Damping Improvement in Layered and Jointed Beams by Finite Element Analysis

2012 ◽  
Vol 505 ◽  
pp. 501-505 ◽  
Author(s):  
D.N. Thatoi ◽  
R.C. Mohanty ◽  
A.K. Acharya ◽  
B.K. Nanda
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Beam Theory ◽  
Element Model ◽  
Damping Capacity ◽  
Bernoulli Beam ◽  
Element Analysis ◽  
Linear Elastic ◽  
Mass Matrices ◽  
Euler Bernoulli Beam

Damping in built-up structures is produced by the energy dissipation due to micro-slip along the frictional interfaces. A finite element model of the linear elastic system has been formulated using the Euler-Bernoulli beam theory to investigate the damping phenomena in riveted connections. The discrete element system having two degrees of freedom per node representing v and has been used for the analysis. The generalized stiffness and mass matrices for this element has been derived. Extensive experiments have been conducted for the validation of the analysis. From this study, it is established that the damping capacity increases and the natural frequency decreases due to the joint effects.

Asymmetric Bifurcation of Initially Curved Nanobeam

2015 ◽  
Vol 82 (9) ◽  
Author(s):  
X. Chen ◽  
S. A. Meguid
Keyword(s):  
Symmetry Breaking ◽  
Degrees Of Freedom ◽  
Surface Elasticity ◽  
Beam Theory ◽  
Surface Effects ◽  
Beam Model ◽  
Bernoulli Beam ◽  
Reduced Order ◽  
Euler Bernoulli Beam ◽  
Bifurcation Behavior

In this paper, we investigate the asymmetric bifurcation behavior of an initially curved nanobeam accounting for Lorentz and electrostatic forces. The beam model was developed in the framework of Euler–Bernoulli beam theory, and the surface effects at the nanoscale were taken into account in the model by including the surface elasticity and the residual surface tension. Based on the Galerkin decomposition method, the model was simplified as two degrees of freedom reduced order model, from which the symmetry breaking criterion was derived. The results of our work reveal the significant surface effects on the symmetry breaking criterion for the considered nanobeam.

Developing a beam formulation for semi-crystalline two-way shape memory polymers

2020 ◽  
Vol 31 (12) ◽  
pp. 1465-1476
Author(s):  
Mohammad-Ali Maleki-Bigdeli ◽  
Majid Baniassadi ◽  
Kui Wang ◽  
Mostafa Baghani
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Beam Theory ◽  
Shape Memory Polymers ◽  
Bernoulli Beam ◽  
Von Karman ◽  
Von Kármán ◽  
Euler Bernoulli Beam ◽  
Beam Theories

In this research, the bending of a two-way shape memory polymer beam is examined implementing a one-dimensional phenomenological macroscopic constitutive model into Euler–Bernoulli and von-Karman beam theories. Since bending loading is a fundamental problem in engineering applications, a combination of bending problem and two-way shape memory effect capable of switching between two temporary shapes can be used in different applications, for example, thermally activated sensors and actuators. Shape memory polymers as a branch of soft materials can undergo large deformation. Hence, Euler–Bernoulli beam theory does not apply to the bending of a shape memory polymer beam where moderate rotations may occur. To overcome this limitation, von-Karman beam theory accounting for the mid-plane stretching as well as moderate rotations can be employed. To investigate the difference between the two beam theories, the deflection and rotating angles of a shape memory polymer cantilever beam are analyzed under small and moderate deflections and rotations. A semi-analytical approach is used to inspect Euler–Bernoulli beam theory, while finite-element method is employed to study von-Karman beam theory. In the following, a smart structure is analyzed using a prepared user-defined subroutine, VUMAT, in finite-element package, ABAQUS/EXPLICIT. Utilizing generated user-defined subroutine, smart structures composed of shape memory polymer material can be analyzed under complex loading circumstances through the two-way shape memory effect.

Finite Element Quarter Vehicle Suspension Model under Periodic Bump and Sinusoidal Road Excitation

2018 ◽  
Vol 880 ◽  
pp. 163-170
Author(s):  
Ștefan Cristian Castravete ◽  
Gabriel Cătălin Marinescu ◽  
Nicolae Dumitru ◽  
Oana Victoria Oţăt
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Finite Model ◽  
Vehicle Speed ◽  
Element Analysis ◽  
Car Suspension ◽  
The Finite Element Analysis ◽  
Road Excitation ◽  
Suspension Model

The paper studies the behavior of a quarter-car suspension model under periodic road excitation: sinusoidal and bump (trapezoidal shape) for a constant vehicle speed. A theoretical and a finite element model were developed. The theoretical model has two degrees of freedom and a modal and sinusoidal excitation was performed to compare with finite model analysis. The finite element analysis consists of three parts: preload, modal analysis and deterministic external excitation. The study consists of the analysis of forces, displacements and accelerations that are transmitted to the vehicle regarding their variation in time and frequency.

Electrothermally Tunable Bridge Resonator

2016 ◽  
Author(s):  
Amal Z. Hajjaj ◽  
Nouha Alcheikh ◽  
Abdallah Ramini ◽  
Md Abdullah Al Hafiz ◽  
Mohammad I. Younis
Keyword(s):  
Fundamental Frequency ◽  
Beam Theory ◽  
Element Model ◽  
Bernoulli Beam ◽  
Electrothermal Actuation ◽  
Wide Range ◽  
Simulation Results ◽  
Dc Current ◽  
Euler Bernoulli Beam ◽  
Good Agreement

This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator compressed by a force due to electrothermal actuation. We demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally, by passing a DC current through it. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared to the experimental data and to simulation results of a multi-physics finite-element model. A good agreement is found among all the results.

Analysis of bimorph piezoelectric beam energy harvesters using Timoshenko and Euler–Bernoulli beam theory

2012 ◽  
Vol 24 (2) ◽  
pp. 226-239 ◽  
Author(s):  
Gang Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Slenderness Ratio ◽  
Beam Theory ◽  
Bernoulli Beam ◽  
Energy Harvesters ◽  
Bernoulli Beam Theory ◽  
Spectral Finite Element ◽  
Euler Bernoulli Beam ◽  
Element Method

Single-degree-of-freedom lumped parameter model, conventional finite element method, and distributed parameter model have been developed to design, analyze, and predict the performance of piezoelectric energy harvesters with reasonable accuracy. In this article, a spectral finite element method for bimorph piezoelectric beam energy harvesters is developed based on the Timoshenko beam theory and the Euler–Bernoulli beam theory. Linear piezoelectric constitutive and linear elastic stress/strain models are assumed. Both beam theories are considered in order to examine the validation and applicability of each beam theory for a range of harvester sizes. Using spectral finite element method, a minimum number of elements is required because accurate shape functions are derived using the coupled electromechanical governing equations. Numerical simulations are conducted and validated using existing experimental data from the literature. In addition, parametric studies are carried out to predict the performance of a range of harvester sizes using each beam theory. It is concluded that the Euler–Bernoulli beam theory is sufficient enough to predict the performance of slender piezoelectric beams (slenderness ratio > 20, that is, length over thickness ratio > 20). In contrast, the Timoshenko beam theory, including the effects of shear deformation and rotary inertia, must be used for short piezoelectric beams (slenderness ratio < 5).

Testing and Modeling of Roll Levelling Process

2014 ◽  
Vol 611-612 ◽  
pp. 1753-1762 ◽  
Author(s):  
Elena Silvestre ◽  
Eneko Sáenz de Argandoña ◽  
Lander Galdos ◽  
Joseba Mendiguren
Keyword(s):  
Finite Element ◽  
High Strength Steels ◽  
Beam Theory ◽  
High Strength ◽  
Theoretical Models ◽  
Element Model ◽  
Forming Process ◽  
Element Analysis ◽  
Design Engineers ◽  
Ultra High Strength Steels

Roll levelling is a forming process used to remove the residual stresses and imperfections of metal strips by means of plastic deformations. During the process the metal fibres are subjected to cyclic tension-compression deformations leading to achieve flat product. The process is especially important to avoid final geometrical errors when coils are cold formed or when thick plates are cut by laser. In the last years, and due to the appearance of high strength materials such as Ultra High Strength Steels, machine design engineers are demanding a reliable tool for the dimensioning of the levelling facilities. In response to this demand, Finite Element Analysis and Analytical methods are becoming an important technique able to lead engineers towards facilities optimization through a deeper understanding of the process. Aiming to this study two different models have been developed to analyze the roll levelling operations: an analytical model and a finite element model. The FE-analysis was done using 2D-modelling assuming plane strain conditions. Differing settings, leveller configuration and materials were investigated. The one-dimensional analytical levelling model is based on classical beam theory to calculate the induced strain distribution through the strip, and hence the evolving elastic/plastic stress distribution. Both models provide a useful guide to process-sensitivities and are able to identify causes of poor leveller performance. The theoretical models have been verified by a levelling experimental prototype with 13 rolls at laboratory.

Control-Oriented Order Reduction of Finite Element Model

1993 ◽  
Vol 115 (4) ◽  
pp. 708-711 ◽  
Author(s):  
K. Harold Yae ◽  
Daniel J. Inman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Control Design ◽  
Element Model ◽  
Reduced Model ◽  
State Variables ◽  
Dynamics Modeling ◽  
Element Analysis

In the dynamics modeling of a structure, finite element analysis employs reduction techniques, such as Guyan’s reduction, that remove some of the “insignificant” physical coordinates, that is, degrees of freedom at a node point. Despite such reduction, the resultant model is still too large for control design. This warrants further reduction as is frequently done in control design by approximating a large dynamical system with a fewer number of state variables. A problem, however, arises because a model usually undergoes, before being reduced, some form of coordinate transformations that destroy the physical meanings of the states. To correct such a problem, we developed a method that expresses a reduced model in terms of a subset of the original states. The proposed method starts with a dynamic model that is originated and reduced in finite element analysis. The model is then converted to a state-space form, and reduced further by the internal balancing method. At this stage, being in the balanced coordinate system, the states in the reduced model have no apparent resemblance to those of the original model. Through another coordinate transformation that is developed in this paper, however, this reduced model is expressed by a subset of the original states, so that the states in the reduced model can be related to the degrees of freedom of the nodes in the original finite element model.

Curvature-Based Finite Element Method for Euler-Bernoulli Beams

2007 ◽  
Author(s):  
Y. L. Kuo ◽  
W. L. Cleghorn
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Transverse Displacement ◽  
Bernoulli Beam ◽  
Numerical Examples ◽  
Displacement Based ◽  
Curvature Distribution ◽  
Euler Bernoulli Beam ◽  
Element Method

This paper presents a new method called the curvature-based finite element method to solve Euler-Bernoulli beam problems. An approximated curvature distribution is selected first, and then the approximated transverse displacement is determined by double integrations. Four numerical examples demonstrate the validity of the method, and the results show that the errors are smaller than those generated by a conventional method, the displacement-based finite element method, for comparison based on the same number of degrees of freedom.

Rational Stress Limits and Load Factors for Finite Element Analyses in Pipeline Applications: Part I—Linear Elastic Stress Limit Development

2010 ◽  
Author(s):  
Bisen Lin ◽  
Richard C. Biel
Keyword(s):  
Finite Element ◽  
Equivalent Stress ◽  
Element Model ◽  
Element Analysis ◽  
Linear Elastic ◽  
Stress Limit ◽  
Load Factors ◽  
End Conditions ◽  
Von Mises Equivalent Stress ◽  
Von Mises

In this paper, a rational stress limit based on the von Mises equivalent stress is established for pipelines subjected to internal pressure. This stress limit is based on the ASME pipeline Code’s design margin for the service and location of the installation [1, 2]. These Codes are recognized by 49 CRF192 [5]. Both capped-end and open end conditions are considered. The single value of stress limits can be derived by classical hand calculations for use in assessing the results of a finite element analysis (FEA). Two application examples are presented showing studies done with the ABAQUS [3], a commercial (FEA) software. A stress limit was first found using classical hand calculations and verified by a simple finite element model. The linearized stresses at some critical locations were then compared to the established stress limit, and multiples, for the assessments of membrane, membrane plus bending, etc. stresses. This paper is not intended to revise or replace any provision of ASME B31.8 [2]. Instead, it provides a rational stress limit that may be used in the assessment of detailed FEA analyses of pipelines and the associated components.

LENGTH AND WIDTH EFFECTS OF METAL FILMS ON STRESS-INDUCED BENDING OF SURFACE MICROMACHINED CANTILEVER CURVED GRATING

2012 ◽  
Vol 19 (01) ◽  
pp. 1250001 ◽  
Author(s):  
JU-NAN KUO
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Plane Deformation ◽  
Beam Theory ◽  
Element Model ◽  
Metal Films ◽  
Width Ratio ◽  
Element Analysis ◽  
Close Relationship ◽  
Out Of Plane

In this study, the length and width effects of metal films on the stress-induced bending of a surface micromachined cantilever curved grating are systematically investigated. A characterization of cantilever curved gratings with various lengths and widths was conducted to observe out-of-plane deformation. A finite element model was established to analyze the deformation. Finite element analysis and experimental results indicate that the commonly used beam theory formula for predicting the deformation of surface micromachined cantilever curved gratings is not valid for these devices. Experiments show that the shape of a cantilever curved grating and residual stress have a close relationship. As the length increases, the residual stress of the metal increases, resulting in a larger out-of-plane deformation of the cantilever curved grating. The tip deflection gradually decreases as the length-to-width ratio of the cantilever curved grating increases. A more reliable shape design of metal films on the stress-induced bending of surface micromachined cantilever curved gratings can thus be achieved.

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