Manufacture And Mechanical Behavior Study Of Composite Folded Core Sandwich Structure

As a new type of aeronautic and astronautic load-carrying structure materials, the sandwich structure with composite folded cores has characteristics of high specific strength, specific stiffness and good energy absorption and will be expected to replace the conventional honeycomb sandwich structures for aerospace vehicles as the main load-bearing structural materials. However, the composite folded cores was inhibited to further progress for lacking experiment basis of manufacture methods and mechanical behavior. The purpose of this paper is to explore a simple way to manufacture the folded core realizing standardized, mass, and low cost preparation of the core and truly find its place in the field of engineering application verify the influence of different material and structure on the compression performance of the sandwich structure with composite folded cores by means of experiments and finite element simulation. Furthermore, it could provide reliable basis for theoretical research and practical application of this kind of sandwich structural material.In view of this goal, carbon and Kevlar prepreg textile were taken as raw material of the folded cores in this study.5℃,10℃,15℃,20℃ Cheating rate differential scanning calorimetry was used to determine the temperature of the curing process according curing kinetics and the optimal gel temperature, the curing temperature and post-curing temperature of prepreg are determined by extrapolation method. On this basis, the DSC isothermal scanning calorimetry was conducted at the gel and curing temperature. The degree of cure material versus time curve was determined by integration.Each stage curing time was got by the curves and gel test. A Set of hot Pressing mold was designed and manufactured,and the folded core was manufactured by hot-pressing method. With the target of improving the core compressive strength, each stage time and process pressure of curing process are optimized selection respectively.Compression experiments of composite folded core with different material, wall thickness and structural forms were carried out. The compression force-displacement and deformation failure mode of folded core with the relative density variation are studied by changing the core wall thickness. Its mechanical properties were explored by contrasting the compression force-displacement curves of different samples, and the mechanism of sandwich were studied by the deformation failure analysis as well. At last, the load-displacement relationship, failure mode and energy absorption characteristics of folded core structures and multilayer structures were evaluated and studied by the Static compression test.In order to explore the mechanical and adoption properties with different geometric parameters. The folded core geometry was analyzed and studied. The quasi-static numerical simulation was conducted by Ls/dyna finite element software and the reliability was verified.At last, the peak pressure, energy adoption influence of half-size space, flat folding half-field angle, the core height, the folding length and thickness of the folded core sandwich structures are discussed.