Background

Accurate evaluation of life-limiting failure behavior is a prerequisite to ensure the successful design and application of ceramic matrix composites (CMCs).

Objective

To investigate life-limiting failure behavior of CMCs, it is necessary to evaluate the in-plane shear strength.

Methods

In this paper, the in-plane shear strength (IPSS) of two-dimensional carbon fiber reinforced silicon carbide matrix (2D C/SiC) composites at elevated temperatures in air was studied by a modified Iosipescu method. A simplified Iosipescu loading configuration without mechanical connections or a fastening assembly was proposed.

Results

According to finite element analysis, an almost pure in-plane shear stress field and an in-plane shear failure mode were obtained. The modified Iosipescu method was adopted to evaluate the IPSS of 2D C/SiC at room temperature (RT), 800 °C, and 1000 °C. The in-plane shear failure mode was observed, and the IPSSs were obtained. Based on the microstructure analysis, the release of the tensile stress at elevated temperatures can account for the increase in the IPSS from RT to 800 °C. The decrease in the IPSS from 800 °C to 1000 °C may have resulted from the oxidation of carbon fibers.

Conclusions

The modified Iosipescu method can be used to measure the in-plane properties of CMCs. This study may be beneficial to reveal the failure mechanisms and guide the design of CMCs.

中文翻译：

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一种改进的 Iosipescu 方法研究 C/SiC 复合材料在高温空气中的面内剪切强度

背景

准确评估限寿失效行为是确保陶瓷基复合材料 (CMC) 成功设计和应用的先决条件。

客观的

为了研究 CMC 的寿命限制失效行为，有必要评估面内剪切强度。

方法

在本文中，通过改进的 Iosipescu 方法研究了二维碳纤维增强碳化硅基 (2D C/SiC) 复合材料在空气中高温下的面内剪切强度 (IPSS)。提出了一种没有机械连接或紧固组件的简化 Iosipescu 加载配置。

结果

根据有限元分析，获得了几乎纯的面内剪切应力场和面内剪切破坏模式。采用改进的 Iosipescu 方法在室温 (RT)、800 °C 和 1000 °C 下评估 2D C/SiC 的 IPSS。观察面内剪切破坏模式，得到IPSSs。根据微观结构分析，高温下拉伸应力的释放可以解释 IPSS 从 RT 增加到 800 °C。IPSS 从 800 °C 下降到 1000 °C 可能是碳纤维氧化的结果。

结论

改进的 Iosipescu 方法可用于测量 CMC 的面内特性。该研究可能有助于揭示失效机制并指导 CMC 的设计。