Study On Heat Conduction Of Warp-knitted Spacer Fabrics Reinforced Composites

Warp knitted spacer fabric is a kind of three-dimensional textile structure with hollow structure.Its reinforced composite material has the characteristics of high strength,heat insulation and good impact resistance.Based on the structural characteristics of spacer fabrics and the advantages of core development,the design of spacer fabric reinforced phenolic composite and spacer fabric reinforced PMI foam composites was designed.The thermal conductivity of two composites was predicted by finite element method,and the equivalent thermal conductivity was calculated to characterize the thermal insulation performance of the composites.The research contents are as follows:(1)Greate a multi-scale model of spacer fabric reinforced composites.The resin matrix composite model includes the micro scale model of the dipped fiber bundle and the mesoscale model of the spacer fabric reinforced resin composites;the enhanced foam composite model includes the full scale model of plain panel and spacer fabric reinforced foam composite,and the finite element method is used to simulate the heat conduction of the multi-scale model.Behavior.(2)The thermal conductivity of the micro scale model of impregnated fiber is transversely isotropic,and the thermal conductivity of the material increases with the increase of fiber volume fraction.(3)The thermal conductivity of the spacer fabric reinforced phenolic resin composite is the best in the thickness direction,followed by the warp direction and the weft direction.Due to the anisotropy of the hexagonal mesh spacer fabric,the overall temperature and heat distribution of the composites are highly inhomogeneous.In addition,with the increase of the diameter of the spacer fiber,the thermal conductivity of the composite increases in the thickness direction.(4)In the analysis of thermal conductivity behavior of plain fabric composite panel model,it is found that the thermal conductivity difference of two-phase materials and the direction of temperature gradient affect the heat transfer,and the latter has more obvious effect.The thermal conductivity of composite panel in thickness direction is greater than that in weft direction.(5)Spacer fabric reinforced PMI foam composites result in different heat transfer processes in different directions due to the structural characteristics of diamond mesh spacer fabrics.This difference is more obvious in the spacer yarn,and the thermal conductivity in the thickness direction is the largest,and the thermal conductivity in the direction of the zonal thermal conductivity is the smallest.There is a correlation between the structure and the structure.The influence of composite panels and spacer fabrics on the thermal conductivity of composites is analyzed.It is found that the temperature distribution and heat flux transfer of sandwich composite materials are related to the thermal conductivity and mesoscopic structure of spacer fabrics.The thermal conductivity of the material is improved by the spacer fabric,and the composite panel improves the heat insulation performance of the spacer fabric reinforced PMI foam composites.