Studies On The Mechanical Properties And Constitutive Model Of IMD Film PET Material

A mold company they have encountered many problems with IMD(in-mould decoration)films during the manufacture process,such as wrinkle,pattern deformation.In order to slove this problems,we need to propose an constitutive model of PET(Polythylene terephthalate)material based on actual forming process.Aims to learning about material mechanical properties and deformation regulation of PET material.At the beginning,deformation behavior of IMD film during the forming process were studied.Acorrding to the actual deformation behavior we conduct an experiment requirement analysis,Secondly,then making some design jobs,Including experimental program and fixture design.In order to investigate the strain-rate and temperature sensitivity of PET material,Initial experiments carried out on the material,including the specimen tensile test and cyclic loading and unloading experiments;Through the fixture and experimental program improvement,we have designed uniaxial tensile experiment at various temperature and stretching speed,and then used Mathcad software to obtain the true mechanical properties of PET material.The mechanical properties index of elastic modulus,yield strength and elongation were analyzed.Using phenomenological modeling approach,based on experimental data and sophisticated polymer constitutive model to create a mechanical constitutive model for PET material.constitutive model divided for three parts:the temperature effect items,plastic deformation and strain hardening term,elastic deformation and strain softening items,the parameters were derived from experimental data.The material constitutive model is extended to three-dimensional state,and derived the Jacobian matrix.Using Fortran language to written an UMAT subroutine,Put it into ABAQUS software for a finite element simulaition and analysis,To verify the correctness of material subroutine,and also make some contribution for a further development of IMD films studies.