Experimental evaluation of stress field around the sharp notches using photoelasticity

摘要

A higher order representation of the stress field around the sharp notch has been utilized for calculating notch stress intensity factors (NSIFs) as well as the coefficients of higher order terms by the technique of photoelasticity. Adding the higher order terms to the singular term makes it possible to collect the data points from a larger zone, which helps to simplify the data collection from experiments. Moreover, the effects of higher order terms in the region near the notch tip are taken into account. To utilize the advantages of whole-field photoelasticity and minimize the experimental errors, a large number of data points have been employed and the overdeterministic least squares method combined with the Newton-Raphson method have been used to solve the resulting system of nonlinear equations. The NSIFs for a laboratory specimen called V-notched Brazilian disk (V-BD) were calculated for various notch angles under pure mode I, pure mode II and mixed mode I/II loading conditions. In addition to NSIFs, the coefficient of the first non-singular term of 30° notch was calculated experimentally and the effects of this term on the stress distribution in the vicinity of notch tip were investigated. A good correlation was observed between the experimental results and the numerical results obtained from finite element analysis.