| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 92 === The objective of this work is to develop an enriched element-free Galerkin method for the analysis of three-dimensional fracture problems. By this method, the displacement fields which account for the stress singularity behaviors nearby the crack front and the boundary layer effect at the intersection point between the crack front and the free surface of the structure are embedded to enrich the trial functions. The three-dimensional stress intensity factors are thus treated as unknown parameters and can be calculated with the nodal displacement fields directly. To estimate the accuracy of the method developed, this work analyzes several representative three-dimensional fracture problems, including the single edge and slanted edge through-thickness cracks, embedded elliptical and semi-elliptical cracks, and quarter-elliptical corner crack etc. The influence of crack sizes on the three-dimensional stress intensity factors is also studied. Excellent agreements between the calculated results and available references demonstrate the high accuracy and applicability of the enriched element-free Galerkin method developed on the analysis of three-dimensional fracture problems.
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