面向新材料车身的粘接结构老化寿命预测方法研究

粘接是新材料车身的关键连接技术之一。胶粘剂在温度、湿度、载荷等因素的影响下，随着使用时间的增加存在老化现象，目前还没有一种有效的方法对其老化行为进行预测。本项目拟针对车身粘接结构的运行环境，提取温度、湿度、载荷三个主要因素，并根据实际运行工况分别制定循环谱，对粘接接头进行单因素及多因素耦合的加速老化试验，揭示单因素与多因素耦合作用之间的内在关系；再结合实车自然老化试验，获得粘接结构加速老化规律与实车自然老化规律之间的关系，并结合剩余强度理论与内聚力模型，初步建立一种车身粘接结构的老化寿命预测模型；在此基础上，对现有的内聚力模型进行改进，在内聚力单元中引入厚度影响，结合基于试验测试所建立的初始破坏准则，提高对较厚胶层粘接结构的预测精度、有效地预测粘接结构破坏界面的三维形态，并采用结构光法进行验证。结合上述研究内容，建立一种适用于车身粘接结构的老化寿命预测方法。

Adhesive bonding technology is one of the key connection technologies for automotive body of advanced materials. With the increase of service time, there are aging phenomena on the adhesive under the influence of temperature, humidity, load, and so on. However, so far there is still no effective method to predict the aging behaviors. Aiming at the actual operating environment of autobody adhesive structures, this project is going to extract temperature, humidity and load as the major factors, and formulate cyclic spectrums respectively to carry out single factors and multi-factor coupling accelerated aging tests for the adhesive joints so that the inherent relationship between single factors and multi-factor coupling can be revealed. And then, combining with the natural degradation tests of real vehicle running process, the relation of the accelerated aging law of adhesive structures to the natural aging law of real vehicles can be obtained. Combining the fundamental of residual strength theory with cohesive zone model together, the prediction model of aging life of autobody adhesive structures can be initially established. On the basis of the above, in order to improve the existing cohesive zone model, this project is going to introduce the influence of thickness into cohesive element, combined with the initially established failure criteria based on tests, so that the prediction accuracy for adhesive structures with thicker adhesive layers can be improved, and the three-dimension form of the adhesive structure failure interface can be predicted effectively. And it can be verified by structured light method. Combining the above research contents, a prediction method for aging life which is applicable for autobody adhesive structures is established.