This research aims to design and control a full scale gun recoil buffering system which works under real firing impact loading conditions. A conventional gun recoil absorber is replaced with a controllable magnetorheological (MR) fluid damper. Through dynamic analysis of the gun recoil system, a theoretical model for optimal design and control of the MR fluid damper for impact loadings is derived. The optimal displacement, velocity and optimal design rules are obtained. By applying the optimal design theory to protect against impact loadings, an MR fluid damper for a full scale gun recoil system is designed and manufactured. An experimental study is carried out on a firing test rig which consists of a 30 mm caliber, multi-action automatic gun with an MR damper mounted to the fixed base through a sliding guide. Experimental buffering results under passive control and optimal control are obtained. By comparison, optimal control is better than passive control, because it produces smaller variation in the recoil force while achieving less displacement of the recoil body. The optimal control strategy presented in this paper is open-loop with no feedback system needed. This means that the control process is sensor-free. This is a great benefit for a buffering system under impact loading, especially for a gun recoil system which usually works in a harsh environment.

PLZT ceramics have exhibited promising applications as wireless photo-driven micro actuators for their direct conversion from optical energy to mechanical energy. However, the slow response of photodeformation and the residual photovoltage and deformation prevent PLZT ceramics from being employed as micro actuators, especially in the high frequency dynamic field. The primary purposes of this article are to analyze the response characteristics of PLZT ceramics and look for some measures to improve the response performance of the photo-induced deformation. To this end, this study observed the slow response, the residual photovoltage and deformation through photostrictive static experiments. Some measures proposed to accelerate the response speed and eliminate the residual photovoltage and deformation in this paper were experimentally confirmed. From these experiments, the hysteresis phenomenon caused by temperature rising, the residual photovoltage and photoinduced deformation after turning off the ultraviolet light are considered to be the main reasons for the slow response of photo-induced deformation. The experimental results indicate that reducing the effect of temperature elevation, ground connection and using another PLZT ceramic to eliminate the residual photovoltage and deformation are proven ways to improve the response performance of photo-induced deformation. On that basis, two optical driving mechanisms were proposed.

The primary purpose of this paper is to propose a mathematical model of PLZT ceramic with coupled multi-physics fields, e.g. thermal, electric, mechanical and light field. To this end, the coupling relationships of multi-physics fields and the mechanism of some effects resulting in the photostrictive effect are analyzed theoretically, based on which a mathematical model considering coupled multi-physics fields is established. According to the analysis and experimental results, the mathematical model can explain the hysteresis phenomenon and the variation trend of the photo-induced voltage very well and is in agreement with the experimental curves. In addition, the PLZT bimorph is applied as an energy transducer for a photovoltaicelectrostatic hybrid actuated micromirror, and the relation of the rotation angle and the photoinduced voltage is discussed based on the novel photostrictive mathematical model.

Lead lanthanum zirconate (PLZT) ceramic has been widely studied as an opto-electromechanical actuator activated by ultraviolet light for active vibration control of various structures. However, the slow response time of photodeformation and the hysteresis phenomenon between the photovoltage and photo-induced deformation greatly affect the performance of PLZT as an actuator. The primary purposes of this article are to provide a comprehensive analysis on the hysteresis phenomenon and seek the reason of the hysteresis phenomenon with the experimental method. To this end, this study proposed the hysteresis phenomenon by photostrictive static experiments and investigated the possible influence factors on the hysteresis phenomenon through a series of experiments. The experimental results indicate that the temperature elevation of PLZT ceramic subjected to light illumination plays a significant role in the hysteresis phenomenon. Therefore, reducing the temperature rise of PLZT ceramic exposed to ultraviolet light is an effective means to eliminate the hysteresis phenomenon and improve the respond speed of photo-induced deformation.

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