Design Of The Structure And Research On Mechanical Properties Of PMI Foam Sandwich Shell

Polymethacrylimide (PMI) foam sandwich structure has high specific strengths and specific stiffness, and the excellent properties of heat insulation and wave-transparent properties, so it can be widely used in the field of large aircraft, rocket fairing, spacecraft, satellite cabin and so on. With the steady development of aerospace science and technology, the demands for structure design and properties of material are urgently increased. Foam-sandwich-structured materials with very stable process performance are very remarkable and promising in wide application field.This thesis studied the structure of PMI foam / Fiber Reinforced Plastics and optimized the design of the structure.First, 1,2-ethylenediaminem was used as curing agent, epoxy resin matrix is toughened by mixing up Polyether amines (D230). Pure ethylenediamine cured epoxy resins are brittle material.After adding D230, it can effectively increase the body casting cyberspace, and decrease the density of the crosslink, for the C-chain length of the D230 is longer than that of ethylenediamine. Therefore, epoxy resin matrix with low-defect, high strength and toughness could be obtained. Then the optimization quantity of the flexible amine (D230) fillings is determined through mechanical properties testing. The results shows that if quantity of the flexible amine (D230) comes up to 20%, the matrix shows the best mechanical properties.The fracture morphology was analyzed by SEM and verified the improving results with the addition of the flexible amine (D230). Then the resin casting was investigated by thermogravimetry (TG) test, its decomposition temperature is above 260℃, fully meeting the cabin thermal environment requirements.Then, PMI foam was used as the core material of sandwich structure, PMI/FRP sandwich materials are prepared. The mechanical properties of the structure are studied by lateral compression and three-pointbending experiment. Then the influencing factors of the mechanical properties of the structure are analyzed, the influence of glassepoxy thickness, the laminate orientation and the density of the PMI foam are discussed.Finally, one model rocket cabin was used as the background, simulating the sandwich of conical shell and cylindrical shell with reinforcer by the finite element software Patran and the mechanical properties are analyzed. Buckling analysis was done in reinforced sandwich structure, it also explained the effects of panel thickness, angle of fiber layer and the density of PMI foam to the mechanical properties in sandwich structures .