate the quality of the results in comparison to test results. A manual approach by a stepwise analysis of each parameter is time consuming and often does not lead to accurate results due to nonlinear model behavior. Furthermore, the interdependence of an increasing number of parameters can hardly be managed manually. Therefore, the second part of the paper focuses on parameter identification methods through nonlinear optimization based on full vehicle measurements. The whole optimization process - from the formulation of the objective function to the analysis of the results - is discussed. The model improvements as well as the parameter optimization are based on vehicle tests of an all-wheel driven passenger car. The combination of model refinement and updating with non linear optimization methods demonstrates an effective approach to fine-tune simulation models for an optimum support in the product development process.
Girstmair, Josef, Priebsch, Hans H., Reich, Franz, Zehetner, Josef
Steerable Hopping Six-Legged RobotTBMG-80806/1/2010
The figure depicts selected aspects of a six-legged robot that moves by hopping and that can be steered in the sense that it can be launched into a hop in a controllable direction. This is a prototype of hopping robots being developed for use in scientific exploration of rough terrain on remote planets that have surface gravitation less than that of Earth. Hopping robots could also be used on Earth, albeit at diminished hopping distances associated with the greater Earth gravitation.
More About Reconfigurable Exploratory Robotic VehiclesTBMG-55258/1/2009
Modular exploratory robotic vehicles that will be able to reconfigure themselves in the field are undergoing development. These vehicles at the initial concept stage were described in “Reconfigurable Exploratory Robotic Vehicles” (NPO-20944), NASA Tech Briefs, Vol. 25, No. 7 (July 2001), page 56. Proposed for use in exploration of the surfaces of Mars and other remote planets, these vehicles and others of similar design could also be useful for exploring hostile terrain on Earth.
Development of a Multi-Body Systems Approach for Analysis of Launch Shudder in Rear Wheel Driven Vehicles2009-01-20735/19/2009
Driveline shudder is a low-frequency (10 Hz - 30 Hz) vibration issue of vehicles that can occur under various test conditions. Specifically, launch shudder is an issue that can be prevalent under vehicle take-off conditions. Factors that typically contribute to launch shudder include stick-slip excitation of friction materials (clutches) and driveline excitations, in particular, on rear wheel drive (RWD) vehicles. Shudder caused by the driveline excitation is generally related to the universal joints (Cardan joints) in the driveline system. In this case, the u-joint forces and kinematics induce a 2nd order excitation when operated under a driveline angle. This document focuses on launch shudder phenomena resulting from driveline system excitation on a RWD vehicle. An initial treatment of the physics governing launch shudder and typical factors influencing the shudder levels in vehicle are provided. Following this, the development of a multi-body systems (MBS) based approach is described. The results from the model are shown to correlate well with experimental measurements on a test vehicle. Upon demonstrating good correlation, the MBS model is utilized to conduct sensitivity analyses with respect to key design factors that influence launch shudder. Finally, the results are summarized and suitable conclusions provided.
Wellmann, Thomas, Govindswamy, Kiran
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