Li Huaguan, Wang Hao, Xiang Junxian, Li Zhaoxuan, Chen Xi, Tao Jie
Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing Institute of Technology, Nanjing 211167, China.
College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.
Polymers (Basel). 2022 May 12;14(10):1982. doi: 10.3390/polym14101982.
Nowadays, variable preparation, forming and processing methods of fiber metal laminates are constantly developing to meet the requirements of different application fields, hence the characteristics and evolution of residual stresses under different manufacturing conditions deserve more attention. In this work, the evolution behaviors of curing residual stresses in GLARE under a hot-pressing condition were studied, and the residual stress reduction mechanism was also explained. Results suggested the FE prediction models of the entire cure process, verified by the fiber Bragg grating (FBG) sensors, were more precise than the traditional elastic model. Moreover, the stress evolution during the cure process mainly occurred in the cooling stage, in which the different coefficient of thermal expansion (CTE) of aluminum and GFRP played a major role. Meanwhile, curing shrinkage stress in the GFRP layer during the holding stage at curing temperature obviously influenced the final stress level. The residual stresses in GFRP layers differed by 9.6 MPa under a hot-pressing and autoclave condition, in which the convection heat transfer condition played a major role as it caused lower thermal stress in the holding stage and a smaller temperature gradient in the cooling stage. Considering this, a lower cooling rate could be a feasible way to obtain GLARE with lower residual stress under a hot-pressing condition.
如今，纤维金属层压板的制备、成型和加工方法不断发展，以满足不同应用领域的需求，因此不同制造条件下残余应力的特性和演变值得更多关注。在这项工作中，研究了热压条件下GLARE固化残余应力的演变行为，并解释了残余应力降低机制。结果表明，经光纤布拉格光栅（FBG）传感器验证的整个固化过程的有限元预测模型比传统弹性模型更精确。此外，固化过程中的应力演变主要发生在冷却阶段，其中铝和玻璃纤维增强塑料（GFRP）不同的热膨胀系数（CTE）起主要作用。同时，在固化温度下保温阶段GFRP层中的固化收缩应力明显影响最终应力水平。在热压和高压釜条件下，GFRP层中的残余应力相差9.6MPa，其中对流换热条件起主要作用，因为它在保温阶段导致较低的热应力，在冷却阶段导致较小的温度梯度。考虑到这一点，较低的冷却速率可能是在热压条件下获得具有较低残余应力的GLARE的可行方法。
