An Anisotropic Hyperlastic Constitutive Model And Forming Simulation For Carbon Woven Fabrics

Carbon woven fabric is a kind of reinforcement for fiber reinforced composites,which owns the advantages of high specific strength,high temperature resistance,good corrosion resistance,strong design ability and anti-fatigue resistance.So it is widely used in the fields of aerospace,defense,military and wind power generation.Under this background,deeply studying the mechanical behavior of stamping forming process for carbon fiber woven fabrics can provide a theoretical significance and engineering application value.In this paper,stamping forming process of carbon woven fabric has been systematically studied through carrying out material tests and forming experiments,representing a new mechanical constitutive model for composite woven fabrics and developing a user-defined subroutine in ABAQUS/Standard.The main research contents and conclusions are as follows:(1)Four types of material tests were carried out for a plain woven carbon fabric,including uni-axial tensile,biaxial tensile,bias-extension and picture-frame shear tests.The testing results show that the mechanical behaviors of the plain woven fabric are highly non-linear and strongly anisotropic under large deformation.In addition,biaxial tension coupling effect that mechanical behavior in the warp(weft)direction will influence that in the weft(warp)direction was observed in the mechanical test.(2)Based on continuum mechanics theory,an anisotropic hyperelastic constitutive model with biaxial tension coupling for woven composite reinforcements was developed.The strain energy per unit volume in the hyperelastic model is additively decomposed into three parts,representing the tensile energy from fiber elongation,compaction energy due to biaxial tension coupling in the warp and weft direction and shearing energy from interaction between warp and weft yarns,respectively.The method of determining the material parameters was given and then the parameters were obtained by fitting experimental data from uniaxial tensile test,equal-biaxial tensile test and picture-frame test.(3)The developed constitutive model was combined with CAE software ABAQUS by developing a user-defined subroutine.The constitutive model was applied to simulate a benchmark double dome forming.The simulation results including the biaxial tension coupling effect and without considering the coupling effects were compared with the experimental data separately.Finally,the comparison results show that the mechanical constitutive model including the biaxial tension coupling effect can better describe the non-linear anisotropic mechanical behavior caused by large deformation in the process of forming.(4)In order to study the distribution of shear angle and boundary profiles of the draped fabric,the square-box forming experiment and its corresponding numerical simulation were carried out.The results show that: the shear deformation is the main deformation mode in the process of forming and wrinkling will occur when the shear angle reaches the critical lock angle.(5)The proposed model considering biaxial-tension coupling effect in this paper is simple,useful and easy for material parameters identification.It provides a theoretical foundation for the numerical simulation and processing optimization of woven composites forming in the future.