Abstract
The goal of this research was to develop a method to represent and analyze the stress field surrounding two edge cracks located in a finite body. The generalized Westergaard equations were utilized to represent the independent stress fields created by the presence of each crack tip. The Schwarz alternating method was then employed to satisfy traction free boundary conditions on each of the two pairs of crack faces which were violated by a simple superposition of the two independent crack tip stress fields. This combined Westergaard-Schwarz approach was combined with local collocation and used to analyze the case of two parallel edge cracks located in a remote bending field. Photoelastic experiments were analyzed to establish the validity of the combined Westergaard-Schwarz approach and the results were convincing. Numerical experiments (finite-element models) were analyzed in which the length of one crack was assumed to be fixed while the length of the second crack and the distance between the two cracks were varied. Results were verified by comparing finite-element obtained J-integrals with those calculated with the analysis results. The results obtained were used to study how the crack separation between the two cracks and the ratio of the crack lengths affected the stress intensity factors for each crack. The results showed that the crack length ratio affected the calculated opening mode stress intensity factors significantly, especially for the crack that was shorter. For the cases considered, it was also found that changing the separation distance had little effect on the opening mode stress intensity factors while shear mode stress intensity factors at each crack tip decreased steadily as this distance was increased.
Hardin, Patrick Wayne (1993). The stress field around two parallel edge cracks in a finite body. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1993 -THESIS -H262.