1.1本试验方法包括在环境温度下测定管状高级陶瓷在单调载荷下的极限强度。本试验方法中使用的极限强度是指C型环试样在单调压缩载荷下获得的强度，如图1所示，其中单调是指从试验开始到最终断裂没有反转的连续不间断试验速率。该方法允许各种尺寸和形状，因为试样可以从各种管状结构中制备。 该方法可用于微型试样。 1.2以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.2.1本试验方法中表示的数值符合国际单位制（SI）和 . 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和健康实践，并确定监管限制的适用性。 ====意义和用途====== 本试验方法可用于材料开发、材料比较、质量保证和表征。生成设计数据时应格外小心。 对于承受径向压缩的C型环，最大拉伸应力发生在外表面。因此，压缩加载的C形环试样将主要评估管状部件外表面上的强度分布和缺陷分布。因此，内表面的状况可能对试样制备和测试影响较小。 笔记 1-可使用受拉C型环或受压O型环来评估内表面。 基于简单曲梁理论计算弯曲应力 (1, 2, 3, 4, 5) . 假设材料是各向同性和均匀的，弹性模量在压缩或拉伸时相同，并且材料是线性弹性的。这些均匀性和各向同性假设排除了将本标准用于连续纤维增强复合材料的可能性。平均晶粒度不应大于五十分之一( 1. / 50 )C型环厚度。对于本标准选择的几何形状，简单曲梁理论应力解与（3）中讨论的弹性理论解非常吻合（通常优于1%）。简单梁理论应力方程相对简单。对于Weibull有效体积或有效面积计算，它们相对容易集成，如附录X1所示。 简单曲梁和弹性应力解理论都是二维平面应力解。 它们不考虑轴向应力（平行于 b） 圆周方向或变化（环， σ θ )通过宽度的应力( b )测试件的。周向应力的变化随宽度的增加而增加( b )和环厚度( t ). 对于尺寸较大的试样，变化可能很大（>10%） b . 周向应力在外缘处达到峰值。因此，宽度( b )和厚度( t )本试验方法中允许的试样数量有限，因此轴向应力可以忽略不计（见参考。 5） 名义简单曲梁理论应力计算的周向应力变化通常小于4%。有关环向应力随环厚度变化的更多信息，请参阅参考文献（3）和（4）( t )和环宽度( b ). 试件外缘角容易受到边缘损伤，这是将环外表面上的周向应力差降至最低的另一个原因。 其他几何形状C – 可以测试环形试样，但应进行全面的有限元分析，以获得准确的应力分布。 如果强度将按比例（转换）为其他尺寸或几何形状的强度，则应使用有限元分析结果计算威布尔有效体积或面积。 由于表现出脆性行为的高级陶瓷通常因特定拉伸应力场的单一主要缺陷而发生灾难性断裂，因此承受拉伸应力的材料的表面积和体积是决定极限强度的一个重要因素。此外，由于表现出脆性行为的高级陶瓷中缺陷群的统计分布，在每个测试条件下需要足够数量的样本进行统计分析和设计。 本试验方法提供了应为此目的进行试验的样本数量指南（见8.4）。 由于与材料加工和部件制造相关的多种因素，特定材料或零件的选定部分或两者的C形环测试结果可能不一定代表全尺寸最终产品的强度和变形特性或其在役行为。 陶瓷材料的极限强度可能受缓慢裂纹扩展或应力腐蚀或两者的影响，因此对测试模式、测试速率或环境影响或其组合敏感。 按照本试验方法中概述的足够快的速度进行试验，可以最大限度地减少亚临界（缓慢）裂纹扩展或应力腐蚀的后果。 高级单片陶瓷的弯曲行为和强度取决于材料的固有抗断裂能力、缺陷的存在或损伤累积过程或其组合。强烈建议对断裂面和断口进行分析，尽管这超出了本试验方法的范围（可从实践中获得进一步指导 C1322 和Ref (6) ).

1.1 This test method covers the determination of ultimate strength under monotonic loading of advanced ceramics in tubular form at ambient temperatures. The ultimate strength as used in this test method refers to the strength obtained under monotonic compressive loading of C-ring specimens such as shown in Fig. 1 where monotonic refers to a continuous nonstop test rate with no reversals from test initiation to final fracture. This method permits a range of sizes and shapes since test specimens may be prepared from a variety of tubular structures. The method may be used with microminiature test specimens. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.2.1 Values expressed in this test method are in accordance with the International System of Units (SI) and . 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== This test method may be used for material development, material comparison, quality assurance, and characterization. Extreme care should be exercised when generating design data. For a C-ring under diametral compression, the maximum tensile stress occurs at the outer surface. Hence, the C-ring specimen loaded in compression will predominately evaluate the strength distribution and flaw population(s) on the external surface of a tubular component. Accordingly, the condition of the inner surface may be of lesser consequence in specimen preparation and testing. Note 1—A C-ring in tension or an O-ring in compression may be used to evaluate the internal surface. The flexure stress is computed based on simple curved-beam theory (1, 2, 3, 4, 5) . It is assumed that the material is isotropic and homogeneous, the moduli of elasticity are identical in compression or tension, and the material is linearly elastic. These homogeneity and isotropy assumptions preclude the use of this standard for continuous fiber reinforced composites. Average grain size(s) should be no greater than one fiftieth ( 1 / 50 ) of the C-ring thickness. The simple curved-beam theory stress solution is in good agreement (typically better than 1%) with a theory of elasticity solution as discussed in (3) for the geometries chosen for this standard. The simple beam theory stress equations are relatively simple. They are relatively easy to integrate for Weibull effective volume or effective area computations as shown in Appendix X1. The simple curved beam and theory of elasticity stress solutions both are two-dimensional plane stress solutions. They do not account for stresses in the axial (parallel to b) direction, or variations in the circumferential (hoop, σ θ ) stresses through the width ( b ) of the test piece. The variations in the circumferential stresses increase with increases in width ( b ) and ring thickness ( t ). The variations can be substantial (> 10 %) for test specimens with large b . The circumferential stresses peak at the outer edges. Therefore, the width ( b ) and thickness ( t ) of the specimens permitted in this test method are limited so that axial stresses are negligible (see Ref. 5) and the variations of the circumferential stresses from the nominal simple curved beam theory stress calculations are typically less than 4 %. See Ref. (3) and (4) for more information on the variation of the circumferential stresses as a function of ring thickness ( t ) and ring width ( b ). The test piece outer rim corners are vulnerable to edge damage, another reason to minimize the differences in the circumferential stresses across the ring outer surface. Other geometry C – ring test specimens may be tested, but comprehensive finite element analyses shall be performed to obtain accurate stress distributions. If strengths are to be scaled (converted) to strengths of other sizes or geometries, then Weibull effective volumes or areas shall be computed using the results of the finite element analyses. Because advanced ceramics exhibiting brittle behavior generally fracture catastrophically from a single dominant flaw for a particular tensile stress field, the surface area and volume of material subjected to tensile stresses is a significant factor in determining the ultimate strength. Moreover, because of the statistical distribution of the flaw population(s) in advanced ceramics exhibiting brittle behavior, a sufficient number of specimens at each testing condition is required for statistical analysis and design. This test method provides guidelines for the number of specimens that should be tested for these purposes (see 8.4). Because of a multitude of factors related to materials processing and component fabrication, the results of C-ring tests from a particular material or selected portions of a part, or both, may not necessarily represent the strength and deformation properties of the full-size end product or its in-service behavior. The ultimate strength of a ceramic material may be influenced by slow crack growth or stress corrosion, or both, and is therefore, sensitive to the testing mode, testing rate, or environmental influences, or a combination thereof. Testing at sufficiently rapid rates as outlined in this test method may minimize the consequences of subcritical (slow) crack growth or stress corrosion. The flexural behavior and strength of an advanced monolithic ceramic are dependent on the material's inherent resistance to fracture, the presence of flaws, or damage accumulation processes, or a combination thereof. Analysis of fracture surfaces and fractography, though beyond the scope of this test method, is highly recommended (further guidance may be obtained from Practice C1322 and Ref (6) ).