ASTM C1819-15
使用彈性襯墊在環境溫度下測定連續纖維增強型高級陶瓷復合管試件的環向拉伸強度的標準試驗方法

Standard Test Method for Hoop Tensile Strength of Continuous Fiber-Reinforced Advanced Ceramic Composite Tubular Test Specimens at Ambient Temperature Using Elastomeric Inserts

被代替

標準號

ASTM C1819-15

發布

2015年

發布單位

美國材料與試驗協會

替代標準

ASTM C1819-21

當前最新

ASTM C1819-21

 

 

引用標準

ASTM C1145 ASTM C1239 ASTM D3878 ASTM E1012 ASTM E177 ASTM E337 ASTM E380 ASTM E4 ASTM E6 ASTM E691 ASTM E83

適用范圍

5.1 This test method (a.k.a., overhung tube method) may be used for material development, material comparison, material screening, material down selection and quality assurance. This test method is not recommended for material characterization, design data generation and/or material model verification/validation.

5.2 Continuous fiber-reinforced ceramic composites (CFCC) are composed of continuous ceramic-fiber directional (1-D, 2-D, and 3-D) reinforcements in a fine grain-sized (<50 µm) ceramic matrix with controlled porosity. Often these composites have an engineered thin (0.1 to 10 µm) interface coating on the fibers to produce crack deflection and fiber pull-out.

5.3 CFCC components have a distinctive and synergistic combination of material properties, interface coatings, porosity control, composite architecture (1-D, 2-D, and 3-D), and geometric shape that are generally inseparable. Prediction of the mechanical performance of CFCC tubes (particularly with braid and 3-D weave architectures) cannot be made by applying measured properties from flat CFCC plates to the design of tubes. In particular tubular components comprised of CMCs material form a unique synergistic combination of material and geometric shape that are generally inseparable. In other words, prediction of mechanical performance of CMC tubes generally cannot be made by using properties measured from flat plates. Strength tests of internally-pressurized, CMC tubes provide information on mechanical behavior and strength for a multiaxially-stressed material.

5.4 Unlike monolithic advanced ceramics which fracture catastrophically from a single dominant flaw, CMCs generally experience “graceful” fracture from a cumulative damage process. Therefore, while the volume of material subjected to a uniform hoop tensile stress for a single uniformly pressurized tube test may be a significant factor for determining matrix cracking stress, this same volume may not be as significant a factor in determining the ultimate strength of a CMC. However, the probabilistic nature of the strength distributions of the brittle matrices of CMCs requires a statistically significant number of test specimens for statistical analysis and design. Studies to determine the exact influence of test specimen volume on strength distributions for CMCs have not been completed. It should be noted that hoop tensile strengths obtained using different recommended test specimens with different volumes of material in the gage sections may be different due to these volume effects.

5.5 Hoop tensile strength tests provide information on the strength and deformation of materials under biaxial stresses induced from internal pressurization of tubes. Non-uniform stress states are inherent in these types of tests and subsequent evaluation of any non-linear stress-strain behavior must take into account the unsymmetric behavior of the CMC under biaxial stressing. This non-linear behavior which may develop as the result of cumulative damage processes (for example, matrix cracking, matrix/fiber debonding, fiber fracture, delamination, etc.) which may be influenced by testing mode, testing rate, processing or alloying effects, or environmental influences. Some of these effects may be consequences of stress corrosion or subcritical (slow) crack growth that can be minimized by testing at sufficiently rapid rates as outlined in this test method.

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