Optimization method to select temperature based on chemorheological and exothermal reaction of RTM

Abstract

Heating mold and resin have been widely used in resin transfer molding (RTM) to improve injection and manufacturing efficiency. The unreasonable mold/resin temperatures sometimes lead to excessive viscosity of resin and premature curing, which will result in failure of the filling process. Selection of optimal mold and resin temperature has become a source of concern in the polymer industry. This article presents an optimization method to select mold and injection resin temperatures by using numerical simulation based on chemorheological and exothermal reaction of the RTM process. The results show that the optimization method has high computational efficiency for three-dimensional parts with different shapes. The selected mold/resin temperature ensures the smooth filling process, which provides a powerful tool for parameter design in polymer industry.

Optimization method to reduce three‐dimensional thermal gradients in resin transfer molding

“…Figure shows the maximum temperature curve at mold temperature (65 °C) calculated by nonisothermal method. The temperature obtained by nonisothermal method is the maximum temperature which is higher than the actual process . Therefore, the temperature of resin which its injection time is less than t 4 at the end of filling stage must be lower than T fMax .…”

“…In our previous research, we have proposed the “nonisothermal method” to optimize initial temperature. The energy equation is used to calculate the change of resin viscosity and curing degree at every mold temperatures in this method.…”

“…Meanwhile, the initial temperature of part is set same as the mold wall. The maximum curing degree and viscosity are calculated to obtain gel and low viscosity time of the resin at different initial temperatures …”

“…Meanwhile, the curing degree of resin at the injection port is basically zero because of the short flow time. The initial injection temperature can be calculated by the initial resin viscosity model () without considering the curing degree . As shown in Figure , the injection temperature of 31 °C at which the viscosity is 0.29 Pa·s is selected in order to keep the viscosity and temperature in a lower value.…”

“…Therefore, the process of RTM is nonisothermal and temperature plays an important role in the whole process . Moreover, the curing reaction of resin is exothermic and sensitive to temperature . Unreasonable heating system can easily lead to a nonuniform development of the curing reaction then resulting in large thermal gradients, which include the temperature gradients and curing degree gradients .…”