Kinetostatic Modeling of Fully Compliant Bistable Mechanisms Using Timoshenko Beam Constraint Model

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Guimin Chen ◽  
Fulei Ma
Keyword(s):  
Finite Element ◽  
Timoshenko Beam ◽  
Stable Equilibrium ◽  
Equilibrium Points ◽  
Beam Theory ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Shear Effects ◽  
Kinetostatic Model ◽  
Constraint Model

Fully compliant bistable mechanisms (FCBMs) have numerous applications in both micro- and macroscale devices, but the nonlinearities associated with the deflections of the flexible members and the kinetostatic behaviors have made it difficult to design. Currently, the design of FCBMs relies heavily on nonlinear finite element modeling. In this paper, an analytical kinetostatic model is developed for FCBMs based on the beam constraint model (BCM) that captures the geometric nonlinearities of beam flexures that undergo relatively small deflections. An improved BCM (i.e., Timoshenko BCM (TBCM)) is derived based on the Timoshenko beam theory in order to include shear effects in the model. The results for three FCBM designs show that the kinetostatic model can successfully identify the bistable behaviors and make reasonable predictions for the locations of the unstable equilibrium points and the stable equilibrium positions. The inclusion of shear effects in the TBCM model significantly improves the prediction accuracy over the BCM model, as compared to the finite element analysis (FEA) results.

A Finite Rotating Shaft Element Using Timoshenko Beam Theory

1980 ◽  
Vol 102 (4) ◽  
pp. 793-803 ◽  
Author(s):  
H. D. Nelson
Keyword(s):  
Timoshenko Beam ◽  
Beam Theory ◽  
Timoshenko Beam Theory ◽  
Internal Damping ◽  
Theory Analysis ◽  
Rotating Shaft ◽  
Element Analysis ◽  
Rotor Systems ◽  
The Finite Element Analysis ◽  
Rotating Shafts

The use of finite elements for simulation of rotor systems has received considerable attention within the last few years. The published works have included the study of the effects of rotatory inertia, gyroscopic moments, axial load, and internal damping; but have not included shear deformation or axial torque effects. This paper generalizes the previous works by utilizing Timoshenko beam theory for establishing the shape functions and, thereby including transverse shear effects. Internal damping is not included but the extension is straight forward. Comparison is made of the finite element analysis with classical dosed form Timoshenko beam theory analysis for nonrotating and rotating shafts.

Fretting Wear Modeling of Cylindrical Line Contact in Plane-Strain Borne by the Finite Element Method

2019 ◽  
Vol 86 (6) ◽  
Author(s):  
Huaidong Yang ◽  
Itzhak Green
Keyword(s):  
Finite Element ◽  
Plane Strain ◽  
Beam Theory ◽  
Fretting Wear ◽  
Partial Slip ◽  
Wear Volume ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Line Contacts ◽  
Theoretical Predictions

This is the first study to develop an empirical formulation to predict fretting wear (volume removal) under frictional conditions for plane-strain line contacts as borne out by the finite element analysis (FEA). The contact is between a deformable half-cylinder rubbing against a deformable flat block. The FEA is guided by detailed physical conceptions, with results that subsequently lead to the methodical modeling of fretting wear. The materials in contact are first set to steel/steel, then to Alloy617/Alloy617, and finally to copper/copper. Various coefficients of friction (COFs) and the Archard Wear Model are applied to the interface. Initially, pure elastic conditions are investigated. The theoretical predictions for the wear volume at the end of the partial slip condition in unidirectional sliding contact agree very well with the FEA results. The empirical formulation for the initial gross slip distance is constructed, again revealing results that are in good agreement with those obtained from the FEA for different materials and for various scales. The Timoshenko beam theory and the tangential loading analysis of a half elastic space are used to approximate the deflection of the half-cylinder and the flat block, respectively. That theory supports well the empirical formulation, matching closely the corresponding FEA results. The empirical formulation of the wear volume for a general cycle under fretting motion is then established. The results are shown to be valid for different materials and various COFs when compared with the FEA results. Finally, plasticity is introduced to the model, shown to cause two phenomena, namely junction growth and larger tangential deformations. Wear is shown to either increase or decrease depending on the combined influences of these two phenomena.

Finite element analysis of a Timoshenko beam traversed by a moving vehicle

2009 ◽  
Vol 223 (3) ◽  
pp. 231-243
Author(s):  
M Moghaddas ◽  
R Sedaghati ◽  
E Esmailzadeh ◽  
P Khosravi
Keyword(s):  
Finite Element ◽  
Timoshenko Beam ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Weak Form ◽  
Element Formulation ◽  
Governing Equations ◽  
Element Analysis ◽  
Moving Vehicle ◽  
The Difference

In this study the finite element formulation for the dynamics of a bridge traversed by moving vehicles is presented. The vehicle including the driver and the passenger is modelled as a half-car planner model with six degree of freedom, travelling on the bridge with constant velocity. The bridge is modelled as a uniform beam with simply supported end conditions that obeys the Timoshenko beam theory. The governing equations of motion are derived using the extended Hamilton principle and then transformed into the finite element format by using the weak-form formulation. The Newmark-β method is utilized to solve the governing equations and the results are compared with those reported in the literature. Furthermore, the maximum values of deflection for the Timoshenko and Euler—Bernoulli beams have been compared. The results illustrated that as the velocity of the vehicle increases, the difference between the maximum beam deflections in the two beam models becomes more significant.

Strength Design of a Mechanical Parking System

2014 ◽  
Vol 487 ◽  
pp. 385-388
Author(s):  
Bin Xu ◽  
Zhong Jian Yu ◽  
Yu Qing Yang ◽  
Tao Zhang
Keyword(s):  
Finite Element ◽  
Hot Spot ◽  
Beam Theory ◽  
Strength Properties ◽  
Element Analysis ◽  
Experimental Stress Analysis ◽  
The Finite Element Analysis ◽  
Parking System ◽  
Practical Engineering ◽  
Von Mises

Mechanical parking systems are widely used special electromechanical equipments. With the increasing interests on strength safety, it was becoming a hot spot to achieve its strength properties precisely. Based on Timoshenko beam theory, a mechanical parking system was simplified to a two dimensional model, and strength calculation was performed with analytical method. Furthermore, finite element method was adopted to calculate the strength properties of this mechanical parking system, and the maximum Von Mises and shear stress were approached. By comparison with experimental stress analysis, the finite element analysis was precise, which showed a potential application in practical engineering.

Interactive Graphics for the Analysis of Tires

1985 ◽  
Vol 13 (3) ◽  
pp. 127-146 ◽  
Author(s):  
R. Prabhakaran
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Approximate Solutions ◽  
Interactive Graphics ◽  
Element Analysis ◽  
Analysis Process ◽  
Physical Problems ◽  
The Finite Element Analysis ◽  
Analysis Computer ◽  
Discretization Technique

Abstract The finite element method, which is a numerical discretization technique for obtaining approximate solutions to complex physical problems, is accepted in many industries as the primary tool for structural analysis. Computer graphics is an essential ingredient of the finite element analysis process. The use of interactive graphics techniques for analysis of tires is discussed in this presentation. The features and capabilities of the program used for pre- and post-processing for finite element analysis at GenCorp are included.

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