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RISS 인기검색어
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- 저자 : Donghuan Liu (검색결과 2 건)
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Analysis on an improved resistance tuning type multi-frequency piezoelectric spherical transducer
Lei Qin,Jianjun Wang,Donghuan Liu,Lihua Tang,Gangbing Song 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.4
The existing piezoelectric spherical transducers with fixed prescribed dynamic characteristics limit their application in scenarios with multi-frequency or frequency variation requirement. To address this issue, this work proposes an improved design of piezoelectric spherical transducers using the resistance tuning method. Two piezoceramic shells are the functional elements with one for actuation and the other for tuning through the variation of load resistance. The theoretical model of the proposed design is given based on our previous work. The effects of the resistance, the middle surface radius and the thickness of the epoxy adhesive layer on the dynamic characteristics of the transducer are explored by numerical analysis. The numerical results show that the multi-frequency characteristics of the transducer can be obtained by tuning the resistance, and its electromechanical coupling coefficient can be optimized by a matching resistance. The proposed design and derived theoretical solution are validated by comparing with the literature given special examples as well as an experimental study. The present study demonstrates the feasibility of using the proposed design to realize the multi-frequency characteristics, which is helpful to improve the performance of piezoelectric spherical transducers used in underwater acoustic detection, hydrophones, and the spherical smart aggregate (SSA) used in civil structural health monitoring, enhancing their operation at the multiple working frequencies to meet different application requirements.
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Shift robust control during inertia phase for random disturbance load
Guoxiang Cao,Anlin Wang,Xiaotian Liu,Donghuan Xu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1
The automatic transmission of earthmoving machinery generally has problems of shifting shock and poor control robustness. Low-frequency high-energy random loads and large-space model uncertainties are the main causes of these problems. Therefore, we considered a type of wheel loader automatic transmission as the research object and propose a robust control method for the shifting inertia phase of the earthmoving machinery automatic transmission. The control method includes a robust controller b K , a disturbance compensation controller d K and a feedforward compensator f K . The robust controller b K is designed by μ synthesis method to resist the uncertainties of parameters and structure and guarantee the output speed to track the reference input. A load dynamic estimation method for random disturbance load of automatic transmission is proposed, which improves the compensation effect of disturbance compensation controller d K . The feedforward compensator f K is used to eliminate the influence of the reference input on the system. The above control methods were applied to the whole machine simulation platform of a certain type of wheel loader, and the random disturbance load of the measured under real working conditions was taken as input load. Under the conditions of no-load, half-load and full load, the control method has good smoothness and strong robustness. This paper has reference value for solving the inertial phase shift robust control of transmission under random disturbance load.
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