In the present study, a novel methodology of damage modeling is introduced to predict damage propagation in fibrous composite materials according to the plastic strain energy density induced in the lamina only. The importance of the new damage-model is the ability to assess damage-evolution in fibrous composite laminae irrespective of stress-state and fiber-orientation angle. An energy-based model called as a unified damage model, is proposed to evaluate damage in unidirectional fibrous composite laminae. The aforementioned damage model represents a unique relationship between damage-evolution and the resulting plastic strain energy density induced in the composite lamina, as verified through this study. Damage propagation under a state of in-plane-stress is investigated for three composite laminas; boron/epoxy, graphite/epoxy, and carbon/epoxy. The unified damage model represents a simplified mathematical relation of quantum-damage (or modified-damage) variables in terms of the induced plastic-strain-energy density induced in a composite lamina. The developed unified damage model confirms the results of Ghazi-Ahmad macro-mechanical damage model in which graphite/epoxy has the lowest damage response, whereas boron/epoxy has the highest possible damage response amongst the three composite materials. Also, it is noticed that quantum-damage propagates nonlinearly with the evolved plastic strain energy density in fibrous composite laminae.

中文翻译：

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受面内应力状态和多材料非线性影响的纤维复合薄板的统一损伤模型

在本研究中，引入了一种新的损伤建模方法，仅根据在薄层中引起的塑性应变能量密度来预测纤维复合材料中的损伤传播。新损伤模型的重要性在于能够评估纤维复合薄层中的损伤演化，而与应力状态和纤维取向角无关。提出了一种称为统一损伤模型的基于能量的模型来评估单向纤维复合薄层中的损伤。上述损伤模型代表了损伤演化与复合材料薄层中引起的塑性应变能量密度之间的独特关系，如本研究所证实的那样。研究了三个复合材料薄片在面内应力状态下的损伤传播；硼/环氧树脂、石墨/环氧树脂和碳/环氧树脂。统一损伤模型表示量子损伤（或修正损伤）变量在复合材料薄层中诱导的塑性应变能量密度方面的简化数学关系。开发的统一损伤模型证实了 Ghazi-Ahmad 宏观机械损伤模型的结果，其中石墨/环氧树脂具有最低的损伤响应，而硼/环氧树脂在三种复合材料中具有最高的可能损伤响应。此外，还注意到量子损伤随着纤维复合薄层中演化的塑性应变能量密度非线性传播。开发的统一损伤模型证实了 Ghazi-Ahmad 宏观力学损伤模型的结果，其中石墨/环氧树脂具有最低的损伤响应，而硼/环氧树脂在三种复合材料中具有最高的可能损伤响应。此外，还注意到量子损伤随着纤维复合薄层中演化的塑性应变能量密度非线性传播。开发的统一损伤模型证实了 Ghazi-Ahmad 宏观机械损伤模型的结果，其中石墨/环氧树脂具有最低的损伤响应，而硼/环氧树脂在三种复合材料中具有最高的可能损伤响应。此外，还注意到量子损伤随着纤维复合薄层中演化的塑性应变能量密度非线性传播。