材料期刊网

多次冲击条件下裂纹尖端应力强度因子的表达式为K_I=(AE/BW)~(1/2)·F(a/W)。经柔度法标定,其临界值可用以度量材料的断裂韧性。所得结果相当于加载速率为k=10~5公斤/毫米~(3/2)/秒下的动态断裂韧性K_(Id)。断口上临界裂纹尺寸在(a/W)=0.36-0.6范围内,结果有效。多次冲击法较为简便,只需测出断口上的临界裂纹尺寸,便可在已绘好的曲线上直接查出材料的断裂韧性。在实际生产中可以作为一种筛选方法应用。

The crack tip stress intensity factor under impact-fatigue conditions expressed by the equation K_I=(AE/BW)~(1/2)·F(a/W) may be used as a measure of fracture toughness of materials on condition that a proper calibration of K_I with the compliance measurements is made. The fracture toughness values obtained by the above method are equivalent to the dynamic fracture toughness K_(Id) with loading rate of the order (?)=10~5kg/mm~(3/2)/sec, and would be valid as the critical crack length of the fracture surface of specimens are constrained within the range of a/W=0.36-0.6.The above method is simple and convenient for testing fracture toughness of materials. The testing results may be obtained directly from a ready made curve provided that the critical crack length on fracture surface has been predetermined. It can be recommended as a screen method in practical work.