Experimental determination of strain-fatigue life curve is expensive considering the time and effort involved. Several empirical relations based on monotonic tensile properties and/or hardness is available for estimating strain-fatigue life properties. Existing criteria to evaluate the accuracy of these empirical relations are limited by the data points in the strain-fatigue life curve. A new criterion based on the prediction errors of fatigue constants is proposed to overcome the limitation. Around eight prediction methods are evaluated for two hundred twenty-six steel grades from literature using the existing and the proposed criteria. It is observed that the conclusions from the new criterion are more reliable than the existing criteria. © 2010 Elsevier Ltd. All rights reserved.

K Hariharan

Department of Mechanical Engineering

Raghu V. Prakash

M. Sathya Prasad

DATA POINTS

Empirical relations

ERROR CRITERION

Experimental determination

Fatigue life

FATIGUE LIFE CURVE

Fatigue life prediction

LEAST SQUARE FITS

PREDICTION ERRORS

Prediction methods

SCATTER BAND

STEEL GRADES

WEIGHTED ERROR CRITERION

Forecasting

Rating

Fatigue of materials

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

International Journal of Fatigue

The fatigue behaviour of cold rolled and annealed sheet metals are influenced by the anisotropy of mechanical properties due to crystallographic texture. However, the existing fatigue strain-life models are primarily meant for isotropic material behaviour. In the present work, the Coffin-Manson equation for strain-life is modified to include the effect of anisotropy using phenomenological plasticity models. It is observed that the variation of strain hardening exponent is critical to model the strain-life behaviour. Variation of strain hardening exponent with orientation is modelled using existing anisotropic yield criteria. The prediction of fatigue life using the proposed model correlates well with the experimental results of Al6061-T6 along different orientations. The proposed model can be used to predict the fatigue properties along any orientation from the fatigue data along one orientation and monotonic mechanical properties along longitudinal, transverse and diagonal directions. © 2012 Blackwell Publishing Ltd.

Fatigue and Fracture of Engineering Materials and Structures

Modification of fatigue strain-life equation for sheet metals considering anisotropy due to crystallographic texture

Room temperature low cycle fatigue (LCF) and fracture behaviour of a medium carbon V-bearing microalloyed steel has been studied. The experimentally determined LCF life is compared with the life predicted by the 'modified universal slopes' equation. Cyclic stress response showed softening at lower plastic strain amplitudes (≤0.3%) and hardening at higher plastic strain amplitudes (>0.3%). The possible reasons for the above behaviour are discussed. An analysis of the fracture surfaces revealed a mixed mode of fracture that involved different fracture mechanisms. Cracks did not initiate at the inclusions. Copyright © 1997 Elsevier Science Ltd. All rights reserved.

Low cycle fatigue behaviour of a medium carbon microalloyed steel

Structural and Multidisciplinary Optimization

Parametric structural optimization with respect to the multiaxial high-cycle fatigue criterion

Journal	International Journal of Fatigue
ISSN	01421123
Open Access	No