在裂纹有限扩展时 Garwood 假设的修正及应用

Revisal and application of the Garwood hypothesis during finite crack extension

对修正的Ｇａｒｗｏｏｄ假设作进一步论证。该假设指，当预裂试件与相应静裂纹试件的外载荷Ｐ、位移Ｖ相等时，其实时裂纹长度ａ也相等。以前的验证是基于少数实验结果，定量显得不够。最近Ｌａｎｄｅｓ等用载荷分离法对多种材料塑性因子和规则化载荷－塑性位移曲线作了系统研究，这就为进一步论证创造了条件。结果表明，修正的Ｇａｒｗｏｏｄ假设的正确性是肯定的。按照这一假设，可用静裂纹塑性位移解求解预裂试件实时裂纹长度，并校核实测结果，也为规则化方法寻找补充标定点提供依据。

A revised Garwood hypothesis is further demonstrated. The revised hypothesis means that a stationary crack speciment and a corresponding precracked specimen will have a equal current crack length when their load P and displacement V are equal, respectively. Previous experiment check is based on a few test results, it is not enough to prove this revised hypothesis. Recently, Landes et al. systematically investigated plastic factor of many kinds of material and normalized load versus plastic displacement records using load separation method. It provides powerful backing for demonstrating the revised hypothesis. It is showed that the validity of the revised hypothesis is affirmative. The revised hypothesis will provide a basis for evaluating the current crack lengths of the precracked speciment and checking the experiment measure results by using the stationary crack speciment plastic displacement solution and for seeking new calibration points in normalization method.