Lamination Modeland Thermoforming Process Investigation Of Carbon Woven Fabric Reinforced Thermoplastic Composites

Carbon woven fabric reinforced thermoplastic composites are widely used in advanced machinery,military industry,aviation and aerospace and other fields due to their advantages of high strength,high toughness ratio,no chemical reaction in the forming process,recyclable recycling,etc.Its thermoforming process has received extensive attention because of its high efficiency,low cost and suitable for mass production.But the process involves large deformation,anisotropy and multi-field coupling phenomenon.In order to characterize these mechanical behaviors of carbon woven fabric reinforced PEEK thermoplastic composites,a lamination model combining thermoplastic resin and woven carbon fabric was established based on continuum mechanics and finite element method.In the study of the constitutive model of poly-ether-ether-ketone(PEEK),taking into account the mechanical behavior of metallic materials and nonmetallic polymers,based on the traditional JC constitutive model and related literatures,a piecewise JC constitutive model was established for PEEK in consideration its three mechanical states at different temperature.The proposed piecewise JC constitutive model can better predict the flow behaviour of PEEK at different strain,different strain rate and different temperature.For the carbon woven fabric,an anisotropic hyperelastic constitutive model based on continuum mechanics theory is selected.Using FORTRAN language,based on the user-defined subroutine UMAT and UANISOHYPER_INV of commercial finite element analysissoftware ABAQUS/Standard,user subroutines are coded for PEEK and carbon woven fabric,respectively,and then merged.Compared with the method of predicting the forming properties of carbon woven fabric reinforced thermoplastic composites solely using the hyperelastic constitutive model of carbon fiber woven fabric,the proposed lamination model is reliable and effective.At the same time,the effects of different temperature,different blank holder forces and different fiber orientations on the forming properties and wrinkling defects of thermoplastic composites were studied.The results show that the three factors have important influence on the forming of thermoplastic composites.The selection of suitable technological parameters can ensure the quality of the molded parts and prevent wrinkling defects,and provide an important reference for the actual production and processing.