1.1 本试验方法包括测定塑料材料标准拉伸冲击试样断裂所需的能量。刚性材料适用于通过该方法进行试验，以及根据其他冲击试验方法进行试验的太软或太薄的试样。 1.2 以国际单位制表示的数值应视为标准值。括号中给出的值仅供参考。 注1: 本试验方法和 ISO 8256 解决相同的主题，但技术内容不同。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户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。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 拉伸冲击能量是指在一组标准条件下，通过标准校准摆锤的单次摆动使标准拉伸冲击试样断裂所需的能量（见 注释2 ). 为了补偿试样横截面积的微小差异，将断裂能量归一化为最小横截面积的千焦/平方米（或英尺-磅力/平方英寸）单位。 第节中显示了一种归一化冲击能量的替代方法，该方法补偿了这些微小差异，并仍将试验单位保留为焦耳（英尺磅） 10 . 对于完全弹性材料，冲击能量通常是每单位体积的变形材料报告的。然而，由于用于破坏本试验方法的塑料材料的大部分能量仅在绘制试验区域的一部分时消耗，因此这种基于体积的归一化是不可行的。为了观察延伸率或延伸率或两者对结果的影响，试验方法允许两种试样几何形状。使用不同容量机器获得的结果通常不具有可比性。 5.1.1 S型（短）试样的延伸率相对较低，而L型（长）试样的延伸率相对较高。 一般来说，S型试样（脆性断裂发生率较高）具有较高的再现性，但材料之间的差异较小。 注2: 通过仔细设计和正确操作试验机，可以在很大程度上消除摩擦损失。 5.2 数据分散有时归因于一组样本内的不同失效机制。一些材料表现出不同失效机制之间的过渡。如果是这样，延伸率将严重取决于试验中遇到的延伸率。一组此类试样的冲击能量值将具有异常大的分散性。 5.2.1 一些材料在失效时收缩，永久变形很小。对于此类材料，通过检查碎片来确定失效类型（韧性或脆性）即使不是不可能，也是很困难的。 通过观察碎片，将一组试样分为两组，以确定试验期间是否有颈缩。定性而言，此处遇到的应变率介于试验方法的高Izod试验之间 D256 以及按照试验方法进行常规拉伸试验的低比率 D638 . 5.3 断裂能量是力乘以力作用距离的函数。因此，给定相同的试样几何形状，一种材料可能会由于与小伸长率相关的较大力而产生断裂冲击能，而另一种材料可能会由于与大伸长率相关的较小力而产生相同的断裂能量。除非通过实验建立了这种相关性，否则不得假设该试验方法将与其他试验或最终用途相关。 5.4 只有在准确复制了试样制备（例如成型历史）的情况下，才能对不同来源的试样进行比较。在未首先定量确定两种制备方法之间固有的差异之前，不得对模制试样和机加工试样进行比较。 5.5 除非已经证明，归一化为横截面积千焦/平方米（或英尺-磅力/平方英寸）的拉伸冲击能量与所考虑厚度范围内的厚度无关，否则只能比较标称厚度和标签宽度相等的试样的结果。 5.6 十字头的反弹为断裂试样提供了部分能量（参见 附录X1 ). 5.7 对于许多材料，有一些规范要求使用该试验方法，但在遵守规范时，一些程序修改优先。因此，建议在使用本试验方法之前参考该材料规范。分类系统表1 D4000 列出了当前存在的ASTM材料标准。

1.1 This test method covers the determination of the energy required to rupture standard tension-impact specimens of plastic materials. Rigid materials are suitable for testing by this method as well as specimens that are too flexible or thin to be tested in accordance with other impact test methods. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. Note 1: This test method and ISO 8256 address the same subject matter, but differ in technical content. 1.3 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. 1.4 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 Tensile-impact energy is the energy required to break a standard tension-impact specimen in tension by a single swing of a standard calibrated pendulum under a set of standard conditions (see Note 2 ). To compensate for the minor differences in cross-sectional area of the specimens, the energy to break is normalized to units of kilojoules per square metre (or foot-pounds-force per square inch) of minimum cross-sectional area. An alternative approach to normalizing the impact energy that compensates for these minor differences and still retains the test unit as joules (foot-pounds) is shown in Section 10 . For a perfectly elastic material, the impact energy is usually reported per unit volume of material undergoing deformation. However, since much of the energy to break the plastic materials for which this test method is written is dissipated in drawing of only a portion of the test region, such normalization on a volume basis is not feasible. In order to observe the effect of elongation or rate of extension, or both, upon the result, the test method permits two specimen geometries. Results obtained with different capacity machines generally are not comparable. 5.1.1 With the Type S (short) specimen the extension is comparatively low, while with the Type L (long) specimen the extension is comparatively high. In general, the Type S specimen (with its greater occurrence of brittle fracture) gives greater reproducibility, but less differentiation among materials. Note 2: Friction losses are largely eliminated by careful design and proper operation of the testing machine. 5.2 Scatter of data is sometimes attributed to different failure mechanisms within a group of specimens. Some materials exhibit a transition between different failure mechanisms. If so, the elongation will be critically dependent on the rate of extension encountered in the test. The impact energy values for a group of such specimens will have an abnormally large dispersion. 5.2.1 Some materials retract at failure with insignificant permanent set. With such materials, determining the type of failure, ductile or brittle, by examining the broken pieces is difficult, if not impossible. It is helpful to sort a set of specimens into two groups by observing the broken pieces to ascertain whether or not there was necking during the test. Qualitatively, the strain rates encountered here are intermediate between the high rate of the Izod test of Test Methods D256 and the low rate of usual tension testing in accordance with Test Method D638 . 5.3 The energy for fracture is a function of the force times the distance through which the force operates. Therefore, given the same specimen geometry, it is possible that one material will produce tensile-impact energies for fracture due to a large force associated with a small elongation, and another material will produce the same energy for fracture result due to a small force associated with a large elongation. It shall not be assumed that this test method will correlate with other tests or end uses unless such a correlation has been established by experiment. 5.4 Comparisons among specimens from different sources are to be made with confidence only to the extent that specimen preparation, for example, molding history, has been precisely duplicated. Comparisons between molded and machined specimens must not be made without first establishing quantitatively the differences inherent between the two methods of preparation. 5.5 Only results from specimens of nominally equal thickness and tab width shall be compared unless it has been shown that the tensile-impact energy normalized to kilojoules per square metre (or foot-pounds-force per square inch) of cross-sectional area is independent of the thickness over the range of thicknesses under consideration. 5.6 The bounce of the crosshead supplies part of the energy to fracture test specimen (see Appendix X1 ). 5.7 For many materials, there are specifications that require the use of this test method, but with some procedural modifications that take precedence when adhering to the specification. Therefore, it is advisable to refer to that material specification before using this test method. Table 1 of Classification System D4000 lists the ASTM materials standards that currently exist.