Experimental & Numerical Investigation Of Parameters Affecting Spring-Back of (CFRP) Reflector

Abstract

he carbon fiber reinforced polymer (CFRP) is extensively used for space and aerospace application due to their good specific properties over conventional metals and alloys. During the autoclave manufacturing process of laminated composite parts whose dimensions does not match with the mould from which they were made. This distortion commonly refers to as “spring-back or warpage”. The amount of spring back which is developed only depends on many process parameters like the manufacturing process parameters (cure temperature, resin bleed and applied pressure) the part parameters (geometry, material, cure shrinkage, thermal expansion and layup sequence) and the tool parameters (surface, thickness and thermal expansion). The work presented aims to determine the effect of various process parameters on spring back of the (CFRP) reflector. The process parameters like tool material cure cycle, thickness of laminate and layup sequences are considered. Two methods are planned for the study [a] numerical (simulation) [b] experimental. The experiments are conducted for manufacturing parabolic reflector using autoclave machine. Four types of mould materials are selected as per the least coefficient of thermal expansion (Stainless Steel Gr-430, Graphite, Invar 36, Cast Iron). Manufacturing of mould is carried out on VMC as per the CAD model of mould. Consolidation material and prepreg are selected and procured for conducting experiments on the basis of maximum cure temperature. Total seventy two parabolic reflectors are manufactured with considering different process parameters using autoclave process. The coordinates of manufactured reflector at internal surface are measured at two hundred different locations using 3D scanning. Spring back of reflector is obtained by taking difference of actual predefined coordinate with manufactured reflector coordinates. Thermochemical and stress deformation analysis are performed for curing process using COMPRO plug-in with ABAQUS software to measure spring-back deformation. The spring back deformation is compared for simulation and experimental method and found with good agreement.