Evaluation of random errors in Williams’ series coefficients obtained with digital image correlation

Abstract

The use of the Williams' series parameters for fracture analysis requires valid information about their error values. The aim of this investigation is the development of the method for estimation of the standard deviation of random errors of the Williams' series parameters, obtained from the measured components of the stress field. Also, the criteria for choosing the optimal number of terms in the truncated Williams' series for derivation of their parameters with minimal errors is proposed. The method was used for the evaluation of the Williams' parameters, obtained from the data, and measured by the digital image correlation technique for testing a threepoint bending specimen.

A Displacement Uncertainty Model for 2-D DIC Measurement Under Motion Blur Conditions

“…Digital image correlation is a broadly applied measurement technique in the field of experimental mechanics. The growth and diffusion of the aforementioned methodology is due to the relative ease to measure full field displacement and strain for both large-surface/large-scale deformation [9] and microstructure/nanoscale deformation [10], and, in general, DIC measurements are a valuable tool to solve complex problems in modeling the mechanical behavior of materials [11].…”

Digital photoelasticity for calculating coefficients of the Williams series expansion in plate with two collinear cracks under mixed mode loading

“…All the variety of fracture mechanics problems is therefore taken into account in the sole sequence of coefficients m k a .Terms with higher orders have been proven to be influential in some circumstances [9,10,16,[21][22][23][24][25][26][27][28][29][30][31][32][33][34]. In the present paper the experimental technique of photoelasticity was employed to investigate the effects of the higher order terms on both the shape and the size of the near crack tip isochromatic fringes for the wide range of specimens.…”