Numerical Simulation Research On Curing Process Of Composite Considering Mould Effect

High-performance composite materials have gained a widespreadapplication in muti-industries, such as aerospace, military, civil engineering andenergy transmission, because of their high specific modulus/stiffness, outstandingdesignability, and excellent corrosion resistance. During the curing process ofcomposite shell, the variation of the temperature field will directly affect thedegree of curing, and further affect the quality and performance of the curedcomposite shell. The mould has a great influence on the temperature field ofcomposite, and the accurate simulation of the heat transfer between the mouldand composite is the condition for the analysis of the temperature field. Thethermal expansion and contraction behavior of the materials, the exothermicchemical reaction of the resin, the chemical shrinkage, and the difference in thethermal expansion coefficients between the composite and the mould all willresult in the curing deformation, in which the curing deformation induced by themutual effect between the composite and the mould is quite complex.In this paper the external curing of a pipe fitting was taken as an exampleand numerical simulation of heat transfer and deformation during the curingprocess was performed. Thermo-chemistry model, curing kinetic model, thermalstrain and curing shrinkage strain model were built, and the finite elementmethod was adopted to solve these mathematics models. The validity ofalgorithm was test. Thermal analysis and curing deformation analysis modulewere created based on finite element analysis software ANSYS and APDL. Acomposite pipe fitting model with mould and two models without mould basedon different assumptions were built. The heat exchange between the mould andcomposite was analyzed during the curing process, and further the influence ofmould materials on temperature field and curing degree was evaluated. On thebasis of the thermal analysis, the curing deformation induced by the mismatch ofthe thermal expansion between the mould and the composite was analyzed considering the thermal strain and curing shrinkage strain, and the effect of thestacking sequence of multi-layers on the curing deformation of the compositewas also evaluated.In the paper, the influence analysis of different mould materials on curingprocess shows specific heat and heat conduction coefficient of mould both hadeffects on the temperature field of composite. When the heat conductioncoefficient was in some range, the heat conduction coefficient of mould waslarger, the heating and cooling rate of the composite was faster, and the peakvalue of temperature was lower. When it was out of this range, the changes of theheat conduction coefficient of mould had little influence on the curing process ofcomposite. The influence analysis of different stacking sequences on the curingdeformation shows adopting the symmetrical stacking sequence had smallerdeformation than asymmetrical stacking sequence. Therefore, the stackingsequence should be respected to reduce curing deformation which can be reducedby selecting the appropriate layer angles and stacking sequences. This researchimproves the molding efficiency of the process and the quality forming ofcomposite, and provides the theoretical basis and analysis method for the designand optimization of mould.