塑料板材热成形过程三维温度场有限元分析潜热处理技术的研究

对塑料板材热成形过程的三维温度场进行有限元分析时采用动态内部热源的方法对潜热进行了处理。在成形过程中利用Ａｖｒａｍｉ方程来解出型坯结晶时任意时刻结晶度的大小，进而求得各单元释放的潜热量。在利用Ｃａｌｅｒｋｉｎ有限元公式求解温度场时采用动态内部热源的方法计算了潜热时温度的影响，对塑料半球形件的温度场进行了计算，并对是否考虑潜热两种情形的温度场进行了比较。     

Thermoforming process of amorphous polymeric sheets: Modeling and finite element simulations

A temperature and strain rate dependent model for the thermoforming process of amorphous polymer materials is proposed. The polymeric sheet is heated at a temperature above the glass transition temperature then deformed to take the mold shape by the means of an applied pressure. The applied process temperature is taken uniform throughout the sheet and its variation is due only to the adiabatic heating. The behavior of the polymeric material is described by a micromechanically‐based elastic‐viscoplastic model. The simulations are conducted for the poly(methyl methacrylate) using the finite element method. The polymer sheet thickness and the orientation of the polymer molecular chains show an important dependence on the process temperature, the applied pressure profile, and the contact forces with the mold surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007