1.1 本试验方法包括在环境条件下测定具有二维蜂窝通道结构的高级陶瓷结构的弯曲强度（弯曲断裂模量）。 1.2 试验方法的重点是具有纵向空心通道（通常称为“蜂窝”通道）的工程陶瓷部件。（参见 图1 .) 组件通常有30个 % 或更大的孔隙率和蜂窝通道的横截面尺寸约为1 毫米或更大。具有这些蜂窝结构的陶瓷被广泛应用（催化转化支架 ( 1. ) , 2. 高温过滤器 ( 2. , 3. ) ，燃烧燃烧器板 ( 4. ) ，能量吸收和阻尼 ( 5. ) 等）。蜂窝陶瓷可以由多种陶瓷成分制成:氧化铝、堇青石、氧化锆、尖晶石、莫来石、碳化硅、氮化硅、石墨和碳。组件以各种几何形状（块、板、圆柱体、杆、环）生产。 L = 外跨长度（对于试验方法A， L =用户定义；对于试验方法B， L =90毫米） 注1: 4点- 1. / 4. 试验方法A1和B的荷载。 注2: 试验方法A2的3点荷载。 1.3.1 试验方法A- 具有用户定义的试样几何形状的4点或3点弯曲试验，以及 1.3.2 试验方法B- A 4点- 1. / 4. 使用规定的矩形试样几何形状（13 mm×25 mm×>116 mm）和90 mm外部支撑跨度几何形状进行点弯曲试验，适用于小孔径堇青石和碳化硅蜂窝。 1.4 试样承受破坏压力，断裂力值、试样和单元尺寸以及加载几何数据用于计算标称梁强度、壁断裂强度和蜂窝结构强度。 1.5 测试结果用于材料和结构开发、产品表征、设计数据、质量控制和工程/生产规范。 1.6 该测试方法适用于线性陶瓷材料- 张力中的弹性破坏。本试验方法不适用于以弹性或弹性延性方式失效的聚合物或金属多孔结构。 1.7 试验方法是针对环境试验温度定义的。没有提供在高温或低温下进行测试的说明。 1.8 以国际单位制表示的数值应视为标准值( IEEE/ASTM SI 10 ). 根据引用的参考文献和美国汽车行业的常见做法，本标准中很少使用英文单位来定义产品和描述工具。 1.9 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====== 5.1 本试验方法用于测定具有多个纵向空心通道（通常称为“蜂窝”通道结构）的工程陶瓷部件的弯曲力学性能。 组件通常有30个 % 或更大的孔隙率和蜂窝通道的横截面尺寸约为1 毫米或更大。 5.2 本试验方法的实验数据和计算强度值用于材料和结构开发、产品表征、设计数据、质量控制和工程/生产规范。 注1: 与压缩（压碎）试验相比，弯曲试验是确定这些部件标称“拉伸断裂”强度的首选方法。需要标称抗拉强度，因为这些材料在热梯度应力下通常会发生拉伸失效。由于夹持和对准的挑战，很难对这些蜂窝试样进行真正的拉伸试验。 5.3 本试验方法确定的机械性能取决于材料和结构，因为多孔试样的机械响应和强度是由固有材料特性和微观结构以及通道孔隙率的结构[孔隙率/相对密度、通道几何形状（形状、尺寸、细胞壁厚度等）的组合决定的。 )，各向异性和均匀性等。测试数据的比较必须考虑材料/成分特性的差异以及单个样本之间通道孔隙度结构的差异以及样本批次之间和内部的差异。 5.4 试验方法A是用户定义的试样几何形状，可选择四点或三点弯曲试验几何形状。由于蜂窝结构和蜂窝尺寸范围广泛，并且考虑了样本尺寸、蜂窝形状、间距、孔隙率大小、抗压强度和剪切强度，因此不可能为蜂窝弯曲测试定义单个固定样本几何形状。作为一般规则，实验者必须为感兴趣的特定蜂窝结构定义合适的试样几何形状，考虑成分、结构、细胞大小、机械性能和试样限制，并使用以下指南。有关试样几何形状定义的详细信息，请参见 9.2 . 5.4.1 强烈推荐使用四点弯曲（测试方法A1）进行测试和表征。（来自试验方法 C1161 第4.5节:“三点测试配置仅使试样的一小部分暴露在最大应力下。因此，三点弯曲强度可能远大于四点弯曲强度。三点弯曲具有一些优势。它使用更简单的测试夹具，更容易适应高温和断裂韧性测试，有时对焊接有帮助公牛统计研究。然而，四点弯曲是首选，并建议用于大多数表征目的。”） 5.4.2 三点弯曲试验配置（试验方法A2）可用于不适合四点试验的试样，但应清楚地认识到，与四点弯曲试验中更大的最大应力体积相比，三点加载仅使试样的一小部分暴露在最大应力下- 点加载配置。因此，基于统计缺陷分布因子，3点弯曲强度可能大于4点弯曲强度。 5.5 试验方法B（具有规定的试样尺寸和4点- 1. / 4. 点弯曲加载几何形状）广泛用于工业中的堇青石和碳化硅蜂窝结构。试验方法B是作为标准试验几何体提供的，它为具有适当特性和单元尺寸的蜂窝结构提供了基线试样尺寸，具有实验重复性、再现性和可比性。（参见 9.3 有关测试方法B.）的详细信息 注2: 为试验方法B选择了特定的夹具和试样配置，以在实际配置和线性细胞计数效应极限之间提供平衡，并允许在不需要威布尔尺寸缩放的情况下随时比较数据。 5.6 这些多孔试样中弯曲应力的计算基于小挠度弹性梁理论，假设如下: (1) 材料性质是各向同性和均匀的， (2) 拉伸和压缩的弹性模量相同，并且 (3) 该材料具有线性弹性。如果蜂窝壁中的多孔材料在微观结构上不是特定的各向异性，则也假设壁材料的微观结构是均匀和各向同性的。为了了解其中一些假设的影响，请参见Baratta等人。 ( 6. ) . 注3: 这些假设可能会限制测试在比较类型测试中的应用，例如用于材料开发、质量控制和弯曲规范。这种比较测试需要对试样几何形状和孔隙率结构以及加载几何形状、应变率和大气/测试条件的实验条件进行一致和标准化的测试。 5.7 三个弯曲强度值（在第节中定义 3. 并在截面中计算 11 )可在本试验方法中计算。 它们是标称梁强度、壁断裂强度和蜂窝结构强度。 5.7.1 标称梁强度- 计算弯曲强度的第一种方法是简化假设，即试样作为均匀均匀材料，作为连续介质反应。基于这些假设，标称梁强度 S NB公司 可以使用标准弯曲强度方程以及试样尺寸和断裂力来计算。（参见第节 11 .) 5.7.1.1 在研究陶瓷蜂窝试样的弯曲强度时，注意到了线性单元数效应（试样尺寸单元数效应） ( 7. , 8. ) . 如果相对于试样尺寸而言，晶胞尺寸过大，并且线性晶胞数（沿最短横截面尺寸的晶胞整数）太低（<15），则通道孔隙率会对惯性矩产生几何影响，从而产生人为高的标称梁强度值。 （参见 附录X1 .) 由于计算中未考虑开孔结构的真实惯性矩，因此使用标准弹性梁方程高估了强度值。 5.7.1.2 对于线性细胞计数较低的样本，这种高估值越来越大。对于计算的标称梁强度，线性单元数必须大于等于15， S NB公司 ，在10以内 % 高估墙体断裂强度 S WF公司 . 注4: 韦伯、维贾亚和海尔芬斯汀的研究 ( 7. ) 结果表明，对于具有方形横截面的单元，应保持15的最小线性单元数，以最小化线性单元数对计算标称梁强度的影响。（本研究总结见 附录X1 .) 5.7.1.3 对于较小的试样（其中线性单元数在2到15之间），第节给出了壁断裂强度和蜂窝结构强度的方程 11 . 与计算的标称梁强度相比，这些方程用于计算更精确的蜂窝弯曲强度值。 5.7.2 壁断裂强度，S WF公司 , 根据蜂窝结构中通道的几何形状、尺寸、细胞壁厚和线性计数，使用蜂窝结构的真实惯性矩计算。壁断裂强度是对试样外纤维表面真实破坏应力的计算。( 附录X1 描述了Webb、Widjaja和Helfinstine中引用的计算 ( 7. ) 报告）。部分 11 在计算中，给出了方形蜂窝通道和均匀细胞壁厚试样的惯性矩计算公式。 注5: 第节中给出的惯性矩公式 11 和 附录X1 仅适用于方形单元几何形状。它不适用于矩形、圆形、六角形或三角形几何形状。这些几何形状的公式必须根据几何分析和第一原理推导。 5.7.3 蜂窝结构强度，S HS , 根据墙体断裂强度计算 S WF公司 . 该计算给出了一个弯曲强度值，该值与试样单元尺寸几何效应无关。蜂窝结构强度值可用于比较不同通道尺寸的不同试样几何形状。它还提供了可用于假设连续强度的应力模型的弯曲强度值。（参见 附录X1 .) 部分 11 计算中给出了方形蜂窝通道和均匀蜂窝壁厚试样的蜂窝结构强度计算公式。 5.7.4 以下建议用于计算陶瓷蜂窝试样的弯曲强度。 5.7.4.1 对于弯曲试样 其中线性单元格计数为15或更大 ，标称梁强度 S NB公司 蜂窝结构强度计算 S HS 值大致相等（10以内 %). 标称梁强度 S NB公司 考虑到这种可变性，可以使用计算。 5.7.4.2 对于弯曲试样 其中，线性单元格计数在5到15之间 ，标称梁强度 S NB公司 计算结果可能为10到20 % 价值过高。这个 S NB公司 应谨慎使用该值。 5.7.4.3 对于弯曲试样 其中线性单元格计数小于5 ，标称梁强度 S NB公司 计算结果可能为20到100 % 价值过高。建议蜂窝结构强度 S HS 计算并用作更准确的弯曲强度值。 5.7.4.4 如果试样可用性和试验配置允许，最好使用线性单元数为15或更大的试样，以减少试样线性单元数对标称梁强度的影响 S NB公司 小于10 %. 5.8 多孔陶瓷的弯曲试验数据将具有统计分布，根据实践，可通过威布尔统计进行分析和描述 C1239 . 5.9 该弯曲试验可以用作表征工具，以评估制造变量、几何形状和微观结构变化以及环境暴露对蜂窝机械性能的影响。 这些变量的影响是通过在基线条件下对一组试样进行弯曲测试来评估的，然后对第二组试样进行测试，这些试样的几何形状或制造方法发生了定义的变化，或者在受控环境暴露后进行了测试。 5.9.1 几何形状和微观结构变化包括细胞几何形状（形状尺寸、细胞壁厚度和计数）和细胞壁孔隙度（百分比、大小、形状、形态等）的变化。 5.9.2 制造工艺变化包括成型参数、干燥和粘合剂烧坏条件、烧结条件、热处理、涂层变化等。 5.9.3 环境调节包括在不同温度和不同腐蚀性大气（包括蒸汽）下的长期暴露。 5.10 该弯曲试验可用于评估蜂窝陶瓷的抗热震性，如试验方法所述 C1525 . 5.11 弯曲试验不是测定这些多孔结构杨氏模量的首选方法。 （因此，本试验中通常不测量弯曲试棒的挠度。）声共振杨氏模量测量（试验方法 C1198 )或通过冲击激励（试验方法 C1259 )提供更可靠和可重复的数据。 5.12 目前要求进行断口分析超出了本标准的范围。多孔蜂窝陶瓷中关键缺陷的断口分析极其困难，且具有非常不确定的价值。

1.1 This test method covers the determination of the flexural strength (modulus of rupture in bending) at ambient conditions of advanced ceramic structures with 2-dimensional honeycomb channel architectures. 1.2 The test method is focused on engineered ceramic components with longitudinal hollow channels, commonly called “honeycomb” channels. (See Fig. 1 .) The components generally have 30 % or more porosity and the cross-sectional dimensions of the honeycomb channels are on the order of 1 mm or greater. Ceramics with these honeycomb structures are used in a wide range of applications (catalytic conversion supports ( 1 ) , 2 high temperature filters ( 2 , 3 ) , combustion burner plates ( 4 ) , energy absorption and damping ( 5 ) , etc.). The honeycomb ceramics can be made in a range of ceramic compositions—alumina, cordierite, zirconia, spinel, mullite, silicon carbide, silicon nitride, graphite, and carbon. The components are produced in a variety of geometries (blocks, plates, cylinders, rods, rings). L = Outer Span Length (for Test Method A, L = User defined; for Test Method B, L = 90 mm) Note 1: 4-Point- 1 / 4 Loading for Test Methods A1 and B. Note 2: 3-Point Loading for Test Method A2. 1.3.1 Test Method A— A 4-point or 3-point bending test with user-defined specimen geometries, and 1.3.2 Test Method B— A 4-point- 1 / 4 point bending test with a defined rectangular specimen geometry (13 mm × 25 mm × > 116 mm) and a 90 mm outer support span geometry suitable for cordierite and silicon carbide honeycombs with small cell sizes. 1.4 The test specimens are stressed to failure and the breaking force value, specimen and cell dimensions, and loading geometry data are used to calculate a nominal beam strength, a wall fracture strength, and a honeycomb structure strength. 1.5 Test results are used for material and structural development, product characterization, design data, quality control, and engineering/production specifications. 1.6 The test method is meant for ceramic materials that are linear-elastic to failure in tension. The test method is not applicable to polymer or metallic porous structures that fail in an elastomeric or an elastic-ductile manner. 1.7 The test method is defined for ambient testing temperatures. No directions are provided for testing at elevated or cryogenic temperatures. 1.8 The values stated in SI units are to be regarded as standard ( IEEE/ASTM SI 10 ). English units are sparsely used in this standard for product definitions and tool descriptions, per the cited references and common practice in the US automotive industry. 1.9 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 ====== 5.1 This test method is used to determine the mechanical properties in flexure of engineered ceramic components with multiple longitudinal hollow channels, commonly described as “honeycomb” channel architectures. The components generally have 30 % or more porosity and the cross-sectional dimensions of the honeycomb channels are on the order of 1 mm or greater. 5.2 The experimental data and calculated strength values from this test method are used for material and structural development, product characterization, design data, quality control, and engineering/production specifications. Note 1: Flexure testing is the preferred method for determining the nominal “tensile fracture” strength of these components, as compared to a compression (crushing) test. A nominal tensile strength is required, because these materials commonly fail in tension under thermal gradient stresses. A true tensile test is difficult to perform on these honeycomb specimens because of gripping and alignment challenges. 5.3 The mechanical properties determined by this test method are both material and architecture dependent, because the mechanical response and strength of the porous test specimens are determined by a combination of inherent material properties and microstructure and the architecture of the channel porosity [porosity fraction/relative density, channel geometry (shape, dimensions, cell wall thickness, etc.), anisotropy and uniformity, etc.] in the specimen. Comparison of test data must consider both differences in material/composition properties as well as differences in channel porosity architecture between individual specimens and differences between and within specimen lots. 5.4 Test Method A is a user-defined specimen geometry with a choice of four-point or three-point flexure testing geometries. It is not possible to define a single fixed specimen geometry for flexure testing of honeycombs, because of the wide range of honeycomb architectures and cell sizes and considerations of specimen size, cell shapes, pitch, porosity size, crush strength, and shear strength. As a general rule, the experimenter will have to define a suitable test specimen geometry for the particular honeycomb structure of interest, considering composition, architecture, cell size, mechanical properties, and specimen limitations and using the following guidelines. Details on specimen geometry definition are given in 9.2 . 5.4.1 Four-point flexure (Test Method A1) is strongly preferred and recommended for testing and characterization purposes. (From Test Method C1161 section 4.5: “The three-point test configuration exposes only a very small portion of the specimen to the maximum stress. Therefore, three-point flexural strengths are likely to be much greater than four-point flexural strengths. Three-point flexure has some advantages. It uses simpler test fixtures, it is easier to adapt to high temperature and fracture toughness testing, and it is sometimes helpful in Weibull statistical studies. However, four-point flexure is preferred and recommended for most characterization purposes.”) 5.4.2 The three-point flexure test configuration (Test Method A2) may be used for specimens which are not suitable for 4-point testing, with the clear understanding that 3-point loading exposes only a very small portion of the specimen to the maximum stress, as compared to the much larger maximum stress volume in a 4-point loading configuration. Therefore, 3-point flexural strengths are likely to be greater than 4-point flexural strengths, based on statistical flaw distribution factors. 5.5 Test Method B (with a specified specimen size and a 4-point- 1 / 4 point flexure loading geometry) is widely used in industry for cordierite and silicon carbide honeycomb structures with small cell size (cell pitch ~2 mm). Test Method B is provided as a standard test geometry that provides a baseline specimen size for honeycomb structures with appropriate properties and cell size with the benefit of experimental repeatability, reproducibility and comparability. (See 9.3 for details on Test Method B.) Note 2: Specific fixture and specimen configurations were chosen for Test Method B to provide a balance between practical configurations and linear cell count effect limits and to permit ready comparison of data without the need for Weibull-size scaling. 5.6 The calculation of the flexure stress in these porous specimens is based on small deflection elastic beam theory with assumptions that (1) the material properties are isotropic and homogeneous, (2) the moduli of elasticity in tension and compression are identical, and (3) the material is linearly elastic. If the porous material in the walls of the honeycomb is not specifically anisotropic in microstructure, it is also assumed that the microstructure of the wall material is uniform and isotropic. To understand the effects of some of these assumptions, see Baratta et al. ( 6 ) . Note 3: These assumptions may limit the application of the test to comparative type testing such as used for material development, quality control, and flexure specifications. Such comparative testing requires consistent and standardized test conditions both for specimen geometry and porosity architecture, as well as experimental conditions—loading geometries, strain rates, and atmospheric/test conditions. 5.7 Three flexure strength values (defined in Section 3 and calculated in Section 11 ) may be calculated in this test method. They are the nominal beam strength, the wall fracture strength, and the honeycomb structure strength. 5.7.1 Nominal Beam Strength— The first approach to calculating a flexure strength is to make the simplifying assumption that the specimen acts as a uniform homogeneous material that reacts as a continuum. Based on these assumptions, a nominal beam strength S NB can be calculated using the standard flexure strength equations with the specimen dimensions and the breaking force. (See Section 11 .) 5.7.1.1 A linear cell count effect (specimen size-cell count effect) has been noted in research on the flexure strength of ceramic honeycomb test specimens ( 7 , 8 ) . If the cell size is too large with respect to the specimen dimensions and if the linear cell count (the integer number of cells along the shortest cross-sectional dimension) is too low (<15), channel porosity has a geometric effect on the moment of inertia that produces an artificially high value for the nominal beam strength. (See Appendix X1 .) With the standard elastic beam equations the strength value is overestimated, because the true moment of inertia of the open cell structure is not accounted for in the calculation. 5.7.1.2 This overestimate becomes increasingly larger for specimens with lower linear cell counts. The linear cell count has to be 15 or greater for the calculated nominal beam strength, S NB , to be within a 10 % overestimate of the wall fracture strength S WF . Note 4: The study by Webb, Widjaja, and Helfinstine ( 7 ) showed that for cells with a square cross section a minimum linear cell count of 15 should be maintained to minimize linear cell count effects on the calculated nominal beam strength. (This study is summarized in Appendix X1 .) 5.7.1.3 For those smaller test specimens (where the linear cell count is between 2 and 15), equations for wall fracture strength and honeycomb structure strength are given in Section 11 . These equations are used to calculate a more accurate value for the flexure strength of the honeycomb, as compared to the calculated nominal beam strength. 5.7.2 Wall Fracture Strength, S WF , is calculated using the true moment of inertia of the honeycomb architecture, based on the geometry, dimensions, cell wall thickness, and linear count of the channels in the honeycomb structure. The wall fracture strength is a calculation of the true failure stress in the outer fiber surface of the specimen. ( Appendix X1 describes the calculation as cited in the Webb, Widjaja, and Helfinstine ( 7 ) report). Section 11 on calculations gives the formula for calculating the moment of inertia for test specimens with square honeycomb channels and uniform cell wall thickness. Note 5: The moment of inertia formula given in Section 11 and Appendix X1 is only applicable to square cell geometries. It is not suitable for rectangular, circular, hexagonal, or triangular geometries. Formulas for those geometries have to be developed from geometric analysis and first principles. 5.7.3 Honeycomb Structure Strength, S HS , is calculated from the wall fracture strength S WF . This calculation gives a flexure strength value which is independent of specimen-cell size geometry effects. The honeycomb structure strength value can be used for comparison of different specimen geometries with different channel sizes. It also gives a flexure strength value that can be used for stress models that assume continuum strength. (See Appendix X1 .) Section 11 on calculations gives the formula for calculating the honeycomb structure strength for test specimens with square honeycomb channels and uniform cell wall thickness. 5.7.4 The following recommendations are made for calculating a flexure strength for the ceramic honeycomb test specimens. 5.7.4.1 For flexure test specimens where the linear cell count is 15 or greater , the nominal beam strength S NB calculation and the honeycomb structure strength S HS are roughly equivalent in value (within 10 %). The nominal beam strength S NB calculation can be used considering this variability. 5.7.4.2 For flexure test specimens where the linear cell count is between 5 and 15 , the nominal beam strength S NB calculation may produce a 10 to 20 % overvalue. The S NB value should be used with caution. 5.7.4.3 For flexure test specimens where the linear cell count is less than 5 , the nominal beam strength S NB calculation may produce a 20 to 100 % overvalue. It is recommended that the honeycomb structure strength S HS be calculated and used as a more accurate flexure strength number. 5.7.4.4 If specimen availability and test configuration permit, test specimens with a linear cell count of 15 or greater are preferred to reduce the specimen linear cell count effect on nominal beam strength S NB to less than 10 %. 5.8 Flexure test data for porous ceramics will have a statistical distribution, which may be analyzed and described by Weibull statistics, per Practice C1239 . 5.9 This flexure test can be used as a characterization tool to assess the effects of fabrication variables, geometry and microstructure variations, and environmental exposure on the mechanical properties of the honeycombs. The effect of these variables is assessed by flexure testing a specimen set in a baseline condition and then testing a second set of specimens with defined changes in geometry or fabrication methods or after controlled environmental exposure. 5.9.1 Geometry and microstructure variations would include variations in cell geometry (shape dimensions, cell wall thickness, and count) and wall porosity (percent, size, shape, morphology, etc.). 5.9.2 Fabrication process variations would include forming parameters, drying and binder burn-out conditions, sintering conditions, heat treatments, variations in coatings, etc. 5.9.3 Environmental conditioning would include extended exposure at different temperatures and different corrosive atmospheres (including steam). 5.10 This flexure test may be used to assess the thermal shock resistance of the honeycomb ceramics, as described in Test Method C1525 . 5.11 The flexure test is not the preferred method for determining the Young's modulus of these porous structures. (For this reason, the deflection of the flexure test bar is not commonly measured in this test.) Young's modulus measurements by sonic resonance (Test Method C1198 ) or by impulse excitation (Test Method C1259 ) give more reliable and repeatable data. 5.12 It is beyond the scope of this standard to require fractographic analysis at the present time. Fractographic analysis for critical flaws in porous honeycomb ceramics is extremely difficult and of very uncertain value.