Research On Application Of Improved Genetic Algorithm In Roll Forming Of Polymer TOPAS(?)COC

As one of replication manufacturing technologies of micro-pattern,nanoimprint process takes advantages of high-efficient,low-consumption,and has high application range in the field of MEMS.Compared to other traditional process,thermal imprint process method has made great progress in material,structure and integration.Roller hot-embossing process evolved from plane imprint molding is a highly efficient continuous production method.With the high demand of pro-duction and the promotion of mass production,it is particularly important to study the rheological properties of the polymer in the vicinity of the glass transition temperature and the effect of the process parameters on the micro-structure quality.Firstly,the mechanicals state of amorphous polymer with the change of temperature has been analyzed in this paper.According to two kinds of hysteresis and energy loss,viscoelastic general-ized-Maxwell model of amorphous polymer near the transition temperature was established.Secondly,the optimization of solved parameters of amorphous polymer viscoelastic general-ized-Maxwell model for amorphous polymer TOPAS(?)COC model were determined using im-proved genetic algorithm.The main structure,steps and design methods of the improved genetic algorithms(GA)are described accordingly in the thesis.The objective function during for the opti-mization was measured using the degree of deviation of fitting results between the theoretical and the experimental results.The parameters of the proposed viscoelastic model are determined in the specific search space.In addition,comparison between the results using least-squares method and GA method was conducted.The agreement between predicted and experimental using GA is better than that obtained by using least-square method,and shows that the genetic algorithm is superior to the least-square method in accurate.To describe the temperature effect,the master curve can be obtained in the terms of the principle of transition at the reference temperature.The Prony series Maxwell model parameters are then calculated and input into the ABAQUS finite element soft-ware to simulate deformation of roller hot-embossing of microstructure.At last,the effect of process control parameters(temperature,preloading,cavity spacing,and rolling speed)on elastic recovery rate of deformation was studied using ABAQUS finite element software.The simulation results show that the lower temperature,the larger preloading,the smaller cavity spacing and the lower the rolling speed will result in the smaller the elastic recovery rate of deformation.In final,the optimal process parameters are obtained using orthogonal test method.