1.1 本实践涵盖了先进陶瓷在环境温度下的恒幅、轴向、拉伸-拉伸循环疲劳行为和性能的测定，以建立“基线”循环疲劳性能。本实践建立在环境温度下高级陶瓷拉伸测试的经验和现有标准的基础上，并解决了各种建议的试样几何形状、试样制造方法、测试模式（力、位移或应变控制）、测试速率和频率、允许弯曲以及数据收集和报告程序。本惯例不适用于部件或零件（即具有非均匀或多轴应力状态的机器元件）的轴向循环疲劳试验。 1.2 该实践主要适用于宏观上表现出各向同性、均匀、连续行为的高级陶瓷。虽然该实践主要适用于整体式高级陶瓷，但某些晶须或颗粒增强复合陶瓷以及某些不连续纤维增强复合陶瓷也可能满足这些宏观行为假设。通常，连续纤维增强陶瓷复合材料（CFCCs）在宏观上不表现出各向同性、均匀、连续的行为，不推荐将这种做法应用于这些材料。 1.3 以国际单位制单位表示的数值将被视为标准，并符合 IEEE/ASTM SI 10 . 1.4 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。参考章节 7 具体的预防措施。 1.5 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》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 4.1 该实践可用于材料开发、材料比较、质量保证、表征、可靠性评估和设计数据生成。 4.2 高强度、整体式先进陶瓷材料通常以小晶粒尺寸（<50 μ m）和接近理论密度的堆积密度为特征。这些材料是需要高度耐磨性和耐腐蚀性的承重结构应用的候选材料，并且-温度强度。尽管弯曲测试方法通常用于评估先进陶瓷的强度，但弯曲试样中的不均匀应力分布限制了断裂时承受最大施加应力的材料体积。单轴加载拉伸强度测试可以提供关于较大体积均匀应力材料的强度限制缺陷的信息。 4.3 循环疲劳本质上是一种概率现象，如STP 91A和STP 588中所讨论的 ( 1 , 2 ) . 5 此外，先进陶瓷的强度本质上是概率性的。因此，统计分析和设计需要在每个测试条件下有足够数量的测试样本，STP 91A中提供了足够数量的指南 ( 1 ) ,STP 588 ( 2 ) ，并练习 E739 可用于循环疲劳测试的许多不同拉伸样本几何形状可能导致特定材料的测量循环疲劳行为的变化，这是由于测试样本的规格区段中材料的体积或表面积的差异。 4.4 拉伸循环疲劳试验提供了波动单轴拉伸应力下材料响应的信息。需要均匀的应力状态来有效地评估任何非线性应力-应变行为，这些行为可能是累积损伤过程的结果（例如，微裂纹、循环疲劳裂纹扩展等）。）. 4.5 循环疲劳引起的累积损伤过程可能受到测试模式、测试速率（与频率相关）、最大和最小力之间的差异（ R 或A)、加工的影响或组成材料的组合、或环境影响、或两者。影响循环疲劳行为的其他因素有:空隙或孔隙率含量、试样制备或制造方法、试样调节、试验环境、循环期间的力或应变极限、波形（即正弦、梯形等）和失效模式。这些影响中的一些可能是应力腐蚀或亚临界（缓慢）裂纹扩展的结果，这可能难以量化。此外，由测试样本制造过程（机械加工）引入的表面或近表面缺陷可以或可以不通过表面纹理的常规测量来量化。因此，表面效应（例如，反映在Marin分类的循环疲劳降低因子中 ( 3 ) ）必须从使用具有相同制造历史的试样进行的大量循环疲劳试验的结果中推断出来。 4.6 由特定材料或零件的选定部分或两者制造成标准化尺寸的样品的循环疲劳测试结果可能不能完全代表整个全尺寸最终产品的循环疲劳行为或其在不同环境中的使用行为。 4.7 然而，出于质量控制的目的，从标准化拉伸测试样本得出的结果可以被认为指示了从其获取的材料对于给定的初级加工条件和加工后热处理的响应。 4.8 高级陶瓷的循环疲劳行为取决于其固有的抗断裂性、缺陷的存在或损伤积累过程，或两者兼而有之。在没有任何视觉证据（例如宏观裂纹的出现）的情况下，试样中可能存在显著的损伤。这可能导致刚度和保留强度的特定损失。取决于进行测试的目的，而不是最终断裂，刚度或保留强度的特定损失可能构成失效。在发生断裂的情况下，尽管超出了本实践的范围，但建议对断裂表面和断口进行分析。

1.1 This practice covers the determination of constant-amplitude, axial, tension-tension cyclic fatigue behavior and performance of advanced ceramics at ambient temperatures to establish “baseline” cyclic fatigue performance. This practice builds on experience and existing standards in tensile testing advanced ceramics at ambient temperatures and addresses various suggested test specimen geometries, test specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates and frequencies, allowable bending, and procedures for data collection and reporting. This practice does not apply to axial cyclic fatigue tests of components or parts (that is, machine elements with nonuniform or multiaxial stress states). 1.2 This practice applies primarily to advanced ceramics that macroscopically exhibit isotropic, homogeneous, continuous behavior. While this practice applies primarily to monolithic advanced ceramics, certain whisker- or particle-reinforced composite ceramics, as well as certain discontinuous fibre-reinforced composite ceramics, may also meet these macroscopic behavior assumptions. Generally, continuous fibre-reinforced ceramic composites (CFCCs) do not macroscopically exhibit isotropic, homogeneous, continuous behavior and application of this practice to these materials is not recommended. 1.3 The values stated in SI units are to be regarded as the standard and are in accordance with IEEE/ASTM SI 10 . 1.4 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. Refer to Section 7 for specific precautions. 1.5 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 ====== 4.1 This practice may be used for material development, material comparison, quality assurance, characterization, reliability assessment, and design data generation. 4.2 High-strength, monolithic advanced ceramic materials are generally characterized by small grain sizes (<50 μm) and bulk densities near the theoretical density. These materials are candidates for load-bearing structural applications requiring high degrees of wear and corrosion resistance, and high-temperature strength. Although flexural test methods are commonly used to evaluate strength of advanced ceramics, the nonuniform stress distribution in a flexure specimen limits the volume of material subjected to the maximum applied stress at fracture. Uniaxially loaded tensile strength tests may provide information on strength-limiting flaws from a greater volume of uniformly stressed material. 4.3 Cyclic fatigue by its nature is a probabilistic phenomenon as discussed in STP 91A and STP 588 ( 1 , 2 ) . 5 In addition, the strengths of advanced ceramics are probabilistic in nature. Therefore, a sufficient number of test specimens at each testing condition is required for statistical analysis and design, with guidelines for sufficient numbers provided in STP 91A ( 1 ) , STP 588 ( 2 ) , and Practice E739 . The many different tensile specimen geometries available for cyclic fatigue testing may result in variations in the measured cyclic fatigue behavior of a particular material due to differences in the volume or surface area of material in the gauge section of the test specimens. 4.4 Tensile cyclic fatigue tests provide information on the material response under fluctuating uniaxial tensile stresses. Uniform stress states are required to effectively evaluate any nonlinear stress-strain behavior which may develop as the result of cumulative damage processes (for example, microcracking, cyclic fatigue crack growth, etc.). 4.5 Cumulative damage processes due to cyclic fatigue may be influenced by testing mode, testing rate (related to frequency), differences between maximum and minimum force ( R or Α), effects of processing or combinations of constituent materials, or environmental influences, or both. Other factors that influence cyclic fatigue behavior are: void or porosity content, methods of test specimen preparation or fabrication, test specimen conditioning, test environment, force or strain limits during cycling, wave shapes (that is, sinusoidal, trapezoidal, etc.), and failure mode. Some of these effects may be consequences of stress corrosion or sub-critical (slow) crack growth which can be difficult to quantify. In addition, surface or near-surface flaws introduced by the test specimen fabrication process (machining) may or may not be quantifiable by conventional measurements of surface texture. Therefore, surface effects (for example, as reflected in cyclic fatigue reduction factors as classified by Marin ( 3 ) ) must be inferred from the results of numerous cyclic fatigue tests performed with test specimens having identical fabrication histories. 4.6 The results of cyclic fatigue tests of specimens fabricated to standardized dimensions from a particular material or selected portions of a part, or both, may not totally represent the cyclic fatigue behavior of the entire full-size end product or its in-service behavior in different environments. 4.7 However, for quality control purposes, results derived from standardized tensile test specimens may be considered indicative of the response of the material from which they were taken for given primary processing conditions and post-processing heat treatments. 4.8 The cyclic fatigue behavior of an advanced ceramic is dependent on its inherent resistance to fracture, the presence of flaws, or damage accumulation processes, or both. There can be significant damage in the test specimen without any visual evidence such as the occurrence of a macroscopic crack. This can result in a specific loss of stiffness and retained strength. Depending on the purpose for which the test is being conducted, rather than final fracture, a specific loss in stiffness or retained strength may constitute failure. In cases where fracture occurs, analysis of fracture surfaces and fractography, though beyond the scope of this practice, are recommended.