Vacuum suction cups are used as transforming handles in stamping lines, which are essential in developing automation and mechanization. However, the vacuum suction cup will crack due to fatigue or long-term operation or installation angle, which directly affects production productivity and safety. The better design will help increase the cups' service life. If the location of stress concentration can be predicted, this can prevent the occurrence of cracks in advance and effectively increase the service life. However, the traditional strain measurement technology cannot meet the requirements of tracking large-field stains and precise point tracking simultaneously in the same area, especially for stacking or narrow parts of the suction cups. The application must allow multiple measurements of hidden component strain information in different fields of view, which would add cost. In this study, a unique multi-camera three-dimensional digital image correlation (3D-DIC) system was designed

Guo, Bicheng, Zheng, Xiaowan, Fang, Siyuan, Yang, Lianxiang

The Study of Time-frequency Domain Accelerated Editing Method for Road Load Spectrum of Automobile Rubber Isolator

2022-01-073803/29/2022

In order to improve the efficiency of durability testing of automobile parts, a time-frequency domain accelerated editing method of road load spectrum of rubber mount on powertrain was discussed. Based on Stockwell Transform (ST) theory and Accumulative Power Spectral Density (APSD), a new time-frequency domain accelerated editing method (ST-APSD) was proposed. The accumulative power spectral density was obtained by ST of the load spectrum signal of automobile powertrain rubber mounting force collected by the real vehicle in the test field. Based on this, the threshold value was set to identify and delete the small damage load fragments, and the acceleration spectrum was obtained. At the same time, the existing time-frequency domain accelerated editing methods (short-time Fourier transform and wavelet transform) were used to accelerate the editing of the force load spectrum, and the editing effects of the three time-frequency domain editing methods were compared and analyzed from four

Zhu, Xijun

Evolution and Redistribution of Residual Stress in Welded Plates During Fatigue Loading

2022-01-029803/29/2022

The presence of residual stresses affect the fatigue response of welded components. In the present study of a thick welded cantilever specimen, residual stresses were measured in an as-welded A36 steel sample and in a sample subjected to a short history of bending loads where substantial local plasticity is expected at the fatigue hot-spot weld toe. Extensive XRD measurements describe the residual stress state in a large region in front of the weld toe both in an untested as-welded sample and in a sample subjected to a short load history that generated an estimated 0.01 strain amplitude at the stress concentration zone at the weld toe. The results show that such a test will significantly alter the welding induced residual stresses. Fatigue life prediction methods need to be aware that such alterations are possible and incorporate the effects of such cyclic stress relaxation in life computations.

Pineault, James, Gales, Casey, Conle, Al

Halfshaft Joints Lifetime Prediction Method and Tool Development

2022-01-029003/29/2022

This study is inspired by the technological developments across all product development areas for the elimination of physical testing based on data analytics. As one of the important driveline components, halfshaft fatigue performance is mostly limited by CV Joints life. That being the case, product development engineering teams are challenged to deal with black box CV joint designs from various suppliers and validate them for different applications. In this paper, it's mentioned about the method development of road load data usage to have robust lifetime prediction for CV joints. Instantaneous joint angles which are not possible to acquire during vehicle testing with conventional equipments are one of the main parameters for the damage rating. A solution is provided to generate a correlation between theoretical angle calculations and available parameters from the given road load data. At the end of the study, calculated CV joint fatigue life in mileage are compared with the real life

Ayber, Barış, Kaplan, Murat, Genc, Utku, ÖZEN, Erman, POSA, Chris, ATKINSON, Nancy

A study on editing method of road load spectrum of automobile rubber isolator using time-frequency domain methods

2022-01-031403/29/2022

In order to enhance the efficiency of durability testing of automobile parts, a time-frequency domain accelerated editing method of road load spectrum of rubber mount on powertrain was discussed. Based on Stockwell Transform (ST) method and Accumulative Power Spectral Density (APSD), a new time-frequency domain accelerated editing method (ST-APSD) was proposed. The accumulative power spectral density was obtained by ST of the load spectrum signal of automobile powertrain rubber mounting force which is acquired by the real vehicle in the test field. Based on the accumulative power spectral density, the threshold value was proposed to identify and delete the small damage load fragments, and then the acceleration spectrum was obtained. At the same time, the already existed time-frequency domain accelerated editing methods (short-time Fourier transform and wavelet transform) were used to edit the force load spectrum to shorten the length of the spectrum, and the editing effects of the

Zhu, Xijun, Shi, Wei, Qian, Xuepeng, Wang , Fei

An Engineering Approach to Consider Stress Concentrations in Fatigue Life Predictions on Automotive Body Structures

2022-01-030103/29/2022

This paper proposes a new procedure for more accurate durability predictions on the edges of structural components especially on notch regions. Current CAE procedures based on elemental stress often require iterative mesh refinement to correlate predictions to experimental cracking on the edges of components. The new proposed procedure is based on element nodal stress. It is first studied theoretically on a rectangular plate with different element sizes and options and demonstrates an improvement over elemental stress methods. It is then studied on multiple examples of experimental cracks and successfully predicts issues where current elemental stress methods do not. In addition, it avoids the iterative mesh refinement associated with current methods. In summary, the new method based on nodal stress is more accurate, more efficient, and improves first time through capability on the edges of structural components.

Zhang, Weidong, Pankaj, Ananta, Archak, Vijay, Guo, Mingchao

Comparing stress gradient and other concepts for fatigue analysis of notched components

2022-01-028803/29/2022

Nowadays simulation of the fatigue life is an essential part of the development of components in the automotive and machinery industry. Weak points can be identified fast and reliable with respect to stiffness, strength and lightweight. A pure virtual optimization of the design can be performed without the need of prototypes. Only for the production release a final test is necessary. A lot of parameters influence the fatigue life as the local stress, material, surface roughness, size of the component, temperature etc. Notches have the strongest impact on fatigue life, depending on radius and shape. Stresses at the notch base are increased because the load flow is forced through a reduced cross section, or changes its direction around an inwardly curved edge. But notches cause not only an increase of the local stress. Also, the local fatigue strength is increased because of a support effect from the neighboring areas, where the stress is already reduced. To account for this effect

Spindelberger, Gerhard, Gaier, Christian, Huebsch, Wolfgang

Fatigue life prediction method for rubber material based on Extreme Learning Machine

2022-01-029603/29/2022

Uniaxial fatigue tests of rubber dumbbell specimens under different mean and amplitude of strain were carried out. An Extreme Learning Machine (ELM) model optimized by Dragonfly Algorithm (DA) is proposed to predict the fatigue life of rubber based on measured rubber fatigue life data. Mean and amplitude of strain and measured rubber fatigue life were taken as input variables and output variables respectively in DA-ELM model. For comparison, genetic algorithm (GA) and particle swarm optimization (PSO) were used to optimize ELM parameters, and GA-ELM and PSO-ELM models were established. The comparison results show that DA-ELM model performs better in predicting the fatigue life of rubber with least dispersion. The coefficients of determination for the training set and test set are 99.47% and 99.12%, respectively. In addition, a life prediction model equivalent strain amplitude as damage parameter is introduced to further highlight the superiority of the DA-ELM model. The life

Lai, Wei, Wang, Yonggang, Zhen, Ran

A fatigue life prediction method of rubber material for Automobile vibration isolator under road load spectrum

2022-01-029103/29/2022

Automobile rubber isolator was subjected to random load cycle for a long time in the service process, and its main rubber material for vibration isolation was prone to fatigue failure. Since the traditional Miner damage theory overlooked the load randomness, it had a prediction error problem. In order to improve the prediction accuracy of rubber fatigue life, the traditional Miner damage theory was modified by random uncertainty theory to predict the rubber fatigue life under random load. Firstly, the rubber dumbbell-shaped test column, which was vulcanized from rubber materials commonly used in vibration isolators, was taken as the research object. The uniaxial fatigue test of rubber under different strain amplitudes and strain mean values was carried out. Then the fatigue characteristic curve of rubber with equivalent strain amplitude as the damage parameter was established. Secondly, the load spectrum of the rubber mount of an automobile powertrain was collected from different road

Zhu, Xijun

Improving Keyhole Stability During Laser Welding of AA5xxx Alloys

2022-01-028503/29/2022

Laser welding of the magnesium-bearing AA5xxx aluminum alloys is often beset by keyhole instability, especially in the lap through joint configuration. This phenomenon is characterized by periodic collapse of the keyhole leaving large voids in the weld zone. In addition, the top surface can exhibit undercut and roughness. In full penetration welds, keyhole instability can also produce a spikey root and severe top surface concavity. These discontinuities could prevent a weld from achieving engineering specification compliance, pose a craftsmanship concern, or reduce the strength and fatigue performance of the weld. In the case of a full penetration weld, the spikey root could compromise part fit-up and corrosion protection, or damage adjacent sheet metal, wiring, interior components, or trim. The objective of the present investigation was to evaluate the effect of travel speed on keyhole stability during laser welding of AA5xxx alloys without and with filler wire in lap through joint

Clarke, Jo Ann M., Hetrick, Elizabeth T.

Natural rubber life estimation through an extreme learning machine

2022-01-029703/29/2022

In engineering applications, rubber isolators are subjected to continuous alternating loads, resulting in fatigue failure. Although some theoretical models are used for the fatigue life estimation of rubber materials, they do not comprehensively consider the influences of multiple factors. In the present study, a model based on the extreme learning machine (ELM) is established to estimate fatigue life of natural rubber (NR) specimens. The mechanical load (engineering strain peak), ambient temperature (23℃, 60℃ and 90℃) and shore hardness (N45 and N50) of NR specimens are used as the input variables while the measure average fatigue life as the output variable of the ELM. The regression results and predicted life distribution of the established ELM model are encouraging. For comparison, the back propagation neural network (BPNN) model and the support vector machine (SVM) model are also implemented. It is concluded that the ELM model is superior to the other two ML models in accuracy and

Liu, Xiangnan

Fatigue Endurance Limit of Fasteners in Automotive Application

2022-01-028903/29/2022

Fastener commonly used in automotive industry plays an important role in the safety and reliability of the vehicle structural systems. In practical application, bolted joint would never undergo fully reversed loading, there always will be positive mean stress on bolt. The mean stress has little influence on the fatigue life if the maximum stress is lower than a threshold, which is the yield stress of the bolt. However, when the sum of the mean stress and the stress amplitude exceeds the yield stress, the endurance limit stress amplitude decreases fast as the mean stress increases. The purpose of this paper is to research fatigue endurance limit of fastener and establish the threshold for safe design in automotive application. In order to obtain the fatigue endurance limit at different mean stress levels, various mechanical tests were performed on M12x1.75 and M16x1.5 Class 10.9 fasteners using MTS test systems. Results show that the fatigue failure mode of bolts is different from that

Mao, Jianghui, Lin, Barry, Wu, Zhijun

Random Vibration Fatigue Evaluation of Plastic Components in Automotive Engines

2022-01-093903/29/2022

Light weighting in modern automotive powertrains call for use of plastics (PP, PA66GF35) for cam covers, intake manifolds and style covers, and noise encapsulation covers. Conventionally, in early stage of design these components are evaluated for static assembly loads & gasket compression loads at component level. However, engine dynamic excitations which are random in nature make it challenging to evaluate these components for required fatigue life. In this paper, robust methodology to evaluate the fatigue life of engine style cover assembly for random vibration excitations is presented. The investigation is carried out in a high power-density 4-cylinder in-line diesel engine. The engine style cover (with Polyurethane foam) is mounted on cam cover and the intake manifold using steel studs and rubber isolators to suppress the radiated noise. The style cover mounting ribs experience higher dynamic bending stresses due to the overhang of the mounting bosses from cam cover and intake

Soundarajan, Aravamuthan, Yadav, Vivek, K, Karthikeyan

The investigation of a contact and element-based approach for Cohesive zone modelling in the simulation of Delamination propagation

2022-01-029203/29/2022

The CAE industry always moves towards new ways to improve the productivity, efficiency and to reduce the solution times. Conventional method of Cohesive Zone Modelling has drawback of higher computation and modelling time. Due to this problem, sometimes Engineers need to avoid simulations and rely only on some sort of approximation of crack from previous designs. This approximation can lead to either product failure or overdesign of the product. A new approach is discussed in this paper to simulate crack initiation and propagation with Cohesive Zone Modelling. Conventional method uses Cohesive zone modelling with Hex or Penta elements by assigning material with cohesive properties, which increases computation and modelling time. The new approach models Cohesive zone as contact between two bodies, thus eliminating the need to use cohesive elements which will essentially reduce the computation time as well as modelling time. This approach uses Damage model method which allows modelling

Dhangar, Vinaykumar, Hosmath, Anjaney, Salunkhe, Prashant

Fatigue Life Prediction and Correlation of Engine Mount Elastomer Bush using A Crack Growth Approach

2022-01-092403/29/2022

Abstract: In passenger car, suspension link bushings, engine and transmission mount bushings and bump-stops are made of elastomer material, to maximize the durability and comfort. Thus, deformation behavior of rubber and its durability is important for product design and development. In virtual engineering, simulating rubber fatigue is a complex exercise, as it needs right modeling strategy and coupon testing based material data. Principal stretch based Ogden model is used to characterize the hyper elastic behavior of rubber. Fatigue crack growth approach used here for the fatigue analysis. Engine torque strut mount is used to control the engine and transmission fore aft motion and it is connected between body and Power Train (PT) system. Powertrain events are predominant for damage contribution of mount failure. So, it is important to predict fatigue life of mount elastomer bush. The objective of this work is to find the fatigue life of the elastomer bush for PT loads. Virtual

Elango, C., Pandi, Sathish Kumar, Mahadule, Roshan N, ZARRIN-GHALAMI, Touhid

Loading classification for fatigue design applied to automotive time-series

2022-01-029903/29/2022

This study focuses on variable amplitude loadings applied to automotive chassis parts experiencing carmaker’s specific proving grounds. They are measured with respect to time at the wheel centres and composed of the six forces and torques at each wheel, within the standard vehicle reference frame. In the scope of high cycle fatigue, the loadings considered are supposedly acting under the structure yield stress. Among the loadings encountered during the vehicle lifetime, two classes stand out: • Driven Road: loads measured during the vehicle manoeuvre (cornering, braking). • Random Road: random loads mainly coming from the road asperity. To separate both effects, a frequency decomposition method is proposed before applying any lifetime assessment methods. The usual rainflow counting method is applied to the Driven Road signal. These loadings, depending on the vehicle dynamic, are time-correlated. Thus, the load spectra is set only thanks to the vehicle accelerations time-measurement

Bellec, Enora, Doudard, Cédric, Facchinetti, Matteo, Calloch, Sylvain, Moyne, Sylvain

A comprehensive study on the effect of three different modeling techniques and pretension on fatigue life of bolts.

2021-28-018610/01/2021

For bolted joint design, the accuracy of decision made depends on several parameters like bolt pretension force used, 1D vs 3D bolt model, submodel vs full model and contact settings used for analysis. This paper discusses the effect of the above-mentioned parameters on bolts, thumb rules that can be used for designing and the parameters to be considered for decision making on the bolted joint design. The fatigue life of bolts subjected to all modelling techniques are calculated in this work and is used to compare between two different scenarios. All bolts are modelled with pretension. 3D bolts are modelled with surface to surface contact at the head and nut region. Among the 3d and 1d bolts, it was observed that the 3d bolts have a lesser change in pretension reaction force compared to 1d bolts. When the entire assembly model was compared to a sub-model including the bolts under consideration, it was found that both models have a close correlation with each other. Fatigue life of bolt

Ashik, Arshad Kalathil, Nimbalkar, Anant

MULTI-ENVIRONMENT ACCELERATED DURABILITY TEST FOR EXHAUST SYSTEM FLANGE JOINTS

2021-26-047209/22/2021

Accelerated testing is vital to meet stringent project timelines and is a key consideration for developing new testing methodology. Specifically, durability testing is one of the key fields of interest to deal with all aspects. Fatigue with exposure to multiple environments is a major cause of exhaust system flange joint failure. Physical verification of increased design life expectancy, demands longer testing time, while shorter time to market is main differentiator for competitiveness. Government policy induced timeline pressures added to the need of accelerated tests. The methodology described in this paper embraces these aspects to ensure a quicker flange joint testing, with due consideration to environmental impact. Until the BSVI norms, marginal leakage through the system joints was usual and acceptable. Stringent emission norms demand ‘near-zero’ leakage from exhaust systems. The system joints essentially being the most probable leakage zones, became the focus area

Dhumal, Sagar Prakash, Suryawanshi, Sachin, Mone, Manasi

Strength Evaluation and Validation of Structural Joints.

2021-26-031509/22/2021

Many methods have been developed to evaluate the fatigue life of structures when the its joints are as per ideal case. But if the joints are loosening, it leads to increase in loading on the other members which causes failures. Most commonly in commercial vehicle segment welding joint & Bolting joints are most popular ones. It is very easy to find out bolts strength & loosening effect in static conditions. But when vehicle is moving (i.e. dynamic condition), same method cannot be used. For this we have developed methodology to predict the bolts loosening in dynamic condition using vibration data. Similarly, loading may differ on the structural members if the welds are failing in dynamic conditions. To overcome this problem, in our organization we have a solution. Of course to simulate welding failures fatigue analysis is mandatory. We are using notch-stress approach for evaluating the welding strength of the joint. This method does not need weld material data instead it increases the

Desai, Ankit Desai, Telukala, Haricharan, Jadhav, Santosh, Kurna, Srinivas

A Case study on Effect of subsequent operations on shotpeened Crown Wheel Pinion (Hypoid Gear set) & Compressive Residual Stress analysis

2021-26-025209/22/2021

Abstract: The prime function of crown wheel pinion is to receive the power from Transmission & distribute to two-wheel Ends. Doing so these members will experience the tremendous Bending Fatigue. Shot peen is the one of the latest technologiesused to improve the bending Fatigue of the CWP. In this particular case- 6 CWP are taken for the Study to understand the effect of the operations after shot peen process. 3 Samples are named as Batch A, another 3 samples are named as Batch B. Both the batch CWP are shot peened. Then as a regular production Practice the Batch A CWP are process through Hard TurningAbrasive Lapping Hot Lubriting (Mn Phosphate)Fully Finish Ready for Assembly. Then Both the Batch A & batch B samples are taken for Residual Stress analysis using X-Ray Diffraction Technique. The measurement location is 50 microns below the surface. The results tabulated,found that Batch A samples shows decrease in Residual stress relatively to Batch B.This evident that post operations

Rao, Yathish

Component S/N Curve Testing Methodology for Exhaust System Validation

2021-26-045109/22/2021

The exhaust system design and development needs to be more flexible and easily adaptable for the dynamic changes with the introduction of new emission and noise regulations. Conventionally, bending moment testing is used to validate significant components like inlet and outlet pipe/cone joints and bend pipes through Bi-Ax test rig. Road load re-production test is an improvement of the conventional approach to predict component durability. However, it is more time consuming and involves the sequential process of acquiring road load data such as sensor instrumentation, strain measurement at the test track, data processing and input to Bi-Ax testing. S/N Curve testing is introduced recently as an alternate method to minimize the use of RLDA. It can be done upfront during vehicle unavailability and other challenging conditions and also as a parallel activity along with RLDA. Our objective is to show the simulation and validation process of Component S/N Curve testing with a LNT+DPF system

Rajadurai, Sivanandi, Natarajan, Suresh, Srivatsan, Rajesh, Sivalingam, Ananth

Thermo-Mechanical Fatigue and Press-Fit Loss Analysis Of Valve Seat Insert

2021-26-033809/22/2021

Valve seat inserts (VSI) are installed in cylinder heads to provide a seating surface for poppet valves. Insert material is more heat and wear resistant than the base cylinder head material and hence it makes them better suited for valve seating and improved engine durability. Also using inserts permits easier repair or rebuild of cylinder heads as only the wear surfaces need to be replaced. Desirable performance characteristics are appropriate sealing, heat-transfer and minimizing valve to VSI wear and undesired outputs include valve seat dropping and cracking. With downsizing trend of diesel engines, it leads to increasing power density and therefore higher cylinder pressure and temperatures. Hence the engine components are getting exposed to more severe loadings and hence to failure modes, which were not heretofore experienced based on the warranty data. Possible identified failure modes are insert’s yielding and corresponding press-fit loss leading to either it’s cracking or drop

Ozarde, Amit Prakash, McNay, Gene

Fatigue life of a rocker arm using Calibrated accelerated Life Test Approach

2021-26-045309/22/2021

Nagaraju Soma, Ranjith Sr, Pravin Kadekodi Center for Reliability Maintainability Safety, Eaton India Innovation Center, Pune, India somanagaraju@eaton.com Abstract Fatigue life estimation of mechanical components with a complex geometry is generally carried out using statistical methods. The commonly used approach in the industry is the staircase method using ISO12107. Staircase approach requires fifteen samples for exploratory testing to build the S-N Curve, eight of these being used to estimate the S-N curve in the finite fatigue life range (inclined line) and seven for the fatigue strength at the infinite life regime (horizontal line). In this paper staircase approach is compared with another approach to predict the fatigue life of an engine valve train ‘rocker arm’, calibrated accelerated life test (CALT) is discussed, which is very effective in predicting fatigue life, and reduce the test time significantly and quantifying reliability. The CALT test is performed with 3 samples at

Soma, Nagaraju, sr, Ranjith, Kadekodi, Pravin

Optimization of Scallop Design for Cylinder Head of a Multi-cylinder Diesel Engine for Reduction of Combustion Deck Temperatures and Simultaneously Enhancing Combustion Deck Fatigue Margin.

2021-01-123309/21/2021

Thermal fatigue crack failure is becoming the most important aspect in modern cylinder head design as modern engines are striving towards higher peak cylinder pressures. Thermal cracks are developed in the cylinder head due to varying operating conditions and thermal gradient generated because of operating conditions. The paper scope comprises an analytical and experimental study on the reduction of combustion deck temperature of a diesel engine through the introduction of scallop on the combustion face. There are methods such as cooling jacket optimization, faceplate insertion, scallops, and other measures to reduce the temperatures on the combustion deck. Among this Scallop, optimization is selected as a measure to make thermal fatigue crack-resistant cylinder head because changing cooling water jacket design will cause a change in castings for the cylinder head which may increase the development cost whereas introducing scallop will require just extra machining feature which does

Mahajan, Pratik, Bodake, Rajendra, Thakur, Anil

Wheels/Rims - Truck and Bus - Performance Requirements and Test Procedures for Radial and Cornering Fatigue

J267_202102-TEST-REC (Historical)02/04/2021

Truck and Bus Wheel Committee

Wheels/Rims - Truck and Bus - Performance Requirements and Test Procedures for Radial and Cornering Fatigue

J267_202102 (Current)

02/04/2021

Truck and Bus Wheel Committee

ARP5481A (Current)09/17/2020

This SAE Aerospace Recommended Practice (ARP) provides the recommended procedure for obtaining desired preloads in aircraft wheel tie bolts when mounting tires and assembling the wheel. It is generally referred to as the snug-angle bolted joint assembly procedure. It is also known as the “torque-turn” procedure in the heavy equipment ground vehicle industry.

A-5A Wheels, Brakes and Skid Controls Committee

Aftermarket Composite Wheels Made of Matrix Material and Fiber Reinforcement Intended for Normal Highway Use - Test Procedures and Performance Requirements

J3204_202009 (Current)

09/09/2020

This SAE Recommended Practice provides minimum performance requirements and uniform procedures for fatigue and impact testing, electrical resistance, and maximum operating temperature (MOT) of wheels intended for normal highway use on passenger cars, light trucks, and multipurpose vehicles.

Wheel Standards Committee