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Structural Optimization based on Fatigue Analysis Results for increase in the payload capacity

VE Commercial Vehicles Ltd-Srinivas Kurna
VE Commercial Vehicles, Ltd.-Nikhil Soman
  • Technical Paper
  • 2019-28-2574
To be published on 2019-11-21 by SAE International in United States
In commercial Vehicles industry, customer demands the vehicle with higher payload capacity. In order to achieve the higher payload, the vehicle weight must be reduced. Role of CAE (Computer Aided Engineering) team in the above objective is to provide optimized solution for the currently available designs. There are many capable softwares available in the market for the optimization. But performing optimization on the basis of static or dynamic analysis involves a little risk of design losing the strength. In our organization, we have developed a method, which will eliminate the risk of lower strength of the component. In this method, modified design from the optimization analysis has to undergo the fatigue analysis repetitively until it qualifies both the criteria of optimized design & adequate fatigue strength. In the above process fatigue analysis is time consuming process. To reduce the time taken by fatigue analysis, we are using the frequency based vibration fatigue method. Hence, providing ease of iterations in the overall optimization process. We are using above method in our regular practice. In this paper,…
 

STATISTICAL ANALYSIS OF LOW CYCLE FATIGUE PROPERTIES IN METALS FOR ROBUST DESIGN

GM Global Technical Center, USA-Abolhassan Khosrovaneh
General Motors Technical Center India-Karthigan Ganesan, Biswajit Tripathy
  • Technical Paper
  • 2019-28-2576
To be published on 2019-11-21 by SAE International in United States
Objective: In ground vehicle industry, strain life approach is commonly used for predicting fatigue life. This approach requires use of fatigue material properties such as fatigue strength coefficient (σf'), fatigue strength exponent (b), fatigue ductility coefficient (εf'), fatigue ductility exponent (c), cyclic strength coefficient (K′) and cyclic strain hardening exponent (n′). These properties are obtained from stable hysteresis loop of constant amplitude strain-controlled uniaxial fatigue tests. Usually fatigue material properties represent 50th percentile experimental data and doesn't account possible material variation in the fatigue life calculation. However, for robust design of vehicle components, variation in material properties need to be taken into account. In this paper, methodology to develop 5th percentile (B5), 10th percentile (B10) and 20th percentile (B20) fatigue material properties are discussed. Possible material variation in fatigue life prediction is included as B5, B10 and B20 fatigue material properties. Methodology: Fatigue strength coefficient (σf') and fatigue strength exponent (b) are obtained by performing a linear regression on true stress amplitude (∆σ/2) versus reversals to failure (2Nf) in log-log scale. Fatigue ductility coefficient (εf')…
 

Determine Thermal Fatigue Requirements for PEPS Antenna Copper Wire over Vehicle Lifetime with defined Reliability Requirements.

GMTCI-Abhinav Jauhri
  • Technical Paper
  • 2019-28-2582
To be published on 2019-11-21 by SAE International in United States
Reliability states the degree to which the result of a measurement, calculation, or specification can be depended on to be accurate. And, tests according to GMW specifications represents a minimum of 15 years of vehicle life time with defined Reliability and Confidence level. In this work, actual number of thermal cycles for Thermal Fatigue tests (Thermal Shock and Power Temperature Cycle) are calculated for Copper Wire whose Coffin Manson exponent is 5. Overstressing the PEPS Antenna under thermal fatigue requirement (defined number of thermal cycles based on Reliability and Confidence requirements) will lead to broken Copper wire which will result in component’s functional failure and thus impossible to continue reliability testing. The objective of this paper is to determine thermal fatigue requirements for Antenna’s Copper wire whose Coffin Manson exponent is 5. Testing with exact number of thermal cycles will reduce the validation failures owing to broken Copper wire and thus save incurred revalidation cost. The current study is limited to only adjusting the thermal fatigue requirements (Number of Thermal Cycles) for only specific E/E…
 

A novel method of Improving Ride Comfort of Two Wheeler by Optimization of Seat Parameters.

Carmel Polytechnic College-Francis Augustine Joseph
Saingits College of Engineering-Arun Kottayil Varghese
  • Technical Paper
  • 2019-28-0013
To be published on 2019-10-11 by SAE International in United States
Two-wheeler plays a significant role in personal transportation in India. People prefer two-wheelers, which has better fuel economy, comfort, and performance. It is vital to enhance comfort, as the seat is in direct contact with the user. Better user comfort improves the vehicle feel and behavior. Dynamic comfort analysis is necessary to understand and improve the vibration characteristics of the human-seat system. The vibration characteristics under analysis are Natural frequency, Maximum transmissibility, Attenuation frequency, and Transmissibility at 6 Hz. A test set-up was developed to collect data samples with different seat characteristics. The data collected from the seat are IFD, Hysteresis, Air-Permeability, Resilience, Thickness, and Mass. The relation between the seat parameters and vibration characteristic is established by statistically analyzing the data. Best seat was identified by ranking vibrational characteristics. Correlation analysis determines the best seat by subjective rating of the sample and seat vibration ranking. Keywords: Transmissibility, two-wheeler seat, Polyurethane foam, Comfort and fatigue, correlations, ride comfort, Vibration Isolation,Optimization.
 

Design Analysis & Development of High speed Rotating Fatigue test with integrated by twisting test.

Avinash Prakash Barve, Rahul Jangam, Adm Aman Soni, Pravin Pandagre, Hardik Bhautkar, Bhushan Chapke, Shantanu Bankar, Faisal Hussain, Adm Paresh Setiya
  • Technical Paper
  • 2019-28-0053
To be published on 2019-10-11 by SAE International in United States
Testing different materials for their fatigue behaviour has been a primary requirement before consider the material for use in any environment with continuous fluctuating load. There has been considerable evolution in the design of fatigue testing machines for over a century now. . In the present paper is shown a testing machine is designed and developed in such a way as to be proficient of exerting simultaneous cyclic twisting moments, such moments being uniformly distributed along the entire pawn length of the test specimen. The ratio of twisting moments can be adjusted within the range 0 to 0.5, the angular deflection of the specimen being reserved in the machine. The fatigue testing machine mostly used for industrial or a laboratory use, which are limited to performing single fatigue tests with leading cost. This paper elaborates the experimental setup of the traditional fatigue testing machine is an integrated with twisting test, to experimentally study the effect of fluctuating stresses on the material. The significance of the machine is its cheap overall price is the most important…
 

Systematic work flow for fatigue life prediction of Automotive components

Mahindra & Mahindra, Ltd.-Nitin Kumar Khanna, Baskar Anthonysamy, Krishna Shettipally, Manohar Kalal
  • Technical Paper
  • 2019-28-0021
To be published on 2019-10-11 by SAE International in United States
Fatigue life estimation of automotive components is a critical requirement for product design and development. Automotive companies are under tremendous pressure to launch new vehicles within short duration because of customer’s changing preferences. There is a necessity to have a comprehensive virtual simulation and robust validation process to evaluate durability of vehicle as per customer usage. Test track and field test, are two of the most time-consuming activities, so there is a need of simulation process to substitute these requirements. This paper summarizes the overall process of Accelerated Durability Test with measured road loads. Based on category of vehicle, type road profiles and the customer usage pattern, the wheel forces, strains and acceleration are measured which is used to derive the equivalent duty cycles on proving ground. The wheel force transducers (WFT) are used to derive loads for fatigue life estimation. A full vehicle model is prepared in ADAMS CAR and validated through Physical testing. The loads on suspension hard points extracted from the validated MBD model. These loads at various hard-point locations, are used…
 

Critical wear assessment of AA8011/Hybrid metal matrix composites with surface amendment using Friction Stir process

Sri Krishna College of Engg. and Tech.-Soundararajan Ranganathan, Shri Vignesh Ramachandran, Ramprakash Palanivelu, Saravanakumar Ramasamy
  • Technical Paper
  • 2019-28-0096
To be published on 2019-10-11 by SAE International in United States
Friction Stir Process (FSP) was used for surface modification of steel, titanium, aluminum and magnesium based alloy has been considerably reviewed during the last decade. FSP can improve surface properties such as abrasion resistance, hardness, strength, ductility, corrosion resistance, fatigue life and formability without affecting the bulk properties of the material. The aluminum alloy having low ductility and softness characteristics are restricted because of their poor tribological properties. Preliminary studies reveal that, an ideal circumstance is to improve the aluminum alloy material life cycles by the way of strengthening the surface layer which can be modified through reinforcing nano particles through FSP. By the way, this experiment was carried out to obtain three set of samples like virgin AA8011, AA8011 with shape memory alloy and AA8011 along with shape memory alloy and silicon nitride during FSP under optimal process parametric condition. The improved distributions of nanoparticles were obtained after each FSP pass and progress in mechanical properties was observed. On the other hand to assess the tribological performance of prepared hard surface, three samples were…
 

Tensile and Fatigue behavior of shallow cryogenically treated En19 alloy steel

BSACIST-Loganathan Sekar, Tamil Arasan
SRM Institute of Science and Technology-Rajendran Raj
  • Technical Paper
  • 2019-28-0100
To be published on 2019-10-11 by SAE International in United States
Wear, tensile and axial fatigue tests were conducted on shallow cryogenically treated En19 medium carbon alloy steel to investigate its mechanical behavior. The test samples are conventionally heat treated then oil quenched at 34 ˚C. Followed by the samples were kept under shallow cryogenic treatment to -80˚C for 12 hours using liquid nitrogen. Then the samples were tempered in a muffle furnace to relieve the induced residual stresses. Wear, Tensile and axial fatigue test was carried out on both treated and non-treated samples to measure its wear resistance, tensile strength and fatigue behavior respectively. Microscopic examination also done using scanning electron microscope to compare the effect of shallow cryogenic treatment on its microstructure. The results exposed that there is a reduction in the tensile strength and fatigue life of shallow cryogenically treated samples over base metal and improved wear resistance.
 

Influence of Retained austenite on fatigue performance of carburized gears

Comstar Automotive Tech P Ltd.-Rajeshkumar Ramasamy, Seenuvas Sivathanu, Varatharaj Neelakandan, Thulasirajan Ganesan, Praveen Chakrapani Rao
  • Technical Paper
  • 2019-28-0102
To be published on 2019-10-11 by SAE International in United States
SAE 8620 and 20MnCr5 are widely used materials for gears in automotive application. The materials were subjected to carburizing process to obtain the identical hardened layer of HRC 61-64. The carburized surface and core properties of the materials were examined and characterized through optical microstructure to measure the presence of cementite carbides and Retained Austenite (RA). From the results, it was found that the SAE 8620 and 20MnCr5 materials have 10 % and 14% of RA respectively. Whereas, the core and case structure were free from network carbides. The fatigue test were conducted to correlate the RA and fatigue strength of the materials. It was revealed that material with lower RA has higher fatigue strength than material with higher RA. Higher the amount of retained austenite leads to reduction in amount of martensitic and compressive residual stress attributed to lower the contact fatigue strength. Untransformed austenite is metastable and it is transformed to untempered martensite, which causes brittleness to the component and leads to premature failure.
 

Torsional Stiffness Analysis Of Tubular Space-frame Chassis

SRM Institute of Science and Technology-Venkata Naga Bhavani Prasad Sodisetty, Anurag Pandey, Devansh Balachandran Iyer, Navneet Kumar
  • Technical Paper
  • 2019-28-0033
To be published on 2019-10-11 by SAE International in United States
Torsional Stiffness is required in an automotive when there is a lateral load transfer as it happens during turning. It also occurs when there is bump on one side of a chassis while droop on the other. A torsionally stiff chassis would provide better stability and uniform load transfer in an automotive. The lateral members in a chassis play a crucial role in increasing the torsional stiffness but they result in increased weight. The relation between mass and structural stiffness of a chassis is crucial to optimize the dynamics of an automotive. The current trends in research aim at increasing the torsional stiffness and optimizing mass for the same and thus increasing the stiffness to mass ratio. This is validated with the help of various FEA softwares. The different cases involved in real world scenario are simulated and then the stiffness is optimized accordingly. This FEA analysis is further validated using experimental analysis. An experimental jig is fabricated and setup for every condition. Static conditions are used for both FEA and experimental analysis. A list…