FEM Analysis On Dynamic J-integral Under The Influence Of The Specimen Sizes.

Because of the complexity to itself on dynamic fracture problem, there is only some specially problem can be given solution, a majority of problem cann't obtain theoretical solution, it has to take advantage of numerical analysis. Utilizing J-integral express the average parameter of stress concentration of crack tip, which can avoid calculating strain-stress field of elastic-plastic material around the tip of crack directly.The paper has been considered that the crack tip has a definite curvature radius, then having an elastic-plastic dynamic FEM analysis on circumferentially notched specimen under bar-bar tensile impact apparatus. It has been calculated ten contour J-integals at different times and compared the value of J-integral, then it can be obtain the influence on conservation of J-integral under different curvature radius. Utilizing the contour J-integral of crack tip which is obtained by FEM analysis directly,comparing the J-Δ curve under three depth ratios which has been considered curvature radius with the infinite tine crack, discussing the influence of different curvature radius of notch to J-integral, for the next test offer the base of numerical analysis.The average load-average displacement curve of circumferentially notched specimen can be gained by FEM analysis. We can use this curve to generalize the farfield J-integral formula by Rice. If we compare J - Δ curve with J - Δ curve and analysis the influence of Rice far field J-integral under different curvature radius, we will find out the influence on dynamic J-integral further.