塑料. 拉伸-拉伸疲劳断裂延伸性的测定. 线性弹力断裂机械(LEFM)方法

[中文适用范围]： 本国际标准规定了测量在恒定正最小值和恒定正最大值之间变化的循环拉伸载荷下缺口试样中裂纹扩展的方法。 测试结果包括作为载荷循环次数函数的裂纹长度以及作为应力强度因子和裂纹尖端能量释放速率函数的裂纹长度增加率。 检测并报告裂纹扩展中可能出现的不连续性。 该测试还可用于确定抗裂纹扩展失效能力。 在这种情况下，结果可以以失效周期数或导致裂纹扩展失效所需的总时间与应力强度因子的形式呈现（参见附录 A）。 该方法适用于以下范围的材料： ——刚性和半刚性热塑性模制和挤出材料（包括填充和短纤维增强化合物）以及刚性和半刚性热塑性片材； ——刚性和半刚性热固性材料（包括填充和短纤维增强化合物）以及刚性和半刚性热固性板材。 [外文原描述]： ISO 15850:2014 specifies a method for measuring the propagation of a crack in a notched specimen subjected to a cyclic tensile load varying between a constant positive minimum and a constant positive maximum value. The test results include the crack length as a function of the number of load cycles and the crack length increase rate as a function of the stress intensity factor and energy release rate at the crack tip. The possible occurrence of discontinuities in crack propagation is detected and reported. The test can be also used for the purpose of determining the resistance to crack propagation failure. In this case, the results can be presented in the form of number of cycles to failure or total time taken to cause crack propagation failure versus the stress intensity factor.