Computer Simulation of Weldment Fatigue Life
by
C. Y. Hou
N. Chen
Department of Civil Engineering
and
F. V. Lawrence
Department of Material Science and Engineering
Abstract
Modeling strategies for predicting the fatigue crack propagation life and total fatigue life of weldments are compared with experimental results reported in the literature. Three categories of analytical model are considered: (1) Models based solely on fatigue crack growth but which do not explicitly consider the effects of crack closure – Linear Elastic Fracture Mechanics or LEFM models; (2) Models based on fatigue crack growth but which do consider the effects of crack closure and the peculiar behavior of short cracks – the Crack Closure at a Notch model or CCN model; (3) Models which include fatigue crack initiation – Initiation-Propagation or IP models.
The results of this comparison suggest that both the CCN and IP give good predictions; whereas LEFM models which neglect crack initiation and the behavior of short cracks underestimate the total fatigue life particularly at long lives.
List of Symbols
a
Peterson’s constant
b
Fatigue strength exponent
C, C’, m
Paris law and modified Paris law material constants
c
Fatigue ductility exponent
e’f
Fatigue ductility coefficient
K’
Cyclic strength coefficient
n’
Cyclic strain hardening exponent
NI
Crack initiation life
NN
Crack nucleation life
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