1.1 本试验方法描述了测定连续纤维增强陶瓷基复合材料（CMC）材料临界模式I层间应变能释放率的实验方法和程序 G Ic 这种性质有时也被描述为I型断裂韧性或I型断裂阻力。 1.2 本试验方法主要适用于具有二维层压结构的陶瓷基复合材料，该结构由脆性陶瓷基质内单向带或二维编织织物结构中的连续陶瓷纤维叠层组成。 1.3 该试验方法确定了在两个或两个层板之间的层间界面上分层生长时，每单位新表面积释放的弹性应变能。 本试验方法中使用的术语分层专门指这种类型的生长，而术语裂纹是一个更通用的术语，也可以指基体开裂、层内分层生长或纤维断裂。 1.4 该试验方法使用双悬臂梁（DCB）试样来确定临界模式I层间应变能释放率( G Ic ). 根据测试方法，聚合物基复合材料（PMC）的DCB测试方法已经标准化 D5528 该测试方法解决了类似的程序，但进行了修改，以考虑CMC与PMC相比的不同物理性能、加固结构、应力-应变响应和失效机制。 1.5 本试验适用于环境温度和大气试验条件，但该试验方法也可用于高温或环境暴露试验，使用适当的环境试验箱、控制和测量试验箱温度、湿度和大气的测量设备、高温夹具和用于测量分层生长的改进设备。 1.6 以国际单位制表示的值应被视为标准值。本标准不包括其他计量单位。 1.6.1 本试验方法中表示的值符合国际单位制（SI）和 IEEE/asm SI 10 . 1. 7. 本标准并不旨在解决与其使用相关的所有安全问题（如果有的话）。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，并确定监管限制的适用性。 第节给出了具体的危害说明 8. . 1.8 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《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====== 5.1 层间分层生长可能是层压CMC结构的关键失效模式。了解层压CMC的层间分层生长阻力对于材料开发和选择以及CMC组件设计至关重要。（参见 ( 1. 8. ) 3. 这给了 G Ic 值为20 J/m 2. 至800焦耳/米 2. 适用于环境温度下的不同CMC和碳-碳复合材料系统。） 5.2 进行此测试会产生多个值 G Ic 传统上，这些值是根据测量该值的分层长度绘制的（参见 图2 ). 对测试请求者有价值的具体数据将取决于激励测试的最终用途。 5.2.1 从前期开始的第一次增长- 植入插入物或机加工凹口的韧性有时被描述为非预裂纹（NPC）韧性。NPC韧性可能令人感兴趣，因为它可以代表制造或加工缺陷，例如层压板中的异物碎片或加工过程中的错误。 5.2.2 下一个增长增量，从假设在第一个增量后存在的尖锐裂纹尖端开始，有时被定义为预裂纹（PC）韧性。PC韧性可能令人感兴趣，因为它更能代表对自然发生或损伤引起的分层生长的抵抗力。 5.2.3 其余的增长增量共同形成R曲线，提供了有关如何 G Ic 随着分层的进展而演变。在单向带层压板中，由于嵌套纤维在分层平面上的桥接，R曲线通常会增加，人为地增加 G Ic 对于几乎没有层间嵌套的二维编织层压板，R曲线可能是平坦的。 5.2.4 R曲线平坦的增长增量，以及 G Ic 已达到定义为的稳态值 G IR ，可能很有趣，也可能在设计和分析中有用。 5.3 本试验方法用于测量 G Ic CMC材料的用途如下: 5.3.1 定量确定CMC材料变量（纤维界面涂层、基体结构和孔隙率、纤维结构、加工和环境变量、调节/暴露处理等）的影响。 )on G Ic 以及特定CMC材料的层间裂纹扩展和损伤机制； 5.3.2 确定CMC材料是否显示R曲线行为，其中 G Ic 随着裂纹扩展而变化，或在给定的分层增长量下达到稳定值。 图2 显示了SiC-SiC复合材料的R曲线行为 ( 1. ) ; 5.3.3 为CMC损伤容限、耐久性或可靠性分析以及寿命预测制定分层失效标准和设计容许值； 注3: 只有当有信心测试产生的是材料特性，而不是结构、几何形状相关的特性时，测试数据才能可靠地用于此目的。 5.3.4 定量比较以下各项的相对值 G Ic 适用于具有不同成分和材料特性、增强结构、加工参数或环境暴露条件的不同CMC材料；和 5.3.5 定量比较以下值 G Ic 从特定CMC材料的不同批次中获得，用于进行批次验收质量控制，用作材料筛选标准，或评估批次可变性。

1.1 This test method describes the experimental methods and procedures for the determination of the critical mode I interlaminar strain energy release rate of continuous fiber- reinforced ceramic matrix composite (CMC) materials in terms of G Ic . This property is also sometimes described as the mode I fracture toughness or the mode I fracture resistance. 1.2 This test method applies primarily to ceramic matrix composite materials with a 2-D laminate structure, consisting of lay-ups of continuous ceramic fibers, in unidirectional tape or 2-D woven fabric architectures, within a brittle ceramic matrix. 1.3 This test method determines the elastic strain energy released per unit of new surface area created as a delamination grows at the interlaminar interface between two lamina or plies. The term delamination is used in this test method to specifically refer to this type of growth, while the term crack is a more general term that can also refer to matrix cracking, intralaminar delamination growth, or fiber fracture. 1.4 This test method uses a double cantilever beam (DCB) specimen to determine the critical mode I interlaminar strain energy release rate ( G Ic ). A DCB test method has been standardized for polymer matrix composites (PMCs) under Test Method D5528 . This test method addresses a similar procedure, but with modifications to account for the different physical properties, reinforcement architectures, stress-strain response, and failure mechanisms of CMCs compared to PMCs. 1.5 This test is written for ambient temperature and atmospheric test conditions, but the test method can also be used for elevated temperature or environmental exposure testing with the use of an appropriate environmental test chamber, measurement equipment for controlling and measuring the chamber temperature, humidity, and atmosphere, high temperature gripping fixtures, and modified equipment for measuring delamination growth. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6.1 Values expressed in this test method are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10 . 1.7 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. Specific hazard statements are given in Section 8 . 1.8 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 Interlaminar delamination growth can be a critical failure mode in laminated CMC structures. Knowledge of the resistance to interlaminar delamination growth of a laminated CMC is essential for material development and selection, and for CMC component design. (See ( 1- 8 ) 3 which give G Ic values of 20 J/m 2 to 800 J/m 2 for different CMC and carbon-carbon composite systems at ambient temperatures.) 5.2 Conducting this test produces multiple values of G Ic which are traditionally plotted against the delamination length at which that value was measured (see Fig. 2 ). The specific data of value to the test requestor will depend on the end use that motivated testing. 5.2.1 The first increment of growth, initiated from a pre-implanted insert or machined notch, is sometimes described as the non-precracked (NPC) toughness. NPC toughness may be of interest, as it can represent manufacturing or processing defects, such as foreign object debris in a laminate or an error during machining. 5.2.2 The next increment of growth, initiated from the sharp crack tip assumed to be present after the first increment, is sometimes defined as the precracked (PC) toughness. PC toughness may be of interest, as it is more representative of the resistance to delamination growth from a naturally occurring or damage-induced delamination. 5.2.3 The remaining increments of growth, collectively forming an R-curve, provide information on how G Ic evolves as the delamination advances. In unidirectional tape laminates, the R-curve is often increasing due to bridging of nested fibers across the delamination plane, artificially increasing G Ic . For 2-D woven laminates for which there is little interply nesting, the R-curve may be flat. 5.2.4 The increments of growth in which the R-curve is flat, and G Ic has reached a steady state value defined as G IR , may be of interest and may also useful in design and analysis. 5.3 This test method for measurement of G Ic of CMC materials can serve the following purposes: 5.3.1 To establish quantitatively the effect of CMC material variables (fiber interface coatings, matrix structure and porosity, fiber architecture, processing and environmental variables, conditioning/exposure treatments, etc.) on G Ic and the interlaminar crack growth and damage mechanisms of a particular CMC material; 5.3.2 To determine if a CMC material shows R-curve behavior where G Ic changes with crack extension or reaches a stable value at a given amount of delamination growth. Fig. 2 shows R-curve behavior for a SiC-SiC composite ( 1 ) ; 5.3.3 To develop delamination failure criteria and design allowables for CMC damage tolerance, durability or reliability analyses, and life prediction; Note 3: Test data can only reliably be used for this purpose if there is confidence that the test is yielding a material property and not a structural, geometry-dependent, property. 5.3.4 To compare quantitatively the relative values of G Ic for different CMC materials with different constituents and material properties, reinforcement architectures, processing parameters, or environmental exposure conditions; and 5.3.5 To compare quantitatively the values of G Ic obtained from different batches of a specific CMC material, to perform lot acceptance quality control, to use as a material screening criterion, or to assess batch variability.