Research Of Thermal-structure Coupling Deformation For The Radome Fabricated By PMI Foam Sandwich Structure

The thermal-structure coupling deformation will occur on the surface of the PMI foam sandwich structure airborne radome when the environment temperature is changed,which may even triggers the decrease of wave transparent properties under severe conditions.According to the requirement of thermal deformation analysis of airborne radome,the thermal-structure coupling deformation regulation of PMI foam sandwich structure radome was researched under several different conditions.Two types of resin casting(LT-5089 and 760E)and quartz glass fiber reinforced composite skin were prepared by vacuum bag pressure process,also mechanical and thermol properties were tested.The experimental results show that the tensile modulus of the two kinds of composite skin decreases significantly with the increase of temperature from 30? to 70?,but the thermal conductivity,thermal expansion coefficient and specific heat capacity of the skin,the casting and the PMI foam are almost unchanged.In order to simulate and analysis the radome thermal-structural strain regulation,the modeling was build by the finite element analysis software ANSYS.Some input parameters related with material properties was tested.When the radome fabricated by PMI sandwich structure experiences the process of heating and cooling,the whole body of the radome will expand.And the expansion strain will decrease gradually from the edge of the cover to the center of the wave penetrating plane.The whole presents the tendency of depression in the plane of the wave penetrating plane.At the same time,the decrease of skin thicknessand temperature change cycles,the deceleration of heating rate,the acceleration of cooling rate and the addition of 760 E in resin matrix can reduce the tendency of thermal deformation.At last,the temperature shock experiment of radome was carried out.The results show that the deformation regulation of radome after thermal shock test is consistent with the simulation results and the difference of the strain between calculated and experimental is less than 35.08%.The thermal shock test also shows that the maximum deformation of the PMI foam sandwich structure radome is less than 0.1mm,which satisfies the design requirements of radome.