Influence of thermo-oxidative aging on mechanical performance of three-dimensional orthogonal carbon/glass fiber/bismaleimide composites

Abstract

The effects of thermo-oxidative aging on the mechanical properties of three-dimensional orthogonal carbon/glass fiber/bismaleimide composite (3D-CF/GF/BMI composite) and laminated carbon/glass fiber/bismaleimide composite (LM-CF/GF/BMI composite) were studied by means of three-point bending and inter-laminar shear tests. The mass loss behavior, infrared spectra, macroscopic and microscopic morphology, bending properties and inter-laminar shear properties of the composites were analyzed at different aging time. The results show that a large amount of resin decomposition caused by thermal oxygen aging produces a large number of cracks on the surface and inside the composites, and the interface properties continue to decline. Eventually, the overall mechanical properties of the composite material decrease, resulting in the decline of the overall mechanical properties of the composite, but the performance retention rate of the 3D-CF/GF/BMI composite is always higher than that the of LM-CF/GF/BMI composite. This is because Z-binder yarns in the 3D-CF/GF/BMI composite exist, and the obstruction of the cracks propagating along the layers by Z-binder yarns can make all fibers together to resist external forces in the case of severe degradation of resin and interfacial properties. The "modified random process model" is used to predict all the bending strength of 3D-CF/GF/BMI composite aged at 200℃ for 180 days. The prediction error is less than 10%, indicating that the model is reliable.

Keywords

• three-dimensional orthogonal composite
• thermal oxidative aging
• mechanical performance
• aging mechanism
• strength prediction