Study On Assembly Variation Analysis For Thin-Wall Composite Aerostructures

The assembly of composite components is a very important part of the manufacturing process for the composite production, and the dimensional quality of assembly is a key element to reflect the production level of the assembly process or even the composite products. Especially for aerospace composite products, assembly dimensional accuracy will directly affect the appearance and aerodynamic characteristics of the products. Therefore, control the assembly variation and improve the assembly accuracy is of great significane for the composite product.Currently, the assembly of composite products usually adopt the traditional assembly methods of metal structures, which is not suitable for the anisotropic composite structures. For the composite structures, part variations have significant impact on the assembly variation, and it is important to establish their relationship. The cure-induced deformation is the main factor affecting the shape accuracy for the thermosetting resin matrix composite structures in the autoclave molding process. In engineering practices, the deformation is usually eliminated by optimizing the cure parameters and modifying the mold surface in an expensive trial-and-error effort based on a large number of experiments, which will inevitably lower the production efficiency, improve the manufacturing cost.To this end, this paper carried out systematic research on how to analysis and forecast the assembly variation of the composite produts. On the basis of the Finite Element Analysis method, this thesis focuses on the simulation of the temperature field distribution of the composite component during the curing process, the prediction of the cure-induced dimensional deformation and developing a regression-based dimension variation model for the typical composite strutures such as L-shaped and C-shaped components, aiming to conduct the assembly variation analysis and optimization for composite products.The following are the main researching work in this paper.(1) the FEM simulation of the temperature field distribution of the thermosetting resin matrix compositeBased on analyzing the heat transfer route and rule of composite components in the curing process, the cure kinetics equation is introduced into the Fourier's heat conductive governing equation through the internal heat generation pattern, and according to the composite material properties in different curing conditions, a three-dimensional finite element analysis model is developed for simulating the temperature field distribution of the composite component during the curing process. The curing temperature field of the composite components are simulated by ABAQUS and its user subroutines, which is the basis for prediction the deformation of composite components.(2) the cure-induced deformation and a regression-based dimension variation model for the thermosetting resin matrix compositeBased on the research of the thermal deformation FEM model and the transient temperature data of the nodes obtained from the curing temperature field, the cure-induced deformations are implemented by ABAQUS and the regression-based dimension variation models are developed for the L-shaped and C-shaped typical compostie components.(3) assembly variation analysis of thin-wall composite aerostructuresBased on the the regression-based dimension variation models of the typical compostie components, an approach called the structural tree method (STM) was developed to analysis the deformation of the components and assembly. The method is verified to be effective through an example of variation analysis for a composite assembly. In summary, this paper presents solving solutions on three key technologies: the simulation of curing temperature field, the forecast of the cure-induced deformation and the assembly variation analysis for thin-wall composite components. The FEM simulation of the cure-induced deformation is conducted by using the Abaqus secondary development. The methods developed in this paper provide an effective tools for design for assembly (DFA) of composite products.