Lead lanthanum zirconate titanate (PLZT) ceramic has draw significant attention for its promising application as a wireless photo-driven micro actuator. However, the residual photovoltage and photo-induced strain have a great influence on the response speed of photostrictive effect and prevent PLZT ceramic from using as a micro actuator, especially in high frequency dynamic field. In this paper, the coupled opto-piezo-thermo-elastic fields in PLZT ceramics were analyzed, based on which the mathematical equations of temperature, voltage and deformation during the light switched off phase were established. After that, the photostrictive static experiments were performed to validate the mathematical equations proposed.
To analyze structural dynamic response of rotary ultrasonic motor under high impact load, a theoretical model is established in this paper. A rotary ultrasonic motor includes two main components: stator and rotor. According to structure form and movement principle, they can be simplified as annular plates. When the system is imparted an impact load, dynamic displacement response of stator and rotor can be obtained. The damage to stator and rotor is analyzed in theory. It gave agreement with simulation and experimental result. Finally, influence of various structure parameters on the deformation of stator and rotor is analyzed and some suggestions on improving performance of rotary type ultrasonic motor are proposed.
This paper presents an investigation of a novel linear-type piezoelectric ultrasonic actuator for application in a Smart Fuze Safety System (SFSS). Based on the requirements of SFSS, the structural parameters of the proposed piezoelectric ultrasonic actuator are determined by fuze arming mode. Moreover, sensitivity analysis of the structural parameters to the frequency consistency is conducted using FEM software, after which the optimal dimensions are obtained with two close natural vibration frequencies. To validate the results of FEM, the frequency sweep tests of the piezoelectric ultrasonic actuator are performed to determine the motor’s actual working mode frequencies with PSV-300-B Doppler laser vibrometer system. Furthermore, the results of frequency sweep test are compared with that of the finite element analysis, and further verified by impedance analyzer. To investigate the overall performance of the piezoelectric ultrasonic actuator, vibration modes of actuator’s stator, output speed and force of the piezoelectric ultrasonic actuator are tested. The experimental results show that the output speed and force of the actuator can reach 88.2 mm/s and 2.3N respectively, which means that piezoelectric ultrasonic actuator designed in this paper can meet the demands of the SFSS.
PLZT actuators taken as one type of photo-deformable actuators have been widely applied for micro-driven systems and active vibration control of photostrictive laminated flexible structures. However, the slow response of photodeformation of single patch PLZT actuator greatly affects its application. In this paper, the main factors for the slow response of the PLZT actuator are investigated using experimental method. The increasing temperature during light on state and the residual photovoltage and photodeformation during light off state are considered to be the main factors for the slow response of the PLZT actuator. To improve the driving performance of PLZT ceramic, some effective measures through reducing the effect of increasing temperature and eliminating residual photovoltage and photodeformation are proposed and experimentally validated in this paper. Considering the effective measures proposed in this paper, two novel optical driving mechanisms based on PLZT bimorph and multi-patches combination for driving source are proposed.
Magnetorheological (MR) fluids contain suspensions that exhibit a rapid, reversible and tunable transition from a free-flowing state to a semi-solid state upon the application of an external magnetic field. This behavior has attracted significant attention in the development of dampers, shock absorption system, military and defence system and safety devices in aerospace engineering. However, many of the issues pertaining to MR damper behavior in impact and shock applications are relatively unknown. This study provides an experimental analysis and simulation analysis by using COMSOL multyphysics of MR dampers when they are subjected to impact and shock loading. To this end, a novel MR damper with a four-stage piston and independent input currents is designed and analyzed. In this paper, two-dimension symmetrical Computational Fluid Dynamics (CFDs) simulation for the laminar flow of an incompressible MR fluid in the annular gap in the presence of a varying magnetic field. The purpose of this research is to study the couple effect of electromagnetic field and the fluid flow field and magnitude of damping force in a macroscopic view. The governing differential equations describing the magnetic field and fluid flow in the annular gap are solved numerically by COMSOL Multiphysics. Through the electromagnetic analysis and flow field analysis, the coupling effect of the magnetic field between the coil and the multiphysics coupling effect of novel MR was be found. For the each coil has an independent power supply, so it can provide a wider range damping force by combining the electromagnetic field of coils.
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