ISSN: 1945-7553
Page Count: 7

Effect of Loading Parameters on Post-Overload Fatigue Crack Closure

Verma, BB
R. E. College,

Pandey, RK
I.I.T. Delhi, New Delhi,

Chinnadurai, R
Technical Centre, Civil Aviation Department, New Delhi,

(Received 14 July 1997; accepted 21 May 1998)

Abstract

The tensile overload cycle has a significant effect on fatigue behavior, resulting in an enhanced crack closure level and reduced fatigue crack growth rate. The present investigation studies the effect of opening mode tensile overload on crack closure in 2024-T3 aluminum alloy and 4130 Cr-Mo steel sheets. It is found that the overload-induced closure parameter KopOLincreases with basic stress intensity range ΔK and overload level. The result further indicates that the significant closure effect can be obtained only beyond a limiting level of overloading ratio (OLR)=1.30 in both the alloys, where OLR is the ratio of the maximum stress-intensity factor in the overloading cycle to the maximum stress-intensity factor in the constant-amplitude loading cycle.

Keywords:
overloading cycle, crack closure, plastic zone size, compressive residual stress, crack growth retardation

Paper ID: JTE12159J
DOI: 10.1520/JTE12159J
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