高低温交变湿热环境下外加载荷对不同孔隙率CFRP拉伸力学性能影响

The effects of porosity and external loading on hygrothermal tensile mechanical properties and interfacial failure mechanism of CFRP laminates were studied by high and low temperature alternating accelerated hygrothermal cyclical test and finite element simulation. 3 kinds of laminates with different porosities were prepared by controlling molding pressure. The load on specimen was 30%, 40% and 60% of the maximum bending load of laminates, respectively. The results showed that the increase of porosity was the main reason leading to the sharp decrease of tensile properties of CFRP laminates after hot-humid aging. The greater the porosity was, the more hygrothermal tensile strength decreased. The external load could accelerate the debonding of the interface between fibers and resin matrix, further degraded the hygrothermal tensile strength of the composites, and had different effects on the laminates with different porosity. Among of them, the most influential one was the laminate with porosity of 0.08, the second was the laminate with porosity of 0.04, and the least was the laminate with porosity of 0.11. And the greater the load, the greater the impact, but the influence of load on the hygrothermal tensile properties of the laminates was far less than that of the porosity. ABAQUS software was employed to simulate tensile properties of composite specimen. The tensile stress distribution of the laminates was investigated, and it was found that the tensile stress increased at 90 degree layer due to the hydrothermal cycle. Therefore, the matrix cracking and fiber/matrix interface debonding were prone to occur, resulting in the decrease of mechanical properties, which was consistent with the experimental results. The variation trend of tensile mechanical strength calculated by the ABAQUS software was consistent with the experimental results.