Accession Number : ADA112175

Title :   Crack Closure and Crack Growth Rate: An Empirical Model to Account for R.

Descriptive Note : Structures rept.,

Corporate Author : AERONAUTICAL RESEARCH LABS MELBOURNE (AUSTRALIA)

Personal Author(s) : Jost,G S ; Gratzer,L R

PDF Url : ADA112175

Report Date : Aug 1981

Pagination or Media Count : 37

Abstract : An empirical equation is proposed to account for stress ratio effects in fatigue crack growth based upon the crack closure concept. It is characterised by two fitted parameters. The new equation is used to establish effective stress intensity ranges for three sets of extensive crack growth rate data from the literature covering the stress ratio range -1 or = R 1. Least squares best fitted Paris equations are then used to predict crack growth lives fr comparison with the individual originals. Actual lives are almost invariably within the range from 1/3 to 2 times those predicted. The study shows that even better fits to the data would result from using a sigmoidal growth rate/effective stress intensity range relationship. This approach is being followed up.

Descriptors :   *Crack propagation, *Cracks, *Closures, *Rates, Models, Least squares method, Equations, Australia, Fatigue(Mechanics), Ratios, Stresses

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE