High Temperature Mechanical Properties Investigation Of Hybrid Continuous Fiber Composites

Hybrid continuous fiber reinforced composite(HCFR composite)is a new design of lightweight ablation and heat-preventing materials.Its components are quartz fiber,glass fiber,polyphenylene sulfide(PPS)fiber,phenolic resin.And glass microspheres dispersed in the phenolic resin.Due to the complicated heat-preventing mechanism of the complex component materials and the complex microstructure evolution of the materials under high temperature conditions,the prediction and analysis of the high-temperature stiffness and strength properties of the materials pose challenges.In this paper,the evolution process of stiffness and strength properties of different component materials under high temperature conditions is studied from a mesoscopic perspective.A meso-analytical model is established to predict the hightemperature stiffness performance of the material.Combined with the macroscopic experimental test results,the macro-material high-temperature strength model is further established.The strength of the material was analyzed,which laid a theoretical foundation for the design and structural design of hybrid continuous fiber reinforced composites.First,modeling and analysis of the stiffness properties of component materials at high temperatures.The pyrolysis kinetics of the component materials was analyzed by thermos-gravimetric test results.The pyrolysis and phase transformation models of the component materials were established under high temperature conditions.The high temperature stiffness performance analysis method of the component materials was determined,and the mixing ratio and Chamis formula were used to predict.The high temperature effective properties of the matrix material and the fiber bundle material.Secondly,a meso-analytical model is established for hybrid continuous fiber reinforced composites,and the high-temperature stiffness properties of the overall material are predicted based on the properties of different component materials.The ambient temperature quasi-static compression experiments were carried out on HCFR composites.The high temperature pyrolysis materials at different temperature points were observed by Micro-CT,and the crack density at different temperature points was counted.Combined with the observation data of composite mesostructures,The representative volume unit model of the composite material was established,and the effective performance of the composite material at different temperature points was predicted by the finite element method.The attenuation trend of the composite material stiffness with increasing temperature was obtained,and the attenuation was not linear but The phase transition and pyrolysis process are closely related to the curve-stage trend;under high temperature conditions,many macroscopic cracks appear in the cracking and phase transformation of the component materials.MicroCT based observations introduce macroscopic cracks in the representative volume cell model.The effect of cracks on the high temperature stiffness of the material.Finally,combined with the high-temperature compression test strength performance,the strength analysis model suitable for the material is obtained based on the empirical strength model.It is found that the macro-strength analysis model of the material can predict the high-temperature compressive strength performance of the material well.The high temperature strength experimental performance data further determines the macroscopic high temperature stiffness performance of the material,which is consistent with the macroscopic high temperature stiffness performance of the material predicted by the mesoscopic method.