Abstract Stress redistribution and damage phenomena in the vicinity of the first-fibre break in unidirectional composites under longitudinal tensile loads are investigated by means of high-fidelity computational micromechanics based on experimentally characterised material constituents. In this framework, periodic microstructures with statistically representative random fibre packings are analysed, and transient dynamic analyses are performed to take into account the progressive failure and recoiling of a breaking fibre. The effects of mechanisms such as curing residual stresses, fibre/matrix debonding and matrix inelastic deformation on the first-fibre failure process are investigated. The stress concentration factors on intact fibres are found to depend on the statistical failure stress of the breaking fibres, and decrease with increasing strength. For the AS4/8552 composite with average constituent properties, maximum stress concentration factors of 20.6%, 16.1% and 14.2% are predicted, respectively, for fibre volume fractions of 50%, 60%, 70%. Material systems with lower fibre-to-matrix stiffness ratios, such as glass/epoxy, result in lower stress concentration factors. The fibre/matrix interface strength is found to have a limited overall influence on stress redistribution around fibre breakage.

中文翻译：

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单向复合材料中第一纤维破坏的高保真计算微观力学：变形机制和应力集中因素

摘要 通过基于实验表征的材料成分的高保真计算微观力学研究了在纵向拉伸载荷下单向复合材料中第一纤维断裂附近的应力重新分布和损伤现象。在此框架中，分析具有统计代表性随机纤维堆积的周期性微观结构，并进行瞬态动态分析以考虑断裂纤维的渐进失效和反卷。研究了固化残余应力、纤维/基体脱粘和基体非弹性变形等机制对第一纤维破坏过程的影响。发现完整纤维上的应力集中因子取决于断裂纤维的统计失效应力，并随着强度的增加而减少。对于具有平均成分特性的 AS4/8552 复合材料，对于 50%、60%、70% 的纤维体积分数，预计最大应力集中系数分别为 20.6%、16.1% 和 14.2%。具有较低纤维与基体刚度比的材料系统，例如玻璃/环氧树脂，会导致较低的应力集中系数。发现纤维/基质界面强度对纤维断裂周围应力重新分布的总体影响有限。