A novel damage evolution model for unidirectional (UD) composites is established in this paper in the context of continuum damage mechanics (CDM). It addresses matrix cracking and it is to be applied along with the damage representation established previously. The concept of damage driving force is employed based on the Helmholtz free energy. It is shown that the damage driving force can be partitioned into three parts, resembling closely three conventional modes of fracture, respectively. A damage evolution law is derived accordingly based on the newly obtained expressions of the damage driving force. The fully rationalised Tsai-Wu criterion is employed in the model for predicting the initiation of matrix cracking damage and fibre failure, assisted with the rationalised maximum stress criterion for identifying the damage modes. A mechanism is introduced to describe the unloading behaviour as a part of the proposed model. The predictions were validated against experimental results, showing good agreement with the experiments and demonstrating the capability and effectiveness of the proposed model.

中文翻译：

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一种基于损伤驱动力概念的单向复合材料连续介质损伤演化模型


本文在连续损伤力学 （CDM） 的背景下建立了一种新的单向 （UD） 复合材料损伤演化模型。它解决了基体开裂问题，并且与之前建立的损伤表示一起应用。损伤驱动力的概念是基于亥姆霍兹自由能的。结果表明，损伤驱动力可以分为三个部分，分别类似于三种常规的断裂模式。根据新获得的损伤驱动力表达式，相应地推导出损伤演化定律。在模型中采用完全合理的 Tsai-Wu 准则来预测基体开裂损伤和纤维失效的开始，并辅以合理化的最大应力准则来识别损伤模式。引入了一种机制来描述卸载行为，作为所提出模型的一部分。预测结果与实验结果进行了验证，与实验结果吻合良好，证明了所提模型的能力和有效性。