Curing Deformation Analysis And Optimization Design Of Fiber Reinforced Composite Autoclave

Fiber composite materials can be integrally formed by autoclave,which can reduce the number of bolted connections and enhancing structural rigidity,on the other hand,it can also form parts of other shapes with good molding quality.However,due to the internal and external factors such as chemical shrinkage strain,thermal strain and residual stress,the cured deformation of parts after demoulding will result in assembly difficulties,reduced component performance and even scrap.By establishing an accurate and efficient deformation prediction model,exploring and summarizing the curing deformation law,optimizing the process parameters and mold surface,it is of great significance to improve the quality of composite molding.Therefore,this paper combines numerical simulation,experimental research and theoretical derivation to carry out the following three tasks.Firstly,the current problem of composite curing deformation is that FEM progress is complexation and many model parameters are difficult to obtain,this paper proposes a simplified simulation scheme based on the path-dependent model to describe the mechanical of the composite material during the cure schedule.It's mainly considers the curing deformation and residual stress caused by the chemical shrinkage and thermal strain,the resin in different states,rubber state or glass state,are both assuming the material property is constant.In order to verify the correctness of the scheme in this paper,establishing a literature example by using the simplified scheme and comparing the results with the experimental spring-back angle.Secondly,the C-shaped shell model can be used as curved surface parts and the corner connection of L-shaped and U-shaped components,which is widely used in predicting deformation.In this paper,Similar theoretical deformation formulas of C-shaped cone shell model were obtained by the principle of virtual work and the assumption of small deformation in aircraft structures.The difference in those two shapes was the angle,which between the axis of the C-shaped truncated cone model and the busbar was not equal to zero.The error between the orthogonal experiment and the simulation results is within10 %,which indicated the rationality of the formula in this paper.The nose cap can be simplified as a combination of two C-shaped structures and analyzed by two FEM at the same way,different analysis results are consistent with experimental data,theoretical solutions with thermochemical effects are identical to path-dependent models,but the thermoelastic model has large deformation due to its high assumed material properties.Finally,in order to reduce the shape deviation caused by spring-back between molded parts and design,adding deformation reversely to die by surface compensation method of node displacement.By optimizing the mold shape to improve the curing deformation,it can improve most of the deformation at a time.