Analysis of the Damping of Beams With Discontinuous Viscoelastic Damping Layer Using Integral Finite Elements

Volume 2 ◽  
2004 ◽  
Author(s):  
T. Liang ◽  
Qian Chen ◽  
S. Olutunde Oyadiji ◽  
Andrew Leung
Keyword(s):  
Finite Elements ◽  
Structural Dynamics ◽  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Viscoelastic Damping ◽  
Fe Model ◽  
Dynamics Analysis ◽  
Viscoelastic Composite ◽  
Constraint Damping ◽  
Damping Treatments

The damping performance of discontinuous constrained viscoelastic damping layer using Integral Finite Elements (IFE) are investigated in this paper. The IFE involves the dynamic analysis of Elastic-Viscoelastic Composite (EVC) structures with frequency-dependant material properties. EVC structures, which incorporate constrained viscoelastic damping treatment, are modelled using IFE’s and conventional FE’s together to deal with the discontinuous treatment of the constraint damping layers. This approach dramatically reduces the number of degrees of freedom of the FE model compared with conventional FE models. By using specialised algorithms developed for EVC structural dynamics analysis, IFE makes the estimation of the dynamic properties of the EVC structures an easy task similar to the structural dynamics analysis using conventional finite element method. Using an IFE model and the special algorithms, the damping performance of various designs of viscoelastic damping treatments are investigated at extremely low computational costs compared with the use of current commercial FE software packages. A guideline is introduced based on the results of the damping performance analysis for the structural design of viscoelastic damping treatments.

scholarly journals Exact and efficient interpolation using finite elements shape functions

2009 ◽  
pp. 307-331
Author(s):  
Gustavo H.C. Silva ◽  
Rodolphe Le Riche ◽  
Jérôme Molimard ◽  
Alain Vautrin
Keyword(s):  
Experimental Data ◽  
Finite Elements ◽  
Degrees Of Freedom ◽  
Mesh Size ◽  
Large Data ◽  
Fe Model ◽  
Shape Functions ◽  
Natural Choice ◽  
Data Points ◽  
Bounding Boxes

The comparison of finite elements (FE) and experimental data fields have become ever more prevalent in numerical simulations. Since FE and experimental data fields rarely match, the interpolation of one field into the other is a fundamental step of the procedure. When one of the fields comes from FE, using the existing FE mesh and shape functions is a natural choice to determine mesh degrees of freedom at data point coordinates. This makes no assumptions beyond those already made in the FE model. In this sense, interpolation using element shape functions is exact. However, crude implementations of this technique generally display a quadratic computation complexity with respect to mesh size and number of data points, which is impractical when large data fields must be compared repeatedly. This document aims at assembling existing numerical procedures to improve the interpolation efficiency. With a combination of cross-products, bounding-boxes and indexing methods, the resulting algorithm shows linear computation cost, providing significant improvement in efficiency.

The Effect of Membrane Load on the Usage of Berger’s Model in Electrostatically Actuated Pre-Stressed Circular Curved Micro Plates

2021 ◽  
Author(s):  
Lior Medina ◽  
Rami Eliasi ◽  
Rivka Gilat ◽  
Slava Krylov
Keyword(s):  
Finite Elements ◽  
Degrees Of Freedom ◽  
Mechanical Load ◽  
Fe Model ◽  
Buckling Modes ◽  
Reduced Order ◽  
Electrostatically Actuated ◽  
All Solutions ◽  
Convergence Study ◽  
Micro Plates

Abstract The effect of membrane load on the behaviour of axisymmetric bistable circular curved microplates on Berger’s based axisymmetric reduced order (RO) model, incorporating radial prestress, is studied. The model is first validated for a “mechanical” load, against a Föppl-von-Kármán’s RO model with twenty degrees of freedom (DOF), a finite differences (FD) solution and a finite elements (FE) model, serving as the reference. All solutions implement the “Riks” method to track possible unstable branches, which can swerve in due to the presence of higher buckling modes. A convergence study is carried out for the snap-through location and load, as well as for the critical elevation and prestress required for bistability. Based on validated results of the analysis, the reliability of the model for predicting the effect of prestress on the plate behaviour under nonlinear electrostatic load is then investigated while using FD solutions as the reference. The study furnishes a reliable expended RO model, which includes prestress on the as-fabricated curved plate. The resulting model can further be used to estimate the value of residual prestress, present in an electrostatically actuated curved plate, based on its response.

scholarly journals A Four-Parameter Iwan Model for Lap-Type Joints

2005 ◽  
Vol 72 (5) ◽  
pp. 752-760 ◽  
Author(s):  
Daniel J. Segalman
Keyword(s):  
Energy Dissipation ◽  
Structural Dynamics ◽  
Degrees Of Freedom ◽  
Joint Stiffness ◽  
Constitutive Models ◽  
Practical Method ◽  
Dynamics Analysis ◽  
Structural Dynamic ◽  
Length Scales ◽  
Experimental Values

The constitutive behavior of mechanical joints is largely responsible for the energy dissipation and vibration damping in built-up structures. For reasons arising from the dramatically different length scales associated with those dissipative mechanisms and the length scales characteristic of the overall structure, this physics cannot be captured through direct numerical simulation (DNS) of the contact mechanics within a structural dynamics analysis. The difficulties of DNS manifest themselves either in terms of Courant times that are orders of magnitude smaller than that necessary for structural dynamics analysis or as intractable conditioning problems. The only practical method for accommodating the nonlinear nature of joint mechanisms within structural dynamic analysis is through constitutive models employing degrees of freedom natural to the scale of structural dynamics. In this way, development of constitutive models for joint response is a prerequisite for a predictive structural dynamics capability. A four-parameter model, built on a framework developed by Iwan, is used to reproduce the qualitative and quantitative properties of lap-type joints. In the development presented here, the parameters are deduced by matching joint stiffness under low load, the force necessary to initiate macroslip, and experimental values of energy dissipation in harmonic loading. All the necessary experiments can be performed on real hardware or virtually via fine-resolution, nonlinear quasistatic finite elements. The resulting constitutive model can then be used to predict the force/displacement results from arbitrary load histories.

scholarly journals Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 444
Author(s):  
Guoning Si ◽  
Liangying Sun ◽  
Zhuo Zhang ◽  
Xuping Zhang
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Polyimide Film ◽  
Zebrafish Embryos ◽  
Multiple Degrees Of Freedom ◽  
Electrothermal Actuator ◽  
3D Space ◽  
Pick And Place

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

scholarly journals Designing of Drive Systems in the Aspect of the Desired Spectrum of Operation

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2562
Author(s):  
Tomasz Dzitkowski ◽  
Andrzej Dymarek ◽  
Jerzy Margielewicz ◽  
Damian Gąska ◽  
Lukasz Orzech ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Dynamic Parameters ◽  
Synthesis Algorithm ◽  
Moments Of Inertia ◽  
Driving System ◽  
Six Degrees Of Freedom ◽  
Resonance Frequencies ◽  
Drive Systems ◽  
Power Component

A method for selecting dynamic parameters and structures of drive systems using the synthesis algorithm is presented. The dynamic parameters of the system with six degrees of freedom, consisting of a power component (motor) and a two-speed gearbox, were determined, based on a formalized methodology. The required gearbox is to work in specific resonance zones, i.e., meet the required dynamic properties such as the required resonance frequencies. In the result of the tests, a series of parameters of the drive system, defining the required dynamic properties such as the resonance and anti-resonance frequencies were recorded. Mass moments of inertia of the wheels and elastic components, contained in the required structure of the driving system, were determined for the selected parameters obtained during the synthesis.

High Frequency Vibration Analysis of Automotive Body Panels with Damping Materials

2010 ◽  
Vol 36 ◽  
pp. 293-296
Author(s):  
Yoshio Kurosawa ◽  
Takao Yamaguchi
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
The Body ◽  
Viscoelastic Damping ◽  
Fe Model ◽  
Test Results ◽  
Automotive Body ◽  
Modal Damping ◽  
Practical Tool ◽  
Damping Materials

We have developed a technique for estimating vibrations of an automotive body structures with viscoelastic damping materials using large-scale finite element (FE) model, which will enable us to grasp and to reduce high-frequency road noise（200～500Hz）. In the new technique, first order solutions for modal loss factors are derived applying asymptotic method. This method saves calculation time to estimate modal damping as a practical tool in the design stages of the body structures. Frequency responses were calculated using this technique and the results almost agreed with the test results. This technique can show the effect of the viscoelastic damping materials on the automotive body panels, and it enables the more efficient layout of the viscoelastic damping materials. Further, we clarified damping properties of the automotive body structures under coupled vibration between frames and panels with the viscoelastic damping materials.

scholarly journals A collocatedC0finite element method: Reduced quadrature perspective, cost comparison with standard finite elements, and explicit structural dynamics

2014 ◽  
Vol 102 (3-4) ◽  
pp. 576-631 ◽  
Author(s):  
Dominik Schillinger ◽  
John A. Evans ◽  
Felix Frischmann ◽  
René R. Hiemstra ◽  
Ming-Chen Hsu ◽  
...  
Keyword(s):  
Finite Elements ◽  
Structural Dynamics ◽  
Cost Comparison ◽  
Element Method
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