塑料板材热成形过程三维温度场的有限元分析

塑料板材热成形过程中，温度通过影响流体粘度和流动行为指数对塑料板材的变形行为有着较大的影响。结合变形计算的刚粘塑性有限元公式、粘度计算的阿雷尼厄斯（Ａｒｒｈｅｎｉｕｓ）方程和威廉斯（Ｗｉｌｉａｍｓ）方程以及温度场计算的加权余量Ｇａｌｅｒｋｉｎ有限元公式，开发了对塑料板材热成形过程的变形和温度场进行数值模拟的三维有限元软件。求解塑料板材热成形过程三维温度场时，采用六面体单元，对热传导的动态边界条件、变形功转化的热即热力耦合以及潜热进行了处理。采用解析法和开发的三维有限元程序分别对热塑料件的热传导进行计算，证实开发的软件是正确的。本文对ＨＤＰＥ半球形塑料件热成形过程的变形和温度场进行了有限元模拟。模拟结果表明成形件的温度场分布直接受厚度分布影响，为采用简便的温度测量获取制件的壁厚分布数据提供了理论基础。

3 D FEM ANALYSIS OF TEMPERATURE FIELD FOR PLASTICS SHEET THERMOFORMING

Temperature has a big effect on plastics deforming behavior by influencing fluid viscosity and fluid behavior exponent Rigid visco plastic FEM is used to analyze the deforming process,Arrhenius equation and Williams equation are used to calculate the viscosity,and Calerkin FEM equation is used to analyze the temperature field,a software is developed to simulate the deforming process and temperature field of plastics thermoforming While 3 D temperature field is analyzed,solid element is adopted,dynamic boundary condition and heat energy come from thermal mechanical and latent heat are treated Through comparing the computation results by adopting analysis method and by the FEM program developed by authors,we can know that the develolped software is accurate The forming process and temperature field of HDPE hemispherical plastics parts are simulated in this paper The simulation result indicates that temperature field is directly influenced by the thickness distribution This offers a theory basis for obtaining the thickness distribution by simple temperature measurement in actual production