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Cyclic-inelastic deformation and fatigue resistance of notched-thin aluminum plates

An assessment of the accuracy and utility of the critical-location approach in fatigue-crack initiation analysis at notch roots

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Abstract

The results of experiments designed to develop data to assess the accuracy and utility of the critical location concept in applications of fatigue-crack nucleation analysis at notch roots are presented and discussed. Fully reversed and nonzero mean-stress data are presented over a range of lives which encompass both elastic and inelastic deformations for thin-notched specimens and smooth specimens made of 2024 T351 aluminum-alloy sheet. Notch-root strains were measured via an extensometer, whereas the formation of small cracks was detected via an eddy-current transducer. Data reported indicated the validity of the assumption that smooth and notched specimens form cracks at the same cycle number when identical deformation histories are imposed at their respective critical locations. They also serve to demonstrate the accuracy and utility of the critical-location approach in analysis to predict the formation of small cracks at notches in coupons and components.

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Abbreviations

E :

elastic modulus

i,p,f :

as subscripts designate initiation, propagation and fracture values

K f :

fatigue-notch factor

K t :

theoretical-stress-concentration factor

ℓ:

crack length

mx, mn :

as subscripts designate maximum and minimum values

N,R=2N, R f :

cycles, reversals and reversals to failure

R :

algebraic ratio of minimum to maximum stress

s,e :

stress, strain in a smooth specimen, respectively

S, e n :

nominal stress, nominal strain in notched plates, respectively

t,e,p :

as superscripts designate total, elastic and plastic components

σ,ε:

stres strain at a notch root, respectively

Δ:

peak to peak value of the corresponding quantity

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Authors and Affiliations

  1. Battelle's Columbus Laboratories, 43201, Columbus, OH

    B. N. Leis (Senior Scientist) & N. D. Frey (Senior Technician)

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  1. B. N. Leis
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  2. N. D. Frey
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Leis, B.N., Frey, N.D. Cyclic-inelastic deformation and fatigue resistance of notched-thin aluminum plates. Experimental Mechanics 22, 287–295 (1982). https://doi.org/10.1007/BF02327246

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  • DOI: https://doi.org/10.1007/BF02327246

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