The tensile properties of carbon fiber-reinforced plastic (CFRP)/steel laminates have been observed to exceed the expected values predicted by the rule of mixture. While the CFRP/steel laminate is expected to fail at the failure strain of the CFRP lamina, it was observed that hybridization with a steel lamina improves the failure strain. This study investigates numerically and analytically the roles of each influential mechanism responsible for this enhancement, including the thermal residual strain, bridging effect, effect of compressive transverse stress on CFRP layers, and effect of tensile transverse stress on steel layers. To assess these mechanisms, multiple finite-element and analytical models were developed. A mesoscale finite-element model was proposed, which uses novel random fiber distribution algorithm capable of reproducing random fibers with high fiber volume fractions exceeding 65%. Rather than the meso-scale model, macro finite-element models and analytical relationships were developed to assess each hybrid mechanism. Analysis showed 6% increase of the failure strain due to thermal effect and up to 11% increase of strength due to multiaxial stress in steel layer. The results of this study contribute to a deeper understanding of the role of each phenomenon that contributes to improved tensile properties in hybrid CFRP/metal laminates.

中文翻译：

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提高碳纤维增强塑料/钢混合层压板强度和断裂应变的有效机制

据观察，碳纤维增强塑料（CFRP）/钢层压板的拉伸性能超过了混合规则预测的预期值。虽然预计 CFRP/钢层压板会在 CFRP 层压板的失效应变下失效，但据观察，与钢层压板的混合可改善失效应变。本研究通过数值和分析方法研究了导致这种增强的每种影响机制的作用，包括热残余应变、桥接效应、CFRP 层上横向压应力的影响以及钢层上横向拉应力的影响。为了评估这些机制，开发了多个有限元和分析模型。提出了一种介观有限元模型，该模型采用新颖的随机纤维分布算法，能够再现纤维体积分数超过 65% 的随机纤维。开发了宏观有限元模型和分析关系来评估每种混合机制，而不是细观尺度模型。分析表明，由于热效应，失效应变增加了 6%，由于钢层中的多轴应力，强度增加了 11%。这项研究的结果有助于更深入地了解每种现象的作用，这些现象有助于提高混合 CFRP/金属层压板的拉伸性能。