1.1 本试验方法用于测定塑料抗弯曲冲击破坏的能力，如从标准样品中提取的能量所示（见 注1 )摆锤，安装在标准化机器上，用一个摆锤摆动打破标准试样。本试验方法要求用铣削缺口制作试样（参见 注释2 ). 缺口产生的应力集中会促进脆性断裂，而不是韧性断裂。本试验方法的结果以每单位试样宽度吸收的能量进行报告（见 附注3 ). 注1: 配备摆锤的机器已经标准化，因为它们必须符合某些要求，包括固定的落锤高度，这导致冲击瞬间的落锤速度基本固定。 然而，建议将不同初始能量（通过改变其有效重量产生）的锤子用于不同抗冲击性的试样。此外，允许设备制造商使用不同长度和结构的摆锤，从而产生摆锤刚度的可能差异（见第节） 5. ). 请注意，机器设计中确实存在其他差异。 注2: 试样的标准化是因为它们具有固定的长度和深度，然而，试样的宽度允许在极限之间变化。允许一种铣削缺口设计。试样中的缺口用于集中应力，最小化塑性变形，并将断裂引导到缺口后面的试样部分。能量分散- 因此减少了断裂。然而，由于塑料弹性和粘弹性的差异，对给定缺口的响应因材料而异。 注3: 在解释本试验方法的结果时必须小心。以下测试参数对测试结果有显著影响:试样制作方法，包括但不限于加工技术、成型条件、模具设计和热处理；开槽方法；开槽工具的速度；开槽装置的设计；缺口质量；开槽和测试之间的时间；试样厚度；缺口下的试样宽度；和环境调节。 1.2 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。 注4: 本标准类似于ISO 仅标题179。内容明显不同。 1.3 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 在继续本试验方法之前，请参阅被测材料的材料规范。材料规范要求的任何试样制备、调节、尺寸和测试参数应优先于本试验方法要求的。 分类表1 D4000 列出了当前存在的ASTM材料标准。如果没有材料规范，则适用本试验方法的要求。 5.2 摆锤冲击试验表明，在规定的试样安装、开槽（应力集中）和冲击摆锤速度条件下，破坏规定尺寸标准试样的能量。 5.3 对于本试验方法，在试样断裂过程中，摆锤损失的能量是引发试样断裂所需能量的总和；使断裂在试样上传播；投掷断裂试样的自由端（投掷能量）；弯曲试样；在摆臂中产生振动；使机架或底座产生振动或水平移动； 克服摆锤轴承和指示机构中的摩擦，克服风阻（摆锤空气阻力）；使试样在冲击线上塑性缩进或变形；并克服撞击鼻在弯曲试样表面上摩擦产生的摩擦力。 注5: 在测试相对致密和脆性材料时，投掷能量或用于投掷断裂试样自由端的能量被怀疑占吸收总能量的很大一部分。尚未建立估算夏比法抛掷能量的程序。 5.4 对于韧性、韧性、纤维填充或布层压材料，与断裂起始能量相比，断裂传播能量通常较大。在测试这些材料时，由于断裂传播、振动、撞击鼻和试样之间的摩擦而产生的能量损失可能变得非常显著，即使试样经过精确加工和定位，并且机器处于良好状态且具有足够的容量（见 附注6 ). 在测试软材料时，还观察到由于弯曲和压痕而导致的显著能量损失。 注6: 尽管机器的框架和底座必须足够坚固和巨大，以在不移动或过度振动的情况下处理坚硬样本的能量，但摆臂不能变得非常巨大，因为其大部分质量必须集中在撞击头部的撞击中心附近。当与脆性试样一起使用时，将冲击头精确定位在冲击中心可以减少摆臂的振动。由于摆臂振动（数量随摆锤的设计而变化）导致的一些损失将在坚硬的试样上发生，即使敲击的头部位置正确。 5.5 在设计良好、具有足够刚度和质量的机器中，由于摆锤轴承和指示机构中的振动和摩擦而产生的损失将非常小。 当在质量不足的机器中或在未牢固固定在重型底座上的机器中测试坚硬材料的宽试样时，会观察到振动损失。 5.6 由于本试验方法允许试样宽度的变化，并且由于宽度决定了许多材料是脆性、低能断裂（通过很少或没有拉下或缩颈以及相对较低的能量吸收证明）还是韧性断裂，将发生高能断裂（如缺口后面区域的大量拉伸或缩颈以及相对较高的能量吸收所证明），有必要在涵盖该材料的规范中说明宽度，并将宽度与冲击值一起说明。 5.7 本试验方法要求试样完全断裂。 当使用没有足够能量完成极端纤维断裂和丢弃碎片的摆锤测试材料时，所获得的结果应被视为偏离标准，不得作为标准结果报告。对于经历不同类型失效的任何两种材料，不能直接比较冲击值。 5.8 这种冲击试验方法的价值主要体现在质量控制和材料规范方面。如果假设相同材料的两组试样显示出显著不同的能量吸收、临界宽度或临界温度，则允许假设它们由不同的材料制成，或暴露在不同的加工或调节环境中。在这些试验条件下，一种材料的能量吸收是另一种材料的两倍，这一事实并不表明在另一组试验条件下也会存在同样的关系。

1.1 This test method is used to determine the resistance of plastics to breakage by flexural shock as indicated by the energy extracted from standardized (see Note 1 ) pendulum-type hammers, mounted in standardized machines, in breaking standard specimens with one pendulum swing. This test method requires specimens to be made with a milled notch (see Note 2 ). The notch produces a stress concentration which promotes a brittle, rather than a ductile, fracture. The results of this test method are reported in terms of energy absorbed per unit of specimen width (see Note 3 ). Note 1: The machines with pendulum-type hammers have been standardized in that they must comply with certain requirements including a fixed height of hammer fall, which results in a substantially fixed velocity of the hammer at the moment of impact. Hammers of different initial energies (produced by varying their effective weights), however, are recommended for use with specimens of different impact resistance. Moreover, manufacturers of the equipment are permitted to use different lengths and constructions of pendulums with possible differences in pendulum rigidities resulting (see Section 5 ). Be aware that other differences in machine design do exist. Note 2: The specimens are standardized in that they have a fixed length and fixed depth, however, the width of the specimens is permitted to vary between limits. One design of milled notch is allowed. The notch in the specimen serves to concentrate the stress, minimize plastic deformation, and direct the fracture to the part of the specimen behind the notch. Scatter in energy-to-break is thus reduced. Because of differences in the elastic and viscoelastic properties of plastics, however, response to a given notch varies among materials. Note 3: Caution must be exercised in interpreting the results of this test method. The following testing parameters have been shown to affect test results significantly: method of specimen fabrication, including but not limited to processing technology, molding conditions, mold design, and thermal treatment; method of notching; speed of notching tool; design of notching apparatus; quality of the notch; time between notching and test; test specimen thickness; test specimen width under notch; and environmental conditioning. 1.2 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. Note 4: This standard resembles ISO 179 in title only. The content is significantly different. 1.3 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 Before proceeding with this test method, refer to the material specification for the material being tested. Any test specimen preparation, conditioning, dimensions and testing parameters required by the materials specification shall take precedence over those required by this test method. Table 1 of Classification D4000 lists the ASTM materials standards that currently exist. If there is no material specification, then the requirements of this test method apply. 5.2 The pendulum impact test indicates the energy to break standard test specimens of specified size under stipulated conditions of specimen mounting, notching (stress concentration), and pendulum velocity at impact. 5.3 For this test method, the energy lost by the pendulum during the breakage of the specimen is the sum of the energies required to initiate fracture of the specimen; to propagate the fracture across the specimen; to throw the free ends of the broken specimen (toss energy); to bend the specimen; to produce vibration in the pendulum arm; to produce vibration or horizontal movement of the machine frame or base; to overcome friction in the pendulum bearing and in the indicating mechanism, and to overcome windage (pendulum air drag); to indent or deform, plastically, the specimen at the line of impact; and to overcome the friction caused by the rubbing of the striking nose over the face of the bent specimen. Note 5: The toss energy, or the energy used to throw the free ends of the broken specimen, is suspected to represent a very large fraction of the total energy absorbed when testing relatively dense and brittle materials. No procedure has been established for estimating the toss energy for the Charpy method. 5.4 For tough, ductile, fiber-filled, or cloth-laminated materials, the fracture propagation energy is usually large compared to the fracture initiation energy. When testing these materials, energy losses due to fracture propagation, vibration, friction between the striking nose and the specimen has the potential to become quite significant, even when the specimen is accurately machined and positioned, and the machine is in good condition with adequate capacity (see Note 6 ). Significant energy losses due to bending and indentation when testing soft materials have also been observed. Note 6: Although the frame and the base of the machine must be sufficiently rigid and massive to handle the energies of tough specimens without motion or excessive vibration, the pendulum arm cannot be made very massive because the greater part of its mass must be concentrated near its center of percussion at its striking nose. Locating the striking nose precisely at the center of percussion reduces the vibration of the pendulum arm when used with brittle specimens. Some losses due to pendulum arm vibration (the amount varying with the design of the pendulum) will occur with tough specimens even when the striking nose is properly positioned. 5.5 In a well-designed machine of sufficient rigidity and mass, the losses due to vibration and friction in the pendulum bearing and in the indicating mechanism will be very small. Vibrational losses are observed when wide specimens of tough materials are tested in machines of insufficient mass, or in machines that are not securely fastened to a heavy base. 5.6 Since this test method permits a variation in the width of the specimens and since the width dictates, for many materials, whether a brittle, low-energy break (as evidenced by little or no drawing down or necking and by a relatively low energy absorption) or a ductile, high-energy break (as evidenced by considerable drawing or necking down in the region behind the notch and by a relatively high energy absorption) will occur, it is necessary that the width be stated in the specification covering that material and that the width be stated along with the impact value. 5.7 This test method requires that the specimen break completely. Results obtained when testing materials with a pendulum that does not have sufficient energy to complete the breaking of the extreme fibers and toss the broken pieces shall be considered a departure from standard and shall not be reported as a standard result. Impact values cannot be directly compared for any two materials that experience different types of failure. 5.8 The value of this impact test method lies mainly in the areas of quality control and materials specification. If two groups of specimens of supposedly the same material show significantly different energy absorptions, critical widths, or critical temperatures, it is permitted to assume that they were made of different materials or were exposed to different processing or conditioning environments. The fact that a material shows twice the energy absorption of another under these conditions of test does not indicate that this same relationship will exist under another set of test conditions.