Determination of Spring Back Deformation for Carbon Fiber Reinforced Polymer (CFRP) Reflectors

Abstract

The Carbon Fiber Reinforced Polymer (CFRP) is extensively used for space application due to their good specific properties over conventional metals and alloys. Autoclave processing is used for manufacturing of composite part for space and aerospace applications. During processing in autoclave the manufactured composite part contains dimensional inaccuracy such as spring back and warpage. The spring back and warpage can be affected by different processing parameters such as cure cycles, tool geometry, composite ply layup sequence, tool material, tool surface condition, thickness of laminate and type of prepreg . The work presented aims to determine the effect of various parameters on spring back of reflector. The parameters considered are tool material, cure cycles, thickness of laminate, layup sequence. Two methods are planned for this study a) Numerical and b) Experimental. COMPRO, a customized software for simulating the curing process of composite material along with Abaqus is used for numerical simulation. Initially curing process simulation of L-shaped laminate is conducted using COMPRO software to validate the results with available literature for verifying the methodology used. The results of the study are in good agreement with the available literature results. Selection of the mould material, consolidation material and prepreg is performed for conducting experiments. Manufacturing of mould is carried out on VMC as per the CAD model of the mould. The experiment for manufacturing of reflector is conducted using hot air oven, steel mould material is used during the experiments. Coordinates of the manufactured reflector and mould are measured at fourty different locations using Coordinate Measuring Machine (CMM). Spring back of the reflector is obtained by taking the difference of reflector coordinates and mould coordinates. Study of curing process on dimensional stability of L-shape CFRP components is carried out. In the study rectangular cross section aluminum mould is used, on two faces of the mould laser engraving is done. During the experiments, portion of mould surfaces was treated with release agent and other with release film. Effect of laser engraving and mould surface condition is observed after demoulding of the L-shape CFRP parts. All engraved holes on the face of mould have their impressions on the manufactured composite parts and composite parts have better surface finish with use of release agent. Simulation of curing process of reflector is carried out using Abaqus and COMPRO by considering different parameters i.e., type of curing cycle, layup sequence and thickness of laminate. Simulation is conducted for eight different layups of prepreg. Layup having prepreg layers with four different orientation experiences least spring back magnitude. In addition to this, as the layup thickness increases spring back magnitude decreases.