Strain gage radial locations for the accurate determination of mode I stress intensity factors

摘要

Strain gage based methods for experimental determination of stress intensity factors (SIFs) are equally powerful as compared to the other methods such as photoelasticity and caustics.However,a major problem with the strain gage methods is the lack of practical recommendations for appropriate radial locations for strain gages for accurate measurement of SIFs.Determination of valid gage locations is thus an open problem.In order to obviate this important problem,a finite element based approach has been suggested in the present investigation for determination of valid or optimal strain gage locations for determination of the mode I SIFs.The proposed approaches are strongly supported by the theory.The present work attempts to estimate the maximum permissible radial distance max r for strain gages (from the crack tip) using the proposed finite element based approaches.This max r of a configuration in turn can be used to obtain the valid locations for strain gages for accurate determination of mode I SIFs.The results of the present investigation show that very accurate values of max r can be obtained using the proposed approach.Dependence of max r on crack length to width ratio has also been investigated in the present work.