Numerical Simulation Of Hot Forming Polycarbonate Sheet And Experimental Resaerch On The Forming Limit And Friction

Polycarbonate (PC) is a kind of thermoplastic material with good properties, and its products are widely used. There are many forming methods of PC and hot gas pressure bulging(HGPB) can manufacture double curvature, large dimension and high-quality parts, widely used in major machinery manufacturing such as military and automotive industry, becomes the focus of this area. But this approach has many process parameters which affect the part's quality, and any one of the various process parameters has a strong constraint relationship between each other. Therefore, the forming under the test guidance requires a lot of manpower, material and financial resources, and there isn't any material data for PC sheet in the pre-treatment database of existing commercial simulation software, then it is impossible to make the correct numerical simulation studies, so it becomes the difficulty in this area. To solve the tough problem, this paper will create a special finite element simulation platform of PC sheet hot forming.Because the main factors affecting the accuracy of the numerical simulation include high-temperature mechanical properties of PC sheet, friction conditions of the mold surface when bulging and the forming limit diagrams(FLD). This article studied the friction and forming limit theory firstly and determined the main factors which affect the friction and forming limit of PC sheet.The paper finished the friction test of PC sheet at different temperature, speed and positive pressure, obtained its friction performance data, analysed the friction coefficient effects of PC sheet under different process parameters, established PC sheet friction model on the basis of it. The paper has done the secondary development of the ABAQUS and embedded the friction model in the engineering software ABAQUS.The theoretical FLDs of PC sheet were predicted analytically based on the Marciniak- Kuczynski concept of localized necking. The FLD tests were carried out at different forming temperature, comparison between the theoretical FLDs and the experimental FLDs showed that the theoretical FLD model was accurate. In addition, FLD calculational model of PC sheet was built by fitting the experimental FLD data.This paper created a special finite element simulation platform of PC sheet hot forming which is composed of constitutive model of high temperature PC sheet, forming limit model and friction model. Do the finite element simulation of hot forming using this platform, compared the simulation results for HGPB of PC sheet with the experimental results, it was validated that the special simulation platform for PC sheet was accurate. Through doing the finite element simulation of broken specimen and unformed specimen and analyzing the strain, stress, thickness, displacement and the showed that the computing platform was accurate.