The stiffness degradation represents one of the most interesting damage phenomena used for describing the fatigue behaviour of composites. A critical aspect of modelling the damage is represented by the simulation of the whole behaviour of the composite and by the assessment of the actual stiffness for the models validation. In this work, the stiffness degradation of quasi‐isotropic carbon fibre reinforced polymer (CFRP) obtained by automated fibre placement has been assessed by means of thermoelastic stress analysis. The amplitude of temperature signal at the mechanical frequency (thermoelastic signal) was considered as an indicator of material degradation and compared with the data provided by an extensometer. The correlation between thermoelastic and mechanical data allowed to build a new experimental model for evaluating and predicting material stiffness degradation by just using thermoelastic data. The proposed approach seems to be very promising for stiffness degradation assessment of real and complex mechanical components subjected to actual loading conditions.

中文翻译：

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使用热弹性应力分析评估复合材料的损伤：一种评估刚度退化的有前途的技术

刚度下降代表了用于描述复合材料疲劳行为的最有趣的破坏现象之一。对损伤进行建模的一个关键方面是对复合材料的整体行为进行仿真，并通过对模型验证的实际刚度进行评估。在这项工作中，通过热弹性应力分析评估了通过自动纤维铺放获得的准各向同性碳纤维增强聚合物（CFRP）的刚度退化。机械频率下的温度信号幅度（热弹性信号）被认为是材料降解的指标，并与引伸计提供的数据进行了比较。热弹性和力学数据之间的相关性允许建立一个新的实验模型，仅通过使用热弹性数据就可以评估和预测材料的刚度退化。对于实际和复杂机械部件在实际载荷条件下的刚度退化评估，提出的方法似乎很有希望。