Finite Element Based Fatigue Calculations

N. Bishop¹ and F. Sherratt^2
1RLD Ltd, Hutton Roof, Eglinton Road, Tilford, Farnham, Surrey, GU10 2DH
²Engineering Consultant, 21 The Crescent, Brinlow, Nr Rugby, Warwickshire, CV23 OLG

https://doi.org/10.59972/ta5h05jd

HT17, January 2000

ISBN (Online): 978-1-83979-008-9

ISBN (Hardcopy): 978-1-910643-65-5

Preface

Fatigue analysis procedures for the design of modern structures rely on techniques, which have been developed over the last 100 years or so.

Initially these techniques were relatively simple procedures, which compared measured constant amplitude stresses (from prototype tests) with material data from test coupons. These techniques have become progressively more sophisticated with the introduction of strain based techniques to deal with local plasticity effects. Nowadays, variable amplitude stress responses can be dealt with.

Furthermore, techniques exist to predict how fast a crack will grow through a component, instead of the more limited capability to simply predict the time to failure. Even more recently techniques have been introduced to deal with the occurrence of stresses I more than one principal direction (multi-axial fatigue) and to deal with vibrating structures where responses are predicted as PSDs (Power Spectral Densities) of stress.

Today, 95% of all fatigue design calculations are covered by one of three approaches, i.e., Stress-Life or Crack-Propagation. Furthermore, since stress or strain are governing variables it has been usual to test prototype components in order to obtain the required data needed for the fatigue analysis.

However, with the introduction of Finite Element Analysis (FEA) techniques, has come the possibility of doing fatigue calculations long before a prototype exists. Furthermore, a dramatic improvement in computing power has made FE based fatigue life calculations a routine task. FE has been around for some time and is now a mature technology. The purpose of this book is to provide an introduction to the basic underlying concepts of fatigue analysis within the FE environment.

This goal can be stated further as to give engineers involved in Finite Element a basic understanding of fatigue; and to give engineers involved in fatigue a basic understanding of Finite Element. A number of examples are used throughout the text to illustrate the concepts and potential applications.

Contents

References

General References - FEA

The best source of practical information concerning FE analysis is either one of the many NAFEMS publications on the topic, or one of the proprietary FE analysis software vendor product reference texts, such as the MSC.Nastran or MSC.Patran user manuals.

General References - Fatigue

J Bannantine, Fundamentals of Metal Fatigue Analysis, Prentice Hall, 1990.

GE Dieter, Mechanical Metallurgy, Third Edition, McGraw-Hill Book Company, New York, 1986.

MSC.Fatigue Version 8 Quick Start Guide, MSC Software Corportation, Redhill Drive, Costa Mesa, California. 1998.

MSC.Fatigue Version 8 User Manual, MSC Software Corportation, Redhill Drive, Costa Mesa, California. 1998.

The Stress-Life (S-N) Approach)

RC Juvinall, Engineering Considerations of Stress, Strain and Strength, McGraw Hill, New York, 1967.

CC Osgood, Fatigue Design, 2^nd ed, Pergamon Press, Oxford, 1982.

HO Fuchs and RI Stephens, Metal Fatigue in Engineering, Wiley-Interscience, New York, 1980.

RE Peterson, Stress Concentration Factors, John Wiley and Sons, New York, 1974.

VB Koettgen, R Olivier and T Seeger, Fatigue Analysis of Welded Connections Based on Local Stresses, International Institute of Welding, (1992), document IIW XIII-1408-91.

The Strain-Life (ε-N) Approach

American Society for Testing and Materials, Manual on Low Cycle Fatigue Testing, ASTM STP 465, ASTM, Philadelphia, 1969.

American Society for Testing and Materials, Annual Book of ASTM Standards, ASTM Standard E606-80, ASTM, Philadelphia, 1980.

JA Graham (ed), SAE Fatigue Design Handbook, Vol 4, Society of Automotive Engineers, Warrandale, Pa 1968.

Crack Propagation Analysis Using LEFM

A General Introduction to Fracture Mechanics, J. of Strain Analysis, Vol. 10, No 4, October 1975, I.Mech.E, London.

Broek, D, Elementary Engineering Fracture Mechanics, Martinus Nijhoff, The Hague, 1982.

Rooke, D.P. and Cartwright, D.J. A Compendium of Stress Intensity Factors, Her Majesty's Stationery Office, 1976.

Multi-axial Fatigue Analysis

JA Bannantin, and D.F. Socie, Observations of Cracking Behaviour in Tension and Torsion Low Cycle Fatigue, in "Low Cycle Fatigue", ASTM STP 942, American Society for Testing and Materials, Philadelphia, 1988.

YS Garud, Multiaxial Fatigue, A Survey of the State of the Art, J Test. Eval., Vol 9, No 3, 1981, pp 165-178.

Vibration Fatigue Analysis

N. W. M. Bishop, Vibration Fatigue Analysis in the Finite Element Environment Invited Paper presented to the XVI Enuentro Del Grupo Espanol De Fractura, Torremolinos, Spain, 14-16 April 1999.

N. W. M. Bishop and F. Sherratt, A Theoretical Solution for the Estimation of Rainflow Ranges from Power Spectral Density Data. Fat. Fract. Engn. Mater. Struct., 13, 311-326, 1990.

N. W. M. Bishop and F. Sherratt, Fatigue Life Prediction From Power Spectral Density Data, Part 1: traditional approaches. Environmental Engineering, 2, No. 1, pp11-14, March 1989. Part 2: Recent developments, ibid No 2, pp5-10, June 1989.

ME Bowitz and A Caserio, Solder Joint Reliability in Patriot Advanced Capability Missile Electronic Components Using MSC.Fatigue, special paper published at MSC Aerospace User Conference, California, 1999.

SO Rice, Mathematical analysis of random noise. Selected papers on noise and stochastic processes, Dover, New York, 1954.

JS Bendat, Probability functions for random responses. NASA report on contract NAS-5-4590, 1964.

T Dirlik, Application of Computers in Fatigue Analysis, University of Warwick Thesis, 1985.

F. Sherratt, Current applications of frequency domain fatigue life estimation, Environmental Engineering, Vol. 9, 4, pp 12-21, December 1996.

Cite this book

N. Bishop, F. Sherratt, Finite Element Based Fatigue Calculations, HT17, NAFEMS, 2000, https://doi.org/10.59972/ta5h05jd