The superior mechanical properties of ultra-thin-ply carbon fiber reinforced composites under uniaxial stress have been widely recognized. However, composite structures are often subjected to multiaxial loading in practical applications. Therefore, this study focuses on investigating the mechanical properties of ultra-thin-ply carbon fiber reinforced composites under biaxial stress conditions. Firstly, the geometric structure of a cruciform biaxial test specimen for composites is designed, and its rationality is demonstrated. Subsequently, cruciform biaxial test specimens with ply thicknesses of 24 μm and 100 μm are prepared for quasi-isotropic laminated plates, and biaxial tensile experiments with stress ratios of 0:1, 1:1, and 2:1 are conducted. This study establishes the failure envelope of ultra-thin-ply composites under biaxial tensile conditions and compare it with the experimental results of standard-ply composites. Finally, the fracture surfaces of the specimens and acoustic emission signals are analyzed to reveal the failure mechanisms of the composites under biaxial stress conditions. The results indicate that ultra-thin-ply carbon fiber reinforced composites exhibit higher interaction degree under biaxial stress, and their ability to suppress delamination is stronger.

中文翻译：

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超薄层碳纤维增强复合材料双向拉伸破坏行为研究

超薄层碳纤维增强复合材料在单轴应力下优异的力学性能已得到广泛认可。然而，复合材料结构在实际应用中经常受到多轴载荷的作用。因此，本研究重点研究超薄层碳纤维增强复合材料在双轴应力条件下的力学性能。首先设计了复合材料十字形双轴试件的几何结构，并论证了其合理性。随后，为准各向同性层合板制备了层厚为24 μm和100 μm的十字形双轴试件，并进行了应力比为0:1、1:1和2:1的双轴拉伸实验。本研究建立了超薄层复合材料在双轴拉伸条件下的失效包络线，并将其与标准层复合材料的实验结果进行比较。最后，分析样品的断裂表面和声发射信号，揭示复合材料在双轴应力条件下的失效机制。结果表明，超薄层碳纤维增强复合材料在双轴应力下表现出更高的相互作用程度，抑制分层的能力更强。