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Shiyuan Luo,Yongxin Jiang,Sandrine Thuillier,Philippe Castany,Liangcai Zeng 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2
A simplified 3D FE model based on McCormick’s model is developed to numerically predict the spatiotemporal behaviorsof the PLC effect in Ti-12Mo alloy tensile tests at 350 °C with strain rates from the order of 10–4 s−1 to 10–2 s−1. The materialparameter identification procedure is firstly presented in details, and the simulated results are highly consistent withexperimental ones, especially in terms of stress drop magnitudes and PLC band widths. The distribution of simulated stressdrop magnitudes at a constant tensile velocity (0.01 mm/s) follows a normal distribution and its peak value is in the range of26–28 MPa. Furthermore, the simulated band width slightly fluctuates with the increase of true strain and its average valueis about 1.5 mm. Besides, the staircase behavior of strain–time curves and the hopping propagation of the PLC band areobserved in Ti-12Mo alloy tensile process, which are related to the strain localization and stress drop magnitudes.
Xiaoying Tian,Hui Peng,Xuguang Luo,Shiyuan Nie,Feng Zhou,Xiaoyan Peng 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.4
There is a class of typical nonlinear industrial process, which can be characterized by a first-order inertia plus pure delay model in an operating range, but the model parameters are different in different operating ranges. Usually, a set of Proportion Integration Differentiation (PID) controllers may be used to control the process, and the controllers have different parameters in different operating areas. However, the adjustment process of the PID controllers’ parameters is not an easy job in practice, and the control performance may also be not perfect. The Dahlin algorithm may provide very good control performance for the process, but its control performance may become very poor if the model parameters are not accurate and/or the input is constrained. Faced with this issue, this paper proposes an Operating-Range Scheduled Robust Dahlin Algorithm (ORSRDA) for the process control with input constraint, which is designed on the basis of a nominal first-order inertia plus pure delay model and the given parameters uncertainty. The process operating ranges are divided into pre-designed several zones accordingto the difference between output setting value and current output when a new setting appears. For each operating range, the parameters of ORSRDA are obtained by solving a min-max problem offline to guarantee the closedloop system’s robust stability and acquire the best step-response control performance. To eliminate the steady state error, the integration control action is added into the ORSRDA when the system output is close to its setting value. The proposed method is applied to temperature control of an experimental electric furnace to demonstrate its effectiveness and implement procedure.