Experimental Study on Flexural Properties of FRP Foam Sandwich Plates in Hot and Humid Environment

In this paper, the fiber-reinforced foam sandwich composites were prepared by Vacuum-Assisted Resin Injection (VARI). Then the damp heat aging experiment was carried out on the specimens using a constant temperature and humidity test chamber and the bending property of the treated specimens was investigated using the universal testing machine. Finally, the microstructural analysis of scanning electron microscopy (SEM) technique was utilized for damage mechanism analysis. The results show that the mechanical properties of the specimens decrease after the damp heat aging, and the unidirectional laminated fibers have better resistance to the hot and humid environment than the orthogonal laminated fibers. The setting of drainage holes can increase the resistance of the specimens to the hot and humid environment, and the mixed fibers reduce the residual mechanical properties of the fiber-reinforced foam sandwich composites after the damp heat aging. These findings provide guiding insights for the future design and fabrication of more durable composite materials. Moreover, they are of significance to improve the material performance, extend its service life, and expand its range of applications.