PID Control And Influence Research Of Relevant Parameters Of Laser-Controlled Separation

Laser-controlled separation, which induced crack propagation of brittle materials through thermal stresses, is a non-contact method. In order to improve cutting quality and simulation efficiency, three aspect of further research were proceeded.Firstly, the influence of material parametes with temperature behavior was researched. The transient temperature field during laser scanning was analyzed by using the theory of finite element method and thermal conduction. After the transient temperature field was obtained, thermal stresses of the crack tip were calculated by the thermo-elastic plane stress theory, and crack propagation was simulated by a correlative fracture criterion and node relaxation method. The simulation under the consideration of temperature behavior of material parametes was carried out by the method. Compare of different aspects, such as the maximum temperature,the maximum stress of different stress field and the paramete range of continuous separation, were analyzed between results of temperature behavior material and those of non-behavior.Secondly, the influence of PID control on convergence of iteration path was carried out. The iteration formula was established by PID control method in order to optimize laser scanning path. By forcing the crack propagation along desired path, the deflection angles between the desired crack propagation direction and that predicted at each increment can be calculated, by which the actual fracture trajectory can be evaluated. The iteration based on the formula is carried out till the desired crack propagation direction approaches the predicted. The most conformable PID parameter was optimized in order to make the convergence as fast as possible.Thirdly, the influence of correctional initial path on convergence of iteration was investigated. A correctional iteration method of laser scanning path was established for the solution of the laser-controlled separation of certain problems. The simulation results show that this influence could be so large that convergence speed and even the possibility of convergence were involved.