1.1 本实践涵盖了连续纤维增强高级陶瓷复合材料（CFCCs）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。该实践建立在环境温度下CFCC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测试样本几何形状、样本制造方法、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 本规范主要适用于具有连续纤维增强的先进陶瓷基复合材料:单向(1-D)、双向(2-D)和三向(3-D)或其他多向加强件。此外，该实践也可用于具有1-D、2-D、3-D和其他多方向连续纤维增强物的玻璃(无定形)基质复合材料。该实践不直接涉及不连续纤维增强、晶须增强或颗粒增强陶瓷，尽管这里详述的方法可以同样适用于这些复合材料。 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 连续纤维增强陶瓷基复合材料通常以结晶基体和陶瓷纤维增强体为特征。这些材料是要求高耐磨性和耐腐蚀性的结构应用的候选材料，并且-温度固有损伤容限（即韧性）。此外，连续纤维增强玻璃基复合材料是类似但可能要求较低的应用的候选材料。尽管弯曲试验方法通常用于评估整体先进陶瓷的机械性能，但弯曲试样中的不均匀应力分布以及CFCC在拉伸和压缩中的不同机械性能导致CFCC在弯曲中获得的试验结果的解释不明确。单轴加载拉伸试验提供了关于均匀应力材料的机械性能的信息。 4.3 CFCC的循环疲劳行为可能具有明显的非线性效应（例如，纤维在基体中的滑动），这可能与样品向周围环境的热传递有关。测试温度、频率和散热的变化会影响测试结果。可能需要测量这些变量的影响，以更接近地模拟某些特定应用的最终使用条件。 4.4 循环疲劳本质上是STP 91A中讨论的概率现象 ( 1 ) 和STP 588 ( 2 ) . 4 此外，CFCC的脆性基质和纤维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 确定试样体积或表面积对CFCC循环疲劳强度分布影响的研究尚未完成。可用于循环疲劳测试的许多不同拉伸测试样本几何形状可能由于测试样本的计量区段中材料体积的差异而导致特定材料的测量循环疲劳行为的变化。 4.5 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，基体微裂纹、纤维/基体脱粘、分层、循环疲劳裂纹扩展等） 4.6 循环疲劳引起的累积损伤可能受到测试模式、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、环境影响(包括测试环境和测试前调节)或其组合。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。可能影响循环疲劳行为的其他因素有:基体或纤维材料、空隙或孔隙率含量、试样制备或制造方法、增强体的体积百分比、增强体的取向和堆叠、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CFCC的失效模式。 4.7 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试样的循环疲劳试验结果可能不能完全代表整个、全-确定最终产品或其在不同环境中的使用行为的尺寸。 4.8 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。 4.9 CFCC的循环疲劳行为取决于其固有的抗断裂性、缺陷的存在或损伤累积过程或两者。CFCC测试样本中可能存在显著损坏，而没有任何视觉证据，例如宏观裂纹的出现。这可能导致刚度和保留强度的损失。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，建议对断裂表面和断口成像进行分析，尽管超出了本实践的范围。

1.1 This practice covers the determination of constant-amplitude, axial tension-tension cyclic fatigue behavior and performance of continuous fiber-reinforced advanced ceramic composites (CFCCs) at ambient temperatures. This practice builds on experience and existing standards in tensile testing CFCCs at ambient temperatures and addresses various suggested test specimen geometries, 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 ceramic matrix composites with continuous fiber reinforcement: uni-directional (1-D), bi-directional (2-D), and tri-directional (3-D) or other multi-directional reinforcements. In addition, this practice may also be used with glass (amorphous) matrix composites with 1-D, 2-D, 3-D, and other multi-directional continuous fiber reinforcements. This practice does not directly address discontinuous fiber-reinforced, whisker-reinforced or particulate-reinforced ceramics, although the methods detailed here may be equally applicable to these composites. 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 Continuous fiber-reinforced ceramic matrix composites are generally characterized by crystalline matrices and ceramic fiber reinforcements. These materials are candidate materials for structural applications requiring high degrees of wear and corrosion resistance, and high-temperature inherent damage tolerance (that is, toughness). In addition, continuous fiber-reinforced glass matrix composites are candidate materials for similar but possibly less demanding applications. Although flexural test methods are commonly used to evaluate the mechanical behavior of monolithic advanced ceramics, the nonuniform stress distribution in a flexural test specimen in addition to dissimilar mechanical behavior in tension and compression for CFCCs leads to ambiguity of interpretation of test results obtained in flexure for CFCCs. Uniaxially loaded tensile tests provide information on mechanical behavior for a uniformly stressed material. 4.3 The cyclic fatigue behavior of CFCCs can have appreciable nonlinear effects (for example, sliding of fibers within the matrix) which may be related to the heat transfer of the specimen to the surroundings. Changes in test temperature, frequency, and heat removal can affect test results. It may be desirable to measure the effects of these variables to more closely simulate end-use conditions for some specific application. 4.4 Cyclic fatigue by its nature is a probabilistic phenomenon as discussed in STP 91A ( 1 ) and STP 588 ( 2 ) . 4 In addition, the strengths of the brittle matrices and fibers of CFCCs 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 . Studies to determine the influence of test specimen volume or surface area on cyclic fatigue strength distributions for CFCCs have not been completed. The many different tensile test 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 of material in the gauge section of the test specimens. 4.5 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, matrix microcracking, fiber/matrix debonding, delamination, cyclic fatigue crack growth, etc.) 4.6 Cumulative damage 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, environmental influences (including test environment and pre-test conditioning), or combinations thereof. Some of these effects may be consequences of stress corrosion or subcritical (slow) crack growth which can be difficult to quantify. Other factors which may influence cyclic fatigue behavior are: matrix or fiber material, void or porosity content, methods of test specimen preparation or fabrication, volume percent of the reinforcement, orientation and stacking of the reinforcement, test specimen conditioning, test environment, force or strain limits during cycling, wave shapes (that is, sinusoidal, trapezoidal, etc.), and failure mode of the CFCC. 4.7 The results of cyclic fatigue tests of test 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. 4.8 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. 4.9 The cyclic fatigue behavior of a CFCC 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 CFCC test specimen without any visual evidence such as the occurrence of a macroscopic crack. This can result in a 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, is recommended.