Design And Mechanical Properties Of Laminates With Different Sandwich Stitched Thermal Insulation Materials

This subject takes the sandwich material formed by the suture of continuous quartz fiber cloth and quartz chopped fiber mat as the research object,and uses the material’s high temperature resistance and high porosity characteristics to be used as a reinforcement material for aerospace insulation tiles.The compression resilience and heat insulation performance that are concerned in the material application field have been studied,and the main contents include the following aspects:(1)The quartz fibre needle-punched felt was chosen as the core,the quartz fibre fabric as the surface material and the quartz fibre bundle as the stitching thread.2 sets of stitching parameters and 3 specimen thicknesses were designed and the core felt and the surface fabric were stitched together as a whole by means of pierced stitching,the stitching process maintaining the tension of the stitching thread and making the surface of the fabric flat.(2)The compression resilience performance test was carried out by means of secondary loading.The one-way compression performance data showed that the material has good compressibility and the compression strain can reach about 50%.After the second loading,it was found that the peak load was slightly reduced,and the near complete rebound could be achieved instantaneously after one compression deformation,and the load time curves of the two loadings tended to be consistent,indicating that the material has good compressive rebound performance and can be used repeatedly.Analysis of the compression rebound mechanism,the compression rebound process of the specimen can be divided into two parts: the first part of the reboundable part,the other part of the non-reboundable part.The amount of rebound depends on the part of the material being compressed to failure,that is the material is compressed and the fibre breaks leading to failure.(3)The thermal conductivity of the material was tested in different specimen thickness directions to characterise the thermal performance index of the material.The results show that the stitching density has an influence on the thermal insulation performance of the material.The average thermal conductivity of the specimens with a stitch density of 5 mm × 10 mm was 0.06 W/(m·K),while the average thermal conductivity of the specimens with a stitch density of 5 mm×25 mm was 0.055 W/(m·K),with a difference of 9% between the two.The thermal conductivity of the sparse stitching density is small and the thermal insulation is good.The reason for this analysis is that the presence of the stitching increases the overall material thickness direction through the material,making the heat conduction path more complex when the material is subjected to heat flow impact.(4)Thermal assessment tests were carried out on the specimens using an alcohol torch to simulate the actual application environment.At the same stitch density,the greater the thickness,the lower the cold side temperature of the material and the better the thermal insulation properties.A material with a thickness of 30 mm had a cold surface temperature of 169 ℃ when heated to 240 s,while at the same time a material with a thickness of 10 mm had a cold surface temperature of 400 ℃.