scholarly journals Nonlinear dynamic characteristics of SMA gripper under bounded noise

2019 ◽  
Vol 83 ◽  
pp. 01010
Author(s):  
Xin-Miao Li ◽  
Zhi-Wen Zhu ◽  
Qing-Xin Zhang
Keyword(s):  
Constitutive Model ◽  
Dynamic Response ◽  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Vibration Amplitude ◽  
Random Disturbance ◽  
Bounded Noise ◽  
Nonlinear Dynamic Response ◽  
Nonlinear Dynamic Characteristics

A kind of constitutive model of SMA is proposed in this paper, and the nonlinear dynamic response of a SMA gripper under bounded noise is studied. The harmonic driving signals and the random disturbance made up of bounded noise. The dynamic model of the system is established by Hamilton principle. The numerical and experimental results show that there is stochastic resonance in the system; the system’s vibration amplitude reaches the most when the outside excitation is moderate.

Nonlinear dynamic characteristics and optimal control of MSMA actuator subjected to harmonic magnetic field and stochastic excitation

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1523-1529
Author(s):  
Benhy Ngouala ◽  
Fang Liu ◽  
Jia Xu ◽  
Zhi-Wen Zhu
Keyword(s):  
Magnetic Field ◽  
Dynamic Programming ◽  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Stochastic Perturbation ◽  
Stochastic Dynamic ◽  
Random Disturbance ◽  
Magnetic Shape Memory ◽  
Nonlinear Dynamic Characteristics

A novel magnetic shape memory alloy (MSMA) actuator is proposed in this paper, which has fast response speed and large deformation, and its nonlinear dynamic response and control are studied. A new differential term is developed to explain the MSMA’s stress-strain curves. The dynamic model of the MSMA actuator subjected to harmonic magnetic field and random disturbance is established, and its nonlinear dynamic characteristics are obtained. Finally, the stochastic dynamic programming control is introduced to enhance the drive accuracy. The results show that the perturbation plays an important role in the system’s dynamic response; dynamic programming control can improve the actuator’s accuracy in strong stochastic perturbation. These results will be helpful for the optimal design and development of MSMA actuators.

Bifurcation and Chaos of a Spur Gear Transmission System With Non-Uniform Wear

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Zhibo Geng ◽  
Ke Xiao ◽  
Junyang Li ◽  
Jiaxu Wang
Keyword(s):  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Operating Time ◽  
Spur Gear ◽  
Gear Transmission ◽  
Nonlinear Dynamic Model ◽  
Gear Backlash ◽  
Gear Transmission System ◽  
Nonlinear Dynamic Characteristics

Abstract In this study, a nonlinear dynamic model of a spur gear transmission system with non-uniform wear is proposed to analyze the interaction between surface wear and nonlinear dynamic characteristics. A quasi-static non-uniform wear model is presented, with consideration of the effects of operating time on mesh stiffness and gear backlash. Furthermore, a nonlinear dynamic model with six degrees-of-freedom is established considering surface friction, time-varying gear backlash, time-varying mesh stiffness, and eccentricity, and the Runge–Kutta method applied to solve this model. The bifurcation and chaos in the proposed dynamic model with the change of the operating time and the excitation frequency are investigated by bifurcation and spectrum waterfall diagrams to analyze the bifurcation characteristics and the dimensionless mesh force. It is found that surface wear is generated with a change in operating time and affects the nonlinear dynamic characteristics of the spur gear system. This study provides a better understanding of nonlinear dynamic characteristics of gear transmission systems operating under actual conditions.

Wave Motion Dynamic Analysis of Planar Frame Structures With Clearance Joints

2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Juntao Zhu ◽  
Tuanjie Li ◽  
Zuowei Wang ◽  
Hangjia Dong
Keyword(s):  
Numerical Method ◽  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Wave Motion ◽  
Continuous Wave ◽  
Fdtd Method ◽  
Frame Structures ◽  
Clearance Joints ◽  
Nonlinear Dynamic Characteristics

Abstract Due to kinematic function requirements, deployable structures inevitably have many clearance joints. The existence of clearance joints not only reduces the structural stiffness but also leads to complex nonlinear dynamic characteristics. This paper proposed a general numerical method based on the wave motion theory, which is able to analyze these complex nonlinear dynamic characteristics of frame structures with clearance joints. The dynamic model of frame structures with clearance joints is derived on the basis of continuous wave equations. The clearance joint is modeling by combining Lankarani and Nikravesh contact model with the Ambrósio friction model. The established dynamic model of frame structures is solved by the finite difference time domain (FDTD) method. A triangular frame structure with two clearance joints is taken as the numerical example for the verification of the proposed numerical method. Numerical results show that the longitudinal wave affects the distribution direction of contact positions and the transverse wave mainly affects the distribution range of contact positions. It has been also found that the introduction of torsional springs with reasonable pretension torque is able to significantly improve the distribution of contact positions and reduce state uncertainties of clearance joints in structural vibrations.

Dynamics of Composite Structures With Multiple Delaminations

2001 ◽  
Author(s):  
W. Lestari ◽  
H. Lou ◽  
S. Hanagud
Keyword(s):  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Nonlinear Dynamic ◽  
Composite Structures ◽  
Impact Damage ◽  
Structural Dynamic ◽  
Nonlinear Dynamic Response ◽  
Structural Dynamic Characteristics ◽  
Opening And Closing

Abstract The objective of this paper is to explore if changes in the structural dynamic response and structural dynamic characteristics can be used to identify the existence, location and magnitude of defects like a delamination or an impact damage, at the macroscale level, before they can grow to their critical sizes. Specifically dynamic response of composite structures, with delamination defects, is discussed in this paper. The experimental analysis is performed to capture the effects of nonlinearities on the dynamic response of a beam with multiple delaminations. To describe the opening and closing mode of the delaminated segments of the beam during the vibration, an analysis is performed by using a model with piecewise spring. Then, the nonlinear dynamic response is calculated.

Nonlinear Dynamic Characteristics of PZT/Polymer Gripper

2018 ◽  
Vol 26 (1) ◽  
pp. 79-84
Author(s):  
Jia Xu ◽  
Yi-Ran Li ◽  
Hai-Bo Wang ◽  
Zhi-Wen Zhu
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
Noise Intensity ◽  
Resonance Phenomenon ◽  
Dynamical Response ◽  
Stochastic Noise ◽  
Nonlinear Dynamic Model ◽  
Bounded Noise ◽  
Response Range ◽  
Nonlinear Dynamic Characteristics

A kind of PZT/polymer gripper is proposed in this paper and its nonlinear dynamic response in bounded noise is described. In this paper, a polymer piezoelectric material is applied in gripper to substitute the traditional PZT to improve the response range. Nonlinear differential items are introduced to interpret the hysteretic phenomena of the PZT/polymer piezoelectric composites material, and the nonlinear dynamic model of the PZT/polymer gripper in bounded noise is developed. The dynamic response of the system is obtained, and the bifurcation characteristics of the system are analyzed. The results of numerical simulation and experiments show that the stochastic noise intensity has important influence on the system's dynamical response, and the stochastic resonance phenomenon occurs with the stochastic noise intensity variety.

An Approximate Analytical Solution for Dynamic Response of a Large Nonlinear Rotor-Bearing System

2016 ◽  
Vol 693 ◽  
pp. 445-452
Author(s):  
Xiao Ying Liu ◽  
Cai Jing Yang ◽  
Li Ping Zhou ◽  
Yu Wang ◽  
Jia Sheng Wang
Keyword(s):  
Analytical Solution ◽  
Dynamic Response ◽  
Dynamic Model ◽  
Nonlinear Dynamic ◽  
Harmonic Balance Method ◽  
Rotating Machinery ◽  
Nonlinear Dynamic Response ◽  
Reduced Order ◽  
Rotor Bearing ◽  
Bearing System

Large nonlinear rotor-bearing system is an important structure in rotating machinery, such as NC machine. Due to the mass imbalance of the system, vibrations induced by centrifugal forces inevitably exist in rotating machinery. So, nonlinear dynamic response of a complex rotor-bearing system was dealt with in this paper. The system considered was modeled using the finite element method and has 124 DOFs (degrees of freedom). A linear reduction method was used and a reduced-order dynamic model of the system with two DOFs had been obtained. Harmonic balance method was applied to the reduced-order dynamic model of the system and an approximate analytical expression of the solution for nonlinear dynamic response of the system at steady state was derived. The analytical solution obtained from the reduced-order dynamic model of the system was compared with the numerical one obtained from the direct integration of the equations of motion of the original system.

Dynamic response of a historical armory building using the finite element model validated by the ambient vibration test

2018 ◽  
Vol 24 (22) ◽  
pp. 5472-5484 ◽  
Author(s):  
Ahmet Can Altunişik ◽  
Ali Fuat Genç ◽  
Murat Günaydin ◽  
Fatih Yesevi Okur ◽  
Olguhan Şevket Karahasan
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Element Model ◽  
Ambient Vibration ◽  
Nonlinear Material ◽  
Mode Shapes ◽  
Nonlinear Dynamic Response

In this paper, the aim was to determine the nonlinear dynamic response of historical masonry armory buildings using a validated finite element model. Eight ambient vibration tests were conducted on the building, using three different measurement test setups to extract the dynamic characteristics using the Enhanced Frequency Domain Decomposition method. A finite element model was constructed in ANSYS and the dynamic characteristics were obtained numerically. It can be seen that there is a good correlation between the mode shapes, but there are differences in natural frequencies with maximum values of 10.1%, 7.4% and 13.4% for first the three modes. To determine the nonlinear dynamic response, the validated finite element model was analyzed using the Kocaeli earthquake motion. The Drucker–Prager criterion and Willam–Warnke surface were considered for the nonlinear material models. At the end of the analyses, maximum displacements, principal stresses and strains are given in detail using contour diagrams. It is evident that the displacements show an increasing trend from the base to the top point of the building. Stresses occurred on the corners, openings and transition segments. In addition, crack distribution diagrams were drawn up to illustrate the stress accumulation points.

Complexity evaluation of nonlinear dynamic behavior of mechanisms with clearance joints by using the fractal method

2014 ◽  
Vol 228 (18) ◽  
pp. 3482-3495 ◽  
Author(s):  
Wuweikai Xiang ◽  
Shaoze Yan ◽  
Jianing Wu ◽  
Robert X Gao
Keyword(s):  
Dynamic Response ◽  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Correlation Dimension ◽  
Nonlinear Dynamic Response ◽  
Fractal Method ◽  
Motion Equations ◽  
Clearance Joints ◽  
Nonlinear Dynamic Characteristics ◽  
Crank Mechanism

Dynamic behavior of mechanisms with clearance joints often exhibits nonlinear dynamic characteristics due to the collisions between the journal and bearing. However, previous studies could not quantify the complexity of the dynamic response. In this paper, based on the Poincaré map and correlation dimension, a fractal method is proposed to evaluate the complexity of nonlinear dynamic response of mechanisms with clearance joints. Motion equations of mechanical systems with clearance joints are described. A slider–crank mechanism is employed to demonstrate the efficiency of the fractal method and to discuss the influence of the clearance size and crank speed on the complexity of the dynamic response.

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