| Carbon fiber composites have been widely used in the automotive field due to the characteristics of light weight,high strength,high temperature resistance and corrosion resistance.The application of carbon fiber composites to automotive parts ensure their sufficient mechanical properties while greatly reducing their own weight.It promotes the development of lightweight vehicles.However,composite parts are affected by many factors during the curing process,resulting in residual stresses inside the components after curing.So,it produces curing deformation.The existence of curing deformation will have a certain impact on the subsequent processing and connection assembly,which is easy to cause non-fitting between the connection interfaces.It is easy to produce assembly stress and cause secondary damage.In view of the above problems,this paper selects the L-shaped composites connector with R angle used in automobiles as the research object to study the curing process and deformation of the parts.To explore the influence of various factors on the curing deformation of composites and provide a theoretical reference for alleviating the curing deformation of carbon fiber composites.At the same time,as the residual stress in the composite parts after curing is not completely eliminated and affects the subsequent machining process.On the basis of the completion of curing,the effect of component residual stress on the subsequent machining deformation is studied.The main research and achievements are as follows:(1)Combining the resin curing kinetic model and the heat transfer model,a HETVAL subroutine for calculating the curing heat release was developed to simulate the distribution of the temperature field and curing degree field of the composite parts during the curing process.The comparison of some literature results verifies the subroutine was correct.At the same time,the UEXPAN subroutine for calculating thermal strain and resin chemical shrinkage strain was developed and combined with the UMAT subroutine to update the stiffness matrix and stress.According to the existing test data,the finite element model of the L-shaped composites with R angle is established to simulate the components curing process.It was found that after the curing,the components produced spring in deformation.Then,the deformation results were compared with the test results to verify the effectiveness of the model and the simulation.(2)From the perspective of the curing process,the effect of different curing process parameters on the curing deformation of the composite parts was studied.The results show that with the increase of temperature rise and cooling rate,the spring in deformation of the component increases;when the curing process temperature is increased,the spring in deformation of the component increases;when the curing time is shortened,the spring in deformation of the component increases.Therefore,it is possible to reduce the degree of spring in deformation of the component by appropriately reducing the rate of rise and fall,reducing the curing temperature and extending the curing time.(3)Analyze the influence of component geometric factors on self curing deformation.The study found that the asymmetric layer caused the largest spring in deformation;as the angle R angle increases,the spring in deformation of the member decreases;the plate thickness increases,the spring in deformation decreases;the radius of R angle has little effect on the spring in deformation of the component.(4)The simulation of the machining process of the component based on residual stress is carried out.Under the same circumstances,as the milling thickness increases,the final spring in deformation of the component decreases;the milling method has no effect on the final deformation;the selection of the milling sequence from the inside to the outside of the R angle causes large amount of deformation of the component,which is more conducive to the relief of spring in deformation of the component. |
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