Abstract
There were two objectives in this research: to develop a high density film grating (80 lines/mm) suitable for use in geometric moire experiments and to develop an algorithm which could be used to determine the fracture parameters, such as the stress intensity factor, associated with a crack-tip displacement field due to mixed mode loading. The algorithm developed combines a series representation of the crack-tip displacement equations with the method of local collocation to calculate the fracture parameters. The algorithm can also account for the presence of rigid body rotation and translation which are often present in experimental moire patterns. Finite element modeling, numerical experiments, and geometric moire tests were used to test the validity of the algorithm. Each evaluation method included both opening and mixed mode loading, with and without rigid body rotation. The 80 line/mm film gratings were successfully used for the geometric moire experiments, which were conducted on both P and aluminum. The analyses of the finite element models indicated that the algorithm developed could be used to determine the opening and shear mode fracture parameters, without being affected by the rigid body rotation. The numerical experiments demonstrated that the determination of the fracture parameters was influenced by the accuracy of the input data. The geometric moire experiments, using 80 line/mm gratings, demonstrated that the algorithm could be used successfully to determine the opening mode stress intensity factor with reasonable accuracy. The ability to determine the shear mode stress intensity factor with sufficient accuracy using geometric moire was not conclusively demonstrated.
Kmiec, Kenneth James (1994). Determination of the fracture parameters associated with mixed mode displacement fields and applications of high density geometric moire. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -K66.