Multiaxial fatigue: An overview and some approximation models for life estimation

This paper presents a methodology for analyzing the multiaxial loads acting on a steering knuckle under operating conditions. The knuckle is a critical structural part which connects the wheel in a car to the steering and suspension system. Computeraided modeling and analysis were carried out on the knuckle, and the results were compared for conventional and metal matrix composites (MMC) with ANSYS software. The simulation showed that the steering-arm region failed under cyclic load conditions. Accordingly, the knuckle was optimized with a genetic algorithm and a modified design was proposed. Steering knuckles were fabricated from three different materials: ductile iron, LM 6 alloy and MMC with a modified design were experimentally tested in the steering-arm region to evaluate the fatigue life. Simulation results showed that the fatigue life of the MMC knuckle was 1.946E+06 fatigue cycles after optimization whereas experimental results showed 1.20E+06 cycles. Knuckle weight reduction of 60% was achieved by replacing ductile iron with MMC. Hence it is recommended to use MMC steering knuckles in automobiles.

Section: Experimental Fatigue Resultscontrasting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Fatigue Life Analysis and Optimization of a Passenger Car Steering Knuckle Under Operating Conditions

Sivananth¹,

Vijayarangan²

2015

“…Numerous research efforts have been made to safely assess the fatigue life of mechanical components under time-variable loadings [3][4][5]. Fatigue life prediction in real components is a complex process having a number of variables to deal with to avoid unwanted and critical failures [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Even under uniaxial loads, multiaxial stresses often exist, although typically in-phase, due to geometric constraints at notches. Such multiaxial loads and stress states are frequently encountered in many industries, including automotive, aerospace, and power generation, among others [5,17,24]. Research to develop new fatigue estimation models is continuously underway, but a general purpose model has still not been developed for the wide-ranging description of fatigue phenomena [4,[25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Fatigue life prediction of titanium alloy for block loading using the hybrid approach of critical plane and continuum damage mechanics

Rahman¹,

Kamal²

2017

The present study is related to the performance analysis of the newly proposed fatigue estimation model for titanium alloy BT9 against block loading. Lately, research efforts have been concentrated on developing the capability to handle complex multiaxial loading conditions for fatigue estimation. The current study is focused on testing the proposed hybrid approach involving the critical plane and continuum damage mechanics. The calibration of the proposed model is done by determining the model coefficients by using a genetic algorithm. Experimental fatigue lives for titanium alloy BT9 with block loading consisting of axial, torsion and out-of-phase axial-torsion loading segments are considered to analyse the accuracy of the proposed model. The proposed model is validated by using finite element analysis to estimate fatigue life for titanium alloy BT9. Simplifications were assumed to handle the block loads, and axial, torsion and out-ofphase loading conditions were used for calibration. The estimated fatigue life results show good agreement with published results for block loads.

“…Even under uniaxial loads, multiaxial stresses often exist, although typically in-phase, due to geometric constraints at notches. Such multiaxial loads and stress states are frequently encountered in many industries, including automotive, aerospace, and power generation, among others [15][16][17]. Many scientific centers and researchers are dealing with this issue, making new tests and developing models for description of the fatigue phenomena.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Life Estimation Based on Continuum Mechanics Theory With Application of Genetic Algorithm

Kamal¹,

Rahman²

2015

In recent years research on fatigue estimation methods has focused on developing the capability to handle complex multiaxial loading conditions. The present study presents the development of a new fatigue life estimation model using the concepts of continuum mechanics with a critical plane based approach, where a genetic algorithm is used to estimate the coefficients of the model. Experimental fatigue lives for steel alloy C40 for in-phase and out-of-phase loading conditions are used to calibrate and analyze the accuracy of the proposed model. Finite element analysis is used to determine the experimental fatigue life of steel alloy C40 published in literature for validation purposes. The proposed model is simple to apply as it does not need to determine any new material constants or properties for the new model. Fatigue life prediction from the proposed model shows good agreement with experimental results for in-phase and outof-phase multiaxial loading.