1.1 本试验方法包括测定弯曲塑料的动态疲劳性能。该方法适用于刚性和半刚性塑料。应力和应变水平低于材料的比例极限，其中应变和应力相对弹性。三点或四点弯曲系统用于确定这些特性。 1.2 本试验方法可用于两个程序: 1.2.1 程序A， 设计用于使用三点加载系统来确定弯曲强度的材料。该程序使用三点加载系统。 1.2.2 程序B， 设计用于使用四点加载系统来确定弯曲强度的材料。该程序使用四点加载系统。 1.3 可根据任一程序进行比较试验，前提是该程序符合所测试材料的要求。 1.4 以国际单位制表示的数值应视为标准。括号中提供的值仅供参考。 1.5 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1: 本标准和ISO 13003涉及相同的主题，但技术内容不同，无法直接比较两种试验方法之间的结果。 1.6 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 这些疲劳试验用于确定加工、表面条件、应力等对承受相对大量循环弯曲应力的塑料材料的疲劳抗力的影响。研究结果也可作为在重复弯曲应力条件下选择使用的塑料材料的指南。 5.2 特性可能随试样深度和测试频率而变化。测试频率可以是1-25 Hz，但建议使用5 Hz或更低的频率。 5.3 并非所有塑料的材料疲劳响应都相同。如果塑料没有表现出应变可逆的弹性区域，则在疲劳试验期间会发生塑性变形，导致编程载荷或变形的幅度在试验期间发生变化。在这种情况下，在使用结果进行设计时应小心，因为这些结果通常不能表明材料的真实疲劳性能。 5.4 只有当试样试验条件真实地模拟了使用条件或某些计算使用条件的方法可用且定义明确时，这些疲劳试验的结果才适合在设计中应用。 5.5 该程序适用于各种试样制备技术。除非证明了等效性，否则不应将以不同方式制备的试样所得结果进行比较。

1.1 This test method covers the determination of dynamic fatigue properties of plastics in flexure. This method is applicable to rigid and semi-rigid plastics. Stress and strain levels are below the proportional limit of the material where the strains and stresses are relatively elastic. Three-point or four-point bending systems are used to determine these properties. 1.2 This test method can be used with two procedures: 1.2.1 Procedure A, designed for materials that use three-point loading systems to determine flexural strength. Three-point loading system is used for this procedure. 1.2.2 Procedure B, designed for materials that use four-point loading systems to determine flexural strength. Four-point loading system is used for this procedure. 1.3 Comparative tests can be run in accordance with either procedure, provided that the procedure is found satisfactory for the material being tested. 1.4 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are 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. Note 1: This standard and ISO 13003 address the same subject matter, but differ in technical content and results cannot be directly compared between the two test methods. 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 These fatigue tests are used to determine the effect of processing, surface condition, stress, and so forth, on the fatigue resistance of plastic material subjected to flexural stress for relatively large numbers of cycles. The results can also be used as a guide for the selection of plastic materials for service under conditions of repeated flexural stress. 5.2 Properties can vary with specimen depth and test frequency. Test frequency can be 1-25 Hz but it is recommended that a frequency of 5 Hz or less be used. 5.3 Material response in fatigue is not identical for all plastics. If a plastic does not exhibit an elastic region, where strain is reversible, plastic deformation will occur during fatigue testing, causing the amplitude of the programmed load or deformation to change during testing. In this situation, caution shall be taken when using the results for design as they are generally not indicative of the true fatigue properties of the material. 5.4 The results of these fatigue tests are suitable for application in design only when the specimen test conditions realistically simulate service conditions or some methodology of accounting for service conditions is available and clearly defined. 5.5 This procedure accommodates various specimen preparation techniques. Comparison of results obtained from specimens prepared in different manners shall not be considered comparable unless equivalency has been demonstrated.