STRAIN-ENERGY RELEASE RATES OF MODIFIED ENF SPECIMEN FOR MIXED-MODE FRACTURE

A modified ENF specimen for the mixed-mode fracture test is analyzed by the finite element method. The analysis is performed to calculate the mode I and mode II strain energy release rates and to compare the results with those obtained by the simple beam theory. The virtual crack closure method and displacement extrapolation method are employed in the finite element analysis to calculate the strain energy release rates. As for the relation between G(I)/G(T) and the thickness ratio for the modified ENF specimen, the finite element result shows some discrepancy with the result by the simple beam theory. The results of present analysis show that the mode partitioning by the simple beam theory does not hold good for the specimen with different thicknesses of upper and lower arms.