Research On Lightweight Design Of Frame Molding Die For Composite Materials Based On Stiffness Constraint

With the increasing application of composite materials in aircraft,composite material components are also moving towards large-size components,so it puts forward higher requirements for its manufacturing.Since the mold is main tool in the shaping of composite material components,the dimensional stability is important in using,at the same time,in order to reduce the heat capacity of the mold and shorten the curing period of the prepreg,it is necessary to reduce the quality of the mold while ensuring the functionality of the mold.In this paper,the lightweight design of the mold is proposed to reduce the mold quality and thermal deformation of frame mold,the main work is summarized as follows.First,the finite element simulation methods of the mechanical and thermal deformation of the frame mold under various working conditions are studied and presented,and the deformation trend of the mold is analyzed.The parameterized model is established in CATIA and ANSYS with the CAPRI interface,and the temperature distribution of the mold is simulated by Fluent,the deformations of mold in various working conditions are analyzed by these models.The accuracy of the simulation is verified in comparison with the experiments,and it is found that the trend of the thermal deformation and the temperature difference of the mold was the same,and the peak value appeared at the end of the temperature rise.Second,according to the optimization needs of different parts in the mold support structure,the optimization methods are studied and achieved.Such as the optimal clapboards layout is determined by analysing the deformation of the mold with different numbers of U/V-direction clapboards.Then use the analytic hierarchy process to determine the weight ratio of the deformations in various working conditions,the topological optimization for the bottom frame form and the ventilation hole shape of the mold are performed by ABAQUS.At last the appropriate position of the lifting ring and the forklift slot are calculated by Screening method.After comparing the optimized mold with the original mold,it can be seen that the deformation in various working condition of the mold is significantly reduced,which proves the rationality of the optimization.Third,the lightweight design method of size optimization is proposed with sensitivity screening and RSM.The size parameters that have significant effects on the mold deformation and quality are screened by LHS and the Spearman rank correlation coefficient.Then the mathematical model of response surface is establised by CCD,and the accuracy of the model is verified by regression equation coefficient and finite element simulation,lastly the NSGA-II method is used to calculate the pareto optimal solution.The method was applied to a mold example,and the lightweight deformation reduced the mold thermal deformation by 26% and the mold quality by 12.5%.