Dynamic Analysis of a Flexible Manipulator With Passive Constrained Layer Damping

2003 ◽  
Author(s):  
J. Q. Zou ◽  
E. H. K. Fung ◽  
H. W. J. Lee
Keyword(s):  
Degrees Of Freedom ◽  
Ritz Method ◽  
Vertical Plane ◽  
Flexible Manipulator ◽  
Constrained Layer Damping ◽  
Shape Functions ◽  
Lagrange’S Equation ◽  
Highly Nonlinear ◽  
The Time Domain ◽  
Passive Constrained Layer Damping

This paper studies the vibration behavior of a flexible manipulator with passive constrained layer damping (PCLD) treatment. The manipulator rotates in a vertical plane and carries an end mass. Due to the highly nonlinear and coupled characteristics of the beam with PCLD treatment, “relative description” method is used to define the motions of the manipulator system. Using Lagrange’s equation and Rayleigh-Ritz method, the dynamic model of the manipulator is obtained and its vibration response is analyzed in the time domain. By assuming finite element shape functions as the displacement shape functions and using the complex damping model for the visco-elastic material (VEM) layer, the number of degrees of freedom of the system or the model dimension is greatly reduced. Numerical simulations show that the VEM not only reduces the amplitude of the elastic deflection but also quickly attenuates the vibration to zero. Also, it is confirmed that the geometry and physical properties of the PCLD treatment have significant effects on the dynamic response of the manipulator.

A Computational Optimal Control Approach to the Design of a Flexible Rotating Beam With Active Constrained Layer Damping

Aerospace ◽  
2004 ◽  
Author(s):  
Y. C. E. Lee ◽  
E. H. K. Fung ◽  
J. Q. Zou ◽  
H. W. J. Lee
Keyword(s):  
Optimal Control ◽  
Coordinate System ◽  
Control Voltage ◽  
Constrained Layer Damping ◽  
Shape Functions ◽  
Control Parametrization ◽  
Highly Nonlinear ◽  
Active Constrained Layer Damping ◽  
Passive Constrained Layer Damping ◽  
Active Constrained Layer

In this paper, a computational approach is adopted to solve the optimal control and optimal parameter selection problems of a rotating flexible beam fully covered with active constrained layer damping (ACLD) treatment. The beam rotates in a vertical plane under the gravitational effect with variable angular velocity and carries an end mass. Tangent coordinate system and the moving coordinate system are used in the system modeling. Due to the highly nonlinear and coupled characteristics of the system, a relative description method is used to represent the motion of the beam and the motion equations are set up by using relative motion variables. Finite element shape functions of a cantilever beam [1] are used as the displacement shape functions in this study. Lagrangian formulation and Raleigh-Ritz approach [2] are employed to derive the governing equations of motion of the nonlinear time-varying system. The problem is posed as a continuous-time optimal control problem. The control function parameters are the control gains. The two system parameters are the thickness of the constraining layer and the viscoelastic material layer. The software package MISER3.2, which is based on the Control Parametrization and the Control Parametrization Enhancing Transform (CPET) techniques is used to solve the combined problems. The optimal solution takes the end deflection, control voltage and the total weight into account. Results show that substantial improvements are obtained with ACLD as compared to the passive constrained layer damping (PCLD) treatment.

Damping Characteristics of a Cantilever Plate Using Permanent Magnetic Constrained Layer Damping Strip Treatment

2012 ◽  
Vol 450-451 ◽  
pp. 466-471
Author(s):  
Ming Li ◽  
Hui Ming Zheng
Keyword(s):  
Ritz Method ◽  
Constrained Layer Damping ◽  
Structural Vibrations ◽  
Torsional Mode ◽  
Calculation Of Parameters ◽  
New Class ◽  
Damping Characteristics ◽  
Special Cases ◽  
Cantilever Rectangular Plate ◽  
Passive Constrained Layer Damping

Significant improvement of damping characteristics can be achieved by using the new class of magnetic constrained layer damping treatment (MCLD). This paper presents the damping properties of the first and second torsional mode for a five-layer cantilever rectangular plate treated with partial MCLD. The Rayleigh-Ritz method and Hamilton’s principle are employed in the analysis. We have chosen both single and segmented patches with different sizes. It can be observed that for the two modes single-patched MCLD treatment induces less improvement of damping characteristics especially for the short patch. The effects of calculation of parameters like placement strategies of discrete patches, the length of patches are analyzed and discussed. The results obtained from analytical show that the optimum location of the patch, for the torsional mode, is at edge of the plate. Favorable comparisons with the conventional passive constrained layer damping treatment (PCLD) on various special cases of the problem are obtained. The results demonstrate MCLD treatment still improvements over PCLD in damping structural vibrations.

Lagrangian Formulation of Rotating Beam With Active Constrained Layer Damping in Time Domain Analysis

2004 ◽  
Vol 126 (2) ◽  
pp. 359-364 ◽  
Author(s):  
E. H. K. Fung ◽  
J. Q. Zou ◽  
H. W. J. Lee
Keyword(s):  
Elastic Material ◽  
Time Domain ◽  
Loss Factor ◽  
Degrees Of Freedom ◽  
Ritz Method ◽  
Lagrangian Formulation ◽  
Constrained Layer Damping ◽  
Rotating Beam ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer

In this paper, Lagrangian formulation of a horizontal rotating beam with active constrained layer damping (ACLD) treatment is presented. The problem is approached by the Rayleigh-Ritz method. By assuming modal functions as the displacement shape functions and using effective damping model of the visco-elastic material (VEM) layer, the number of degrees of freedom of the system is greatly reduced. The damping of the visco-elastic material is characterized by a shear (storage) modulus and a loss factor. Also the dynamic behavior of the rotating ACLD beam is analyzed in the time domain. The effects of control gains, shear modulus and loss factor of the VEM on the dynamic response are also investigated.

scholarly journals Treating the Solid Pendulum Motion by the Large Parameter Procedure

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
A. I. Ismail
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Vertical Plane ◽  
The Body ◽  
Large Parameter ◽  
Lagrange’S Equation ◽  
External Moment ◽  
Dynamical Description ◽  
Quasi Linear System

In this paper, we consider the dynamical description of a pendulum model consists of a heavy solid connection to a nonelastic string which suspended on an elliptic path in a vertical plane. We suppose that the dimensions of the solid are large enough to the length of the suspended string, in contrast to previous works which considered that the dimensions of the body are sufficiently small to the length of the string. According to this new assumption, we define a large parameter ε and apply Lagrange’s equation to construct the equations of motion for this case in terms of this large parameter. These equations give a quasi-linear system of second order with two degrees of freedom. The obtained system will be solved in terms of the generalized coordinates θ and φ using the large parameter procedure. This procedure has an advantage over the other methods because it solves the problem in a new domain when fails all other methods for solving the problem in such a domain under these conditions. It is one of the most important applications, when we study the slow spin motion of a rigid body in a Newtonian field of force under an external moment or the rotational motion of a heavy solid in a uniform gravity field or the gyroscopic motions with a sufficiently small angular velocity component about the major or the minor axis of the ellipsoid of inertia. There are many applications of this technique in aerospace science, satellites, navigations, antennas, and solar collectors. This technique is also useful in all perturbed problems in physics and mechanics, for example, the perturbed pendulum motions and the perturbed mechanical systems. The results of this paper also are useful in moving bridges and the swings. For satisfying the validation of the obtained solutions, we consider numerical considerations by one of the numerical methods and compare the obtained analytical and numerical solutions.

Experimental Studies on Active Vibration Control of a Beam Using Hybrid Active∕Passive Constrained Layer Damping Treatments

2005 ◽  
Vol 127 (5) ◽  
pp. 515-518 ◽  
Author(s):  
Pankaj K. Langote ◽  
P. Seshu
Keyword(s):  
Piezoelectric Materials ◽  
Active Vibration Control ◽  
Experimental Studies ◽  
Time Domain Analysis ◽  
Constrained Layer Damping ◽  
Active Vibration ◽  
The Time Domain ◽  
Damping Treatments ◽  
Passive Constrained Layer Damping ◽  
Hybrid Damping

Hybrid damping designs with active piezoelectric materials and passive viscoelastic materials (VEMs) combine the advantages of both active and passive constrained layer damping treatments. In this study, experiments have been conducted on nine systems viz., bare beam, active damping (AD), passive constrained layer damping (PCLD—three variants) and hybrid active∕passive constrained layer damping (Hybrid AD∕PCLD—four variants). Based on the time domain analysis of these systems, it is shown that the “best” performance is obtained using a hybrid damping configuration wherein the VEM and the piezoelectric layers are acting separately.

scholarly journals Initiating a Mathematical Model for Prediction of 6-DOF Motion of Planing Crafts in Regular Waves

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Parviz Ghadimi ◽  
Abbas Dashtimanesh ◽  
Yaser Faghfoor Maghrebi
Keyword(s):  
Mathematical Model ◽  
Time Domain ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Vertical Plane ◽  
Time Domain Simulation ◽  
Regular Waves ◽  
Computer Simulation Program ◽  
The Time Domain ◽  
The Mathematical Model

Nowadays, most of the dynamic research on planing ships has been directed towards analyzing the ships motions in either 3-DOF (degrees of freedom) mode in the longitudinal vertical plane or in 3-DOF or 4-DOF mode in the lateral vertical plane. For this reason, the current authors have started a research program of describing the dynamic behavior of planing ships in a 6-DOF mathematical model. This program includes the developing of a 6-DOF computer simulation program in the time domain. This type of simulation can be used for predicting the response of these planing vessels to the environmental disturbances during high-speed sailing. In this paper, the development of the mathematical model will be presented. Furthermore, a discussion will be offered about the use of these static contributions in a time domain simulation for modeling the behavior of planing crafts in regular waves.

scholarly journals A Genetic Algorithm based Neuro-Fuzzy Controller for Unmanned Aerial Vehicle Control

2022 ◽  
Vol 13 (1) ◽  
pp. 0-0
Keyword(s):  
Genetic Algorithm ◽  
Unmanned Aerial Vehicle ◽  
Degrees Of Freedom ◽  
Fuzzy Inference ◽  
Fuzzy Controller ◽  
Vertical Plane ◽  
Inference System ◽  
Neuro Fuzzy ◽  
Highly Nonlinear ◽  
Aerial Vehicle

In this paper a self-tuning Adaptive Neuro-fuzzy Inference System (ANFIS) Controller by Genetic Algorithm (GA) applied to trajectory tracking task of Unmanned Aerial Vehicle (UAV) is studied. The quadrotor was chosen due to its simple mechanical structure; nevertheless, these types of aircraft are highly nonlinear. A model of a non-linear closed-loop dynamic model of three degrees of freedom (3-DOF) quadrotor is developed and implemented. Intelligent control such as fuzzy logic is a suitable choice for controlling nonlinear systems. The ANFIS Controller is used to reproduce the desired trajectory of the quadrotor in 2-D Vertical plane and the GA algorithm aims is to facilitate convergence to the ANFIS’s optimal parameters in order to reduce learning errors and improve the quality of the controller. The performance of the ANFIS-GA controller is compared with a ANFIS and a conventional PID controller. Simulation results confirm the advantages of the proposed controller and approve better performance.

scholarly journals Higher Order Multiscale Finite Element Method for Heat Transfer Modeling

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3827
Author(s):  
Marek Klimczak ◽  
Witold Cecot
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Higher Order ◽  
Shape Functions ◽  
Multiscale Finite Element Method ◽  
Multiscale Finite Element ◽  
Steady State Heat ◽  
Steady State Heat Transfer

In this paper, we present a new approach to model the steady-state heat transfer in heterogeneous materials. The multiscale finite element method (MsFEM) is improved and used to solve this problem. MsFEM is a fast and flexible method for upscaling. Its numerical efficiency is based on the natural parallelization of the main computations and their further simplifications due to the numerical nature of the problem. The approach does not require the distinct separation of scales, which makes its applicability to the numerical modeling of the composites very broad. Our novelty relies on modifications to the standard higher-order shape functions, which are then applied to the steady-state heat transfer problem. To the best of our knowledge, MsFEM (based on the special shape function assessment) has not been previously used for an approximation order higher than p = 2, with the hierarchical shape functions applied and non-periodic domains, in this problem. Some numerical results are presented and compared with the standard direct finite-element solutions. The first test shows the performance of higher-order MsFEM for the asphalt concrete sample which is subject to heating. The second test is the challenging problem of metal foam analysis. The thermal conductivity of air and aluminum differ by several orders of magnitude, which is typically very difficult for the upscaling methods. A very good agreement between our upscaled and reference results was observed, together with a significant reduction in the number of degrees of freedom. The error analysis and the p-convergence of the method are also presented. The latter is studied in terms of both the number of degrees of freedom and the computational time.

Dynamic Simulation of Blood Flow Effects on Flexible Manipulators During Intra-Cardiac Procedures on the Beating Heart

2011 ◽  
Author(s):  
A. Salimi ◽  
J. Mohammadpour ◽  
K. Grigoriadis ◽  
N. V. Tsekos
Keyword(s):  
Blood Flow ◽  
Degrees Of Freedom ◽  
Beating Heart ◽  
Flexible Manipulator ◽  
External Disturbances ◽  
Actuation System ◽  
Cardiac Procedures ◽  
Rigid Body Model ◽  
Flow Effects ◽  
Valve Implantation

In this paper, we develop a numerical mixed flexible-rigid body model to take into account the effects of the external disturbances acting on a flexible manipulator secondary to the oscillatory transmitral blood flow in the left ventricle. The manipulator is made of a flexible rubber-like material to further extend the surgical robotic-based catheters’ degrees of freedom and steer-ability in beating-heart prosthetic aortic valve implantation procedure. Along with the developed numerical model, a detailed description of the catheter’s mechanical architecture and the actuation system is also provided. Necessity of employing such a model for the designed system is clearly justified using simulation studies.

Experimental evaluation of time-varying impulse shaping with a two-link flexible manipulator

Robotica ◽  
1996 ◽  
Vol 14 (3) ◽  
pp. 339-345 ◽  
Author(s):  
Jung-Keun Cho ◽  
Youn-Sik Park
Keyword(s):  
Vibration Reduction ◽  
Vertical Plane ◽  
Joint Stiffness ◽  
Flexible Manipulator ◽  
Input Shaping ◽  
Time Varying ◽  
Modal Properties ◽  
Revolute Joints ◽  
Point Motion ◽  
Point To Point

SUMMARYIn the authors' previous paper,10 an input shaping method was presented to reduce motion-induced vibrations effectively for various classes of flexible systems. In this paper, the effectiveness of the shaping method is experimentally demonstrated with a two-link flexible manipulator systemThe manipulator for experiments includes two revolute joints and two flexible links, and moves on a vertical plane under gravity. An analytic model is developed considering the flexibility of the system and its joint stiffness in order to derive an appropriate estimation of dynamic modal properties. The input shaping method used in this work utilizes time-varying modal properties obtained from the model instead of the conventional input shaping method which employs time-invariant modal properties. A point-to-point motion is tested in order to show the effectivess of the proposed shaping method in vibration reduction during and after a given motion. The given reference trajectories are shaped to suppress the motion induced vibration. The test results demonstrate that the link vibration can be greatly suppressed during and after a motion, and the residual vibration reduction was observed more than 90% by employing this time-varying impulse shaping technique.

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