ABSTRACT The effect of elastic and thermal mismatches between fiber and matrix on the push-in mechanism and interfacial shear strength ( ) measurement of typical polymer and ceramic matrix composites was studied in this work by comprehensive finite element modeling of push-in response, using carbon fiber-reinforced epoxy and SiC matrix (Cf/epoxy and Cf/SiC) as model materials. The results highlight a strong effect of fiber-localized environment on the push-in response, especially for the Cf/epoxy with large elastic mismatch. This led to errors to estimate if applying directly the standard shear-lag model to calculate τ0 according to the push-in response. Calibrations of the shear-lag model were thus performed in both Cf/epoxy and Cf/SiC, and the results suggest a negligible effect of the elastic mismatch in the Cf/SiC due to the comparable elastic properties between fiber and matrix. The shear-lag model can thus well estimate based on the push-in force–displacement curves. If the residual thermal stress was considered, the push-in deformation was altered by increasing evidently the critical load leading to interfacial fracture, which led to overestimation of . This is a consequence of the large shear stress level concentrated mainly at the fiber/matrix interface. Detailed parametric push-in simulations were afterwards performed to incorporate the effect of interfacial shear stress in the standard shear-lag model, and a more proper shear-lag model calibrated by incorporating both elastic and thermal mismatches was finally proposed.

中文翻译：

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弹性和热失配对纤维/基体界面推入机制和剪切强度测量的影响

摘要 本工作通过推入响应的综合有限元建模，研究了纤维和基体之间的弹性和热失配对典型聚合物和陶瓷基复合材料的推入机制和界面剪切强度 ( ) 测量的影响，使用碳纤维增强环氧树脂和 SiC 基体（Cf/环氧树脂和 Cf/SiC）作为模型材料。结果突出了纤维局部环境对推入响应的强烈影响，特别是对于具有较大弹性失配的 Cf/环氧树脂。这导致错误估计是否直接应用标准剪切滞后模型根据推入响应计算 τ0。因此，在 Cf/环氧树脂和 Cf/SiC 中进行了剪切滞后模型的校准，结果表明，由于纤维和基体之间的弹性性能相当，Cf/SiC 中弹性失配的影响可以忽略不计。因此，剪切滞后模型可以根据推入力 - 位移曲线很好地估计。如果考虑残余热应力，推入变形会通过明显增加导致界面断裂的临界载荷而改变，从而导致对 的高估。这是主要集中在纤维/基体界面处的大剪切应力水平的结果。随后进行了详细的参数推入模拟，以将界面剪应力的影响纳入标准剪切滞后模型，并最终提出了通过结合弹性和热失配校准的更合适的剪切滞后模型。因此，剪切滞后模型可以根据推入力 - 位移曲线很好地估计。如果考虑残余热应力，推入变形会通过明显增加导致界面断裂的临界载荷而改变，从而导致对 的高估。这是主要集中在纤维/基体界面处的大剪切应力水平的结果。随后进行了详细的参数推入模拟，以将界面剪应力的影响纳入标准剪切滞后模型，并最终提出了通过结合弹性和热失配校准的更合适的剪切滞后模型。因此，剪切滞后模型可以根据推入力 - 位移曲线很好地估计。如果考虑残余热应力，推入变形会通过明显增加导致界面断裂的临界载荷而改变，从而导致对 的高估。这是主要集中在纤维/基体界面处的大剪切应力水平的结果。随后进行了详细的参数推入模拟，以将界面剪应力的影响纳入标准剪切滞后模型，并最终提出了通过结合弹性和热失配校准的更合适的剪切滞后模型。推入变形通过明显增加导致界面断裂的临界载荷而改变，这导致 . 这是主要集中在纤维/基体界面处的大剪切应力水平的结果。随后进行了详细的参数推入模拟，以将界面剪应力的影响纳入标准剪切滞后模型，并最终提出了通过结合弹性和热失配校准的更合适的剪切滞后模型。推入变形通过明显增加导致界面断裂的临界载荷而改变，这导致 . 这是主要集中在纤维/基体界面处的大剪切应力水平的结果。随后进行了详细的参数推入模拟，以将界面剪应力的影响纳入标准剪切滞后模型，并最终提出了通过结合弹性和热失配校准的更合适的剪切滞后模型。