油田常用橡胶断裂韧性的实验测定

给出了带裂纹橡胶零件的开裂判据Ｊ≥ＪＣ。由标准橡胶试件的实验发现， 试件拉断时的最大载荷和裂纹开始启裂时的临界载荷， 均与裂纹相对深度ａ／ ｗ 呈线性关系， 且随着裂纹相对深度的增加而减小。利用载荷位移曲线上的裂纹启裂点拟合出了裂纹启裂迹线， 进而采用裂纹启裂迹线法测定了油田常用橡胶的临界Ｊ积分值（ 断裂韧性） ， 计算时去除了远离裂尖区域所吸收的能量， 得到４ 种橡胶的临界Ｊ积分值， 即２４０ 号橡胶的ＪＣ＝ ７－１５ ×１０ － ３Ｊ／ｍｍ２ ； ８０２ 号橡胶的ＪＣ＝４－７８ ×１０－ ３Ｊ／ｍｍ２ ； ８１３ 号橡胶的ＪＣ＝ ３－８５ ×１０ － ３Ｊ／ｍｍ２ ； ８１４ 号橡胶的ＪＣ＝ ３－６９×１０ － ３Ｊ／ｍｍ２ 。

Experimental determination of the fracture toughness of rubber usually used in oilfields

The fracture criterion of rubber parts with crack is given, and the fracture problem of rubber usually used in oilfields is investigated. Based on the experiment of standard rubber specimen, it is observed that both maximum load per unit thickness ( F max / B ) and critical load per unit thickness ( F cr / B ) are linear with the relative length of crack ( a/w ), and their values decrease as the relative length of crack increases. Crack initiation locus is fitted by the incipient crack points on the load displacement curves. The crack initiation locus method is used to determine the fracture toughness (critical J integral J c ) of rubber usually used in oilfields, and the values J c of 4 kinds of rubbers are obtained.