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Ma T.,Anhui University of Science and Technology | Ma T.,State Key Laboratory of Mechanics and Control of Mechanical Structures | Du F.,Anhui University of Science and Technology
Applied Mechanics and Materials | Year: 2012

A chaos particle swarm algorithm has been used to search for the optimal placement and size of the piezoelectric sensors and actuators (S/As) bonded on smart beams as well as the optimal feedback control gains. The criterion based on the minimization of stored and needed control energy was adopted for the optimization of the control system. The optimal distributions of the piezoelectric patches and feedback control gains based on specific controlled vibration modes have also been put forward. The results showed that the control effect could be significantly improved with optimized distribution of piezoelectric patches and gains. © (2012) Trans Tech Publications. Source


Wu Z.,Nanjing University of Aeronautics and Astronautics | Li L.,Shandong University | Hu X.,Nanjing University of Aeronautics and Astronautics | Song Y.,Nanjing University of Aeronautics and Astronautics | Song Y.,State Key Laboratory of Mechanics and Control of Mechanical Structures
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2013

To solve the problem of prediction of multi-axial fatigue life, a new thought and method of establishing multi-axial fatigue life model is proposed. The multi-axial fatigue life model is established by fitting and optimizing axial and multi-axial test data both. This method reduces the restrictions of the formation of multi-axial fatigue damage parameters and the type of multi-axial fatigue test data. On this basis, a new multi-axial fatigue damage parameter based on maximum shear strain amplitude and normal strain and stress on the plane of maximum shear strain amplitude is proposed. The establishing method of multi-axial fatigue life model is evaluated by the multi-axial fatigue test data of ZTC4 cast titanium alloy, pure titanium and BT9 titanium alloy. The result shows that the new method is feasible. The prediction ability of the establishing life model is almost within a factor of two scatter band. Source


Zhou L.,State Key Laboratory of Mechanics and Control of Mechanical Structures | Chen G.,State Key Laboratory of Mechanics and Control of Mechanical Structures
Journal of Vibroengineering | Year: 2015

Finite element modeling and active vibration control of a high-speed spinning flexible coupled electromechanical beam is investigated using a first-order approximation coupling (FOAC) model. Due to centrifugal forces caused by eccentricity in a spinning flexible beam, there exists coupling between axial and transverse vibration modes. The partial differential equations of motion of the beam governing this coupling are derived using Hamilton’s principle based on an FOAC model, and a finite element method for discretization is given. It is observed that the zero-order approximate coupling (ZOAC) model is valid for dynamic description of the flexible beam spinning at low speeds, but no longer valid at high speeds. However, the validity of FOAC model is confirmed at different speeds. Piezoelectric elements for active vibration control of the spinning flexible beam are analyzed and a velocity feedback controller is proposed. Simulation results demonstrate good performance of the proposed velocity feedback controller. © 2015, JVE INTERNATIONAL LTD. Source


Yang L.,Nanjing University of Aeronautics and Astronautics | Yang L.,State Key Laboratory of Mechanics and Control of Mechanical Structures | Wang L.,Lab Tech Support | Yu L.,Nanjing University of Aeronautics and Astronautics | Cheng H.,Nanjing University of Aeronautics and Astronautics
Journal of Engineered Fibers and Fabrics | Year: 2015

In order to study the influence of circular gap controlled by the tearing force on rescue parachute inflation performance, the Arbitrary Lagrange-Euler (ALE) coupling method is utilized to simulate the inflation process of the circular gap rescue parachute with fixed payload; the contact failure model of the open of circular gap was built by the sewing force of the sewing thread. The canopy structure model influenced by fabric permeability performance is proposed, and the differential pressure of permeable fabric is described in Ergun equation through the textile material permeability test. The numerical results calculated by LS-DYNA are compared with the results of airdrop test and the empirical method of parachute-payloads dynamics, and it is shown that the steady drag coefficient and transient shape during inflation are more consistent with the airdrop test results, and the dimensionless initial inflation time and the maximum equivalent opening shock are more realistic. The stress variations of each gore unity during inflation are investigated. The most dangerous time-space state point during inflation process was discovered. With the study of the influence of the circular gap structure of parachute on inflation performance, the numerical results show the circular gap structure can reduce the opening load and adjust the time of two inflation stages, which reduces the maximum effective stress in dangerous parts and improves the safety of canopy. © 2014, Association Nonwoven Fabrics Industry. All rights reserved. Source


He H.,Nanjing University of Aeronautics and Astronautics | He H.,State Key Laboratory of Mechanics and Control of Mechanical Structures | Ni L.,China Aviation Industry General Aircraft Co. | He C.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Zhendong Gongcheng Xuebao/Journal of Vibration Engineering | Year: 2014

This paper focuses on the finite element model updating of an airbag cushion landing system. First, a typical finite element model of an airbag cushion landing system is developed. Since the structure model and the airbag model is independent with each other, a systematic model updating strategy is proposed, and precisely for this reason the model updating of the recovery module structure and the airbag system are conducted individually. The impact responses at some key points are introduced to avoid the trouble caused by the difference between the sampling frequency and the trigger of the test and simulation. The confidence factor of the impact response is defined to evaluate the matching degree of the simulation results and testing results. The norm of the error between the testing data and the simulation results at the key points are defined as the updating objective, and the augmented radial basis functions are introduced to construct the agent model of the error norm. Since the minimum error norm will lead to ideal model parameters, model updating problem can be transformed into an optimization problem. The impact test and simulation of a typical airbag cushion landing system are conducted. The method presented in this paper is demonstrated through the comparison of the test results and the simulation results. Source

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