| As a kind of main material for car seat cover,coating fabric composite material,is increasingly used in the automotive industry.Because of their reasonable price and perfect appearance,it has got heavy attention by the majority of seat manufacturers.At present,most of the related researches about coating fabric composites material are mainly about their functionality,such as abrasion resistance,color fastness,etc.However,in production and practical use many problems occur on lateration,wrinkle and poor match of its mechanical properties with those of foam material.These problems promote the study of the mechanical properties of the foating fabric materials,which has now become an important research field.In this paper,an anisotropic Hyperelastic constitutive model of coating fabric material was established by combing the experimental data with theoretical analysis.The material model of the coating fabric was defined and realized using the ABAQUS subroutine,and was validated by a series of simulation.Furthermore,the established constitutive model was used to conduct the comparison of the body pressure distribution at the conditions with and without fabric cover.The result showed that it is unsuitable to do pressure distribution simulation only use the foam material without considering the seat cover material.The main works of this thesis are as follows:(1)The coating fabric composite material is composed of coating material and base cloth material.The coating fabric composite material is often an anisotropic material,mainly because of the anisotropy in the base cloth material.In order to obtain the mechanical properties and deformation characteristics of the coating fabric material along different directions,the uniaxial tensile tests and in-plane shear tests were performed in the warp and weft directions respectively.The uniaxial tensile tests were also performed for the coating and base cloth materials,which provided data support for subsequent single-material joint simulation.The Poisson’s ratios in the warp and weft directions of the coating fabric composite test samples were measured through image processing method,which provided adata basis for subsequent simulations conducted with the classic laminate constitutive model.(2)Based on the continuum mechanics theory and by the analogy to the establish of the constitutive models of the fiber-reinforced composites and the general hyperelastic materials,the anisotropic hyperelastic constitutive model of the coating fabric material was established,by decoupling the strain energy potential of the coating fabric material into the potential of the isotropic tensile strain energy of the coating material and the potential of the anisotropic tensile strain energy of the base cloth along the two directions.The model parameters were computed by fitting the experimental data.(3)The simulations of the uniaxial tensile test of the coating fabric composite materials were performed using the established hyperelastic constitutive model,the classic laminate constitutive model in ABAQUS,and the joint simulation of the coating and the base cloth material.In the simulation,the established hyperelastic constitutive model of the coating fabric material was inputted into the ABAQUS software by programming the UANISOHYPER_INV subroutine.The simulation and comparison of the results showed the validity of the established hyperelastic constitutive model.Due to the larger error of the single material joint simulation,a meso-geometric model of the knitted fabric base cloth was created by TEXGEN software,and the meso-geometric model was imported into ABAQUS to match the geometric model of the coating material for further creation of the finite-elements model and simulative study of the mechanical properties of the coating fabric material from the mesostructured angle.(4)The established hyperelastic constitutive model of the coating fabric material was used to conduct the simulation and comparison of the body pressure distribution at the conditions with and without cover material.The results showed that the influence of the seat cover material on the body pressure distribution might not be omitted.The main innovation of this thesis were:(1)Introduce the modeling method of the hyperelastic constitutive model of the fiber-reinforced composite material into the modeling of the coating fabric material for the base cloth of knitted fabric type.(2)Tried to model the constitutive properties of the coating fabric material by decoupling the strain energy potential of the coating fabric material into the potential of theisotropic tensile strain energy of the coating material and the potential of the anisotropic tensile strain energy of the base cloth along the经、纬向directions.(3)Wrote the UANISOHYPER_INV subroutine of the coating fabric constitutive model.(4)Conducted the quantitative study of the body pressure simulation with and without considering the cover material.The established hyperelastic constitutive model of coating fabric material can be used for the validation of the mechanical testing of materials and the simulations of other engineering applications,and has good theoretical and engineering application value. |
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