A Study On The Thermoforming Properties Of PEEK Sheet

Being a new type of special engineering plastic,Polyetheretherketone(PEEK) has received widespread attention. Because of its excellent physical and chemical properties,PEEK is used in various fields such as aerospace,automotive,medical and so on.As a new forming process,plastic thermoforming technology has many advantages,such as good adaptability, wide range of applications, high production efficiency, high utilization rate of waste materials,etc. The application of thermoforming technology in the PEEK production will greatly improve the production efficiency, save the production cost and expand the application range. In this paper,a systematic study of thermoforming properties of PEEK sheet was carried out.In this paper,PEEK was selected as the research object,and basic mechanics dates of PEEK were accumulated through a large number of tensile tests at different temperatures and speeds, the PEEK basic laws of mechanics was summarized at high temperatures. The results showed that the high temperature mechanical response of PEEK is sensitive to the temperature and strain rate. At the temperature interval between the glass transition temperature and the melting point,PEEK exhibits characteristics such as strain hardening,strain rate dependency, temperature soften and so on.According to PEEK mechanical properties at high temperatures,constitutive model of PEEK was established at high temperature,and the various parameters of this model were determined by experimental approaches. By use of the user subroutine interface of ABAQUS, this constitutive model was achieved by programming method. The correctness of this model was verified through the numerical simulation method.The impact of pivotal process factors such as forming temperature and forming speed on PEEK thermoforming properties was studied through the combined method of experiments, theoretical analysis and numerical simulation. The results showed that forming temperature is the most important factor affecting the thermoforming properties of PEEK,the thermoforming properties of PEEK performed best at 200℃,and the forming speed can be set according to actual needs.Hot forming limit experiments of PEEK were carried out. PEEK hot forming limit curves were obtained at different temperatures,and the corresponding calculation model was established. The accuracy of the calculation model was proved by fitting method. A theoretical basis was provided to predict rupture site and break-up time of PEEK sheet in the numerical simulation and actual production.This paper carried out a step by step research by the combined methods of experiments, theoretical analysis and numerical simulation,got a preliminary understanding of the PEEK thermoforming properties, obtained certain academic achievements,And provided some reference and guidance for the thermoforming process of PEEK sheet.