1.1 该试验方法采用侧槽、裂纹线楔形加载试样，以获得具有几乎平直裂纹前缘的平坦拉伸分离的快速运行止动段。该试验方法提供了裂纹停止后短时间内应力强度因子的静态分析测定。估计值表示为 k 一 当满足一定的尺寸要求时，测试结果提供了一个估计值，称为 k Ia ，材料的平面应变止裂韧性。 1.2 稍后讨论的试样尺寸要求提供了足够大的平面内尺寸，以允许通过线性弹性分析对试样进行建模。对于平面应变条件，还需要最小试样厚度。这两个要求都取决于材料的止裂韧性和屈服强度。因此，根据本试验方法的规定，可能需要一定范围的试样尺寸。 1.3 如果试样没有表现出快速的裂纹扩展和停止， k 一 无法确定。 1.4 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 在包含韧性或应力梯度的结构中，裂纹可能在低韧性或高应力或两者兼有的区域中开始，并在较高韧性或较低应力或二者兼有的另一区域中停止。 在快速运行的裂纹停止的短时间间隔内的应力强度因子的值是材料停止这种裂纹的能力的度量。使用动力学分析方法确定的这种应力强度因子的值提供了一个止裂断裂韧性的值，该值将被称为 k a. 在本次讨论中。静态分析方法不那么复杂，通常可以用来确定 k 在裂纹停止后的短时间（1到2ms）。以这种方式获得的止裂断裂韧性的估计值称为 k 一 当宏观动力效应相对较小时 k a. 和 k 一 也很小 ( 1- 4. ) 对于在裂纹前平面应变条件下扩展的裂纹，在已知动态效应也很小的情况下， k Ia 实验室测定- 已经成功地使用尺寸大小的试样来估计结构中的裂纹是否会停止，以及在什么时候停止 ( 5. ， 6. ) 。根据部件设计、载荷顺应性和裂纹跳跃长度，可能需要对快速运行的裂纹扩展事件进行动态分析，以预测是否会发生裂纹止动和止动位置。在这种情况下，的值 k Ia 通过该测试方法确定的值可用于识别 k 低于该阈值，裂纹速度为零。有关使用动态分析的更多详细信息，请参阅参考文献 ( 4. ) 。 5.2 该试验方法至少可用于以下附加目的: 5.2.1 在材料研究和开发中，以定量的方式确定冶金变量（如成分或热处理）或制造操作（如焊接或成型）对新材料或现有材料阻止运行裂纹的能力的影响，这些变量对使用性能具有重要意义。 5.2.2 在设计中，协助选择加强筋和避雷板的材料，并确定其位置和尺寸。

1.1 This test method employs a side-grooved, crack-line-wedge-loaded specimen to obtain a rapid run-arrest segment of flat-tensile separation with a nearly straight crack front. This test method provides a static analysis determination of the stress intensity factor at a short time after crack arrest. The estimate is denoted K a . When certain size requirements are met, the test result provides an estimate, termed K Ia , of the plane-strain crack-arrest toughness of the material. 1.2 The specimen size requirements, discussed later, provide for in-plane dimensions large enough to allow the specimen to be modeled by linear elastic analysis. For conditions of plane-strain, a minimum specimen thickness is also required. Both requirements depend upon the crack arrest toughness and the yield strength of the material. A range of specimen sizes may therefore be needed, as specified in this test method. 1.3 If the specimen does not exhibit rapid crack propagation and arrest, K a cannot be determined. 1.4 The values stated in SI units are to be regarded as the standards. The values given in parentheses are provided for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 In structures containing gradients in either toughness or stress, a crack may initiate in a region of either low toughness or high stress, or both, and arrest in another region of either higher toughness or lower stress, or both. The value of the stress intensity factor during the short time interval in which a fast-running crack arrests is a measure of the ability of the material to arrest such a crack. Values of the stress intensity factor of this kind, which are determined using dynamic methods of analysis, provide a value for the crack-arrest fracture toughness which will be termed K A in this discussion. Static methods of analysis, which are much less complex, can often be used to determine K at a short time (1 to 2 ms) after crack arrest. The estimate of the crack-arrest fracture toughness obtained in this fashion is termed K a . When macroscopic dynamic effects are relatively small, the difference between K A and K a is also small ( 1- 4 ) . For cracks propagating under conditions of crack-front plane-strain, in situations where the dynamic effects are also known to be small, K Ia determinations using laboratory-sized specimens have been used successfully to estimate whether, and at what point, a crack will arrest in a structure ( 5 , 6 ) . Depending upon component design, loading compliance, and the crack jump length, a dynamic analysis of a fast-running crack propagation event may be necessary in order to predict whether crack arrest will occur and the arrest position. In such cases, values of K Ia determined by this test method can be used to identify those values of K below which the crack speed is zero. More details on the use of dynamic analyses can be found in Ref ( 4 ) . 5.2 This test method can serve at least the following additional purposes: 5.2.1 In materials research and development, to establish in quantitative terms significant to service performance, the effects of metallurgical variables (such as composition or heat treatment) or fabrication operations (such as welding or forming) on the ability of a new or existing material to arrest running cracks. 5.2.2 In design, to assist in selection of materials for, and determine locations and sizes of, stiffeners and arrestor plates.