scholarly journals Buckling Electrothermal NEMS Actuators: Analytic Design for Very Slender Beams

Micro ◽  
2022 ◽  
Vol 2 (1) ◽  
pp. 54-67
Author(s):  
Richard Syms ◽  
Dixi Liu
Keyword(s):  
Nanoelectromechanical Systems ◽  
Euler Beam ◽  
Buckling Mode ◽  
Element Analysis ◽  
Closed Form Solutions ◽  
Analytic Approximations ◽  
Slender Beams ◽  
Beam Bending ◽  
The Common ◽  
Analytic Design

Analytic approximations are presented for the response of buckling-mode electrothermal actuators with very slender beams with a width-to-length ratio of W/L≤0.001 of the type found in nanoelectromechanical systems (NEMS). The results are found as closed-form solutions to the Euler beam bending theory rather than by an iterative numerical solution or a time-consuming finite element analysis. Expressions for transverse deflections and stiffness are presented for actuators with the common raised cosine and chevron pre-buckled shapes. The approximations are valid when the effects of bending dominate over those of axial compression. A few higher-order approximations are also presented for less slender beams with 0.001≤W/L≤0.01.

Limit Loads for Laterally Loaded I-Section Beams With Consideration of Shear

2003 ◽  
Vol 47 (02) ◽  
pp. 83-91
Author(s):  
L. Belenkiy ◽  
Y. Raskin
Keyword(s):  
Physical Model ◽  
Limit Load ◽  
Nonlinear Finite Element ◽  
Shear Forces ◽  
Element Analysis ◽  
Limit Loads ◽  
Closed Form Solutions ◽  
Engineering Technique ◽  
Laterally Loaded ◽  
The Web

The paper examines an effect of shear forces on limit load for I-section beams carrying later alloads. The problem is solve don the basis of a physical model, which enables one to take into account the effect of a resistance of beam flanges to the plastic shears train in the web of the beam. The physical model for the evaluation of limit loads was veriŽed using nonlinear finite element analysis. An engineering technique for the calculation of limit loads for shiphull beams subjected to large shear forces was developed using this model. As illustrative examples, the paper shows the application of the proposed technique to obtain closed-form solutions for the prediction of limit loads.

scholarly journals Effects of plies orientations and initial geometric imperfections on buckling strength of a composite stiffened panel

2018 ◽  
Vol 191 ◽  
pp. 00008
Author(s):  
Ikram Feddal ◽  
Abdellatif Khamlichi ◽  
Koutaiba Ameziane
Keyword(s):  
Stiffened Panel ◽  
Buckling Mode ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Stiffened Panels ◽  
Specific Strength ◽  
Euler Buckling ◽  
Buckling Behavior ◽  
Composite Stiffened Panel ◽  
Strength And Stiffness

The use of composite stiffened panels is common in several activities such as aerospace, marine and civil engineering. The biggest advantage of the composite materials is their high specific strength and stiffness ratios, coupled with weight reduction compared to conventional materials. However, any structural system may reach its limit and buckle under extreme circumstances by a progressive local failure of components. Moreover, stiffened panels are usually assembled from elementary parts. This affects the geometric as well as the material properties resulting in a considerable sensitivity to buckling phenomenon. In this work, the buckling behavior of a composite stiffened panel made from carbon Epoxy Prepregs is studied by using the finite element analysis under Abaqus software package. Different plies orientations sets were considered. The initial distributed geometric imperfections were modeled by means of the first Euler buckling mode. The nonlinear Riks method of analysis provided by Abaqus was applied. This method enables to predict more consistently unstable geometrically nonlinear induced collapse of a structure by detecting potential limit points during the loading history. It was found that plies orientations of the composite and the presence of geometric imperfections have huge influence on the strength resistance.

Spring constants of filament-wound composite circular rings

2001 ◽  
Vol 215 (2) ◽  
pp. 211-226 ◽  
Author(s):  
P C Tse ◽  
S R Reid ◽  
S P Ng
Keyword(s):  
Three Dimensional ◽  
Element Analysis ◽  
Closed Form Solutions ◽  
Composite Ring ◽  
Filament Wound ◽  
Dimensional Finite Element ◽  
Filament Wound Composite ◽  
Circular Rings ◽  
Three Dimensional Finite Element ◽  
Wound Composite

Closed-form solutions from complementary strain energy are derived for the spring stiffnesses of mid-surface symmetric, filament-wound, composite circular rings under unidirectional loading. A three-dimensional finite element analysis (FEA) including the effects of transverse shear has also been applied to study the problem. Four > 45° and four > 75° E-glass/epoxy composite rings of odd numbers of covers were tested. Comparisons of the results obtained from the two methods with experimental data are made and the results are found to be in good agreement. The FEA prediction of stiffness is always higher than the theoretical result. The relationships between the spring stiffnesses and the winding angles and geometry of the filament-wound composite ring are considered and discussed.

Validation of Nitinol SMA Characteristics Using Finite Element Analysis and Closed Form Solutions

2013 ◽  
Vol 856 ◽  
pp. 147-152
Author(s):  
S.H. Adarsh ◽  
U.S. Mallikarjun
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Fe Analysis ◽  
Element Analysis ◽  
Complex Behaviour ◽  
Closed Form Solutions

Shape Memory Alloys (SMA) are promising materials for actuation in space applications, because of the relatively large deformations and forces that they offer. However, their complex behaviour and interaction of several physical domains (electrical, thermal and mechanical), the study of SMA behaviour is a challenging field. Present work aims at correlating the Finite Element (FE) analysis of SMA with closed form solutions and experimental data. Though sufficient literature is available on closed form solution of SMA, not much detail is available on the Finite element Analysis. In the present work an attempt is made for characterization of SMA through solving the governing equations by established closed form solution, and finally correlating FE results with these data. Extensive experiments were conducted on 0.3mm diameter NiTinol SMA wire at various temperatures and stress conditions and these results were compared with FE analysis conducted using MSC.Marc. A comparison of results from finite element analysis with the experimental data exhibits fairly good agreement.

Analyses of Full-Scale Tank Car Shell Impact Tests

2007 ◽  
Author(s):  
Y. H. Tang ◽  
H. Yu ◽  
J. E. Gordon ◽  
M. Priante ◽  
D. Y. Jeong ◽  
...  
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Three Dimensional ◽  
Full Scale ◽  
Collision Dynamics ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Closed Form Solutions

This paper describes analyses of a railroad tank car impacted at its side by a ram car with a rigid punch. This generalized collision, referred to as a shell impact, is examined using nonlinear (i.e., elastic-plastic) finite element analysis (FEA) and three-dimensional (3-D) collision dynamics modeling. Moreover, the analysis results are compared to full-scale test data to validate the models. Commercial software packages are used to carry out the nonlinear FEA (ABAQUS and LS-DYNA) and the 3-D collision dynamics analysis (ADAMS). Model results from the two finite element codes are compared to verify the analysis methodology. Results from static, nonlinear FEA are compared to closed-form solutions based on rigid-plastic collapse for additional verification of the analysis. Results from dynamic, nonlinear FEA are compared to data obtained from full-scale tests to validate the analysis. The collision dynamics model is calibrated using test data. While the nonlinear FEA requires high computational times, the collision dynamics model calculates gross behavior of the colliding cars in times that are several orders of magnitude less than the FEA models.

Optimization Design for Rotor Structure of Brushless Doubly Fed Machine

2012 ◽  
Vol 588-589 ◽  
pp. 420-423
Author(s):  
Xiu Ping Wang ◽  
Feng Ge Zhang ◽  
Xiao Ping Zhu ◽  
Guang Long Jia
Keyword(s):  
Finite Element Analysis ◽  
Agricultural Production ◽  
Optimization Design ◽  
Rapid Progress ◽  
Element Analysis ◽  
Design Program ◽  
The Common ◽  
Doubly Fed ◽  
Doubly Fed Machine ◽  
Rotor Structure

Brushless doubly fed machine (BDFM) has rapid progress in recent years, rotor modulation capability is still the role factor which limits the popularization and application. Rotor structure is designed derived from the common reluctance in this paper, finite element analysis(FEA) is used for the optimization of the rotor. By studying the optimization comparatively, design program of rotor structure can be obtained, which shows great feasibility in industrial and agricultural production.

scholarly journals The Linear Hygroscopic Expansion Coefficient of Cement-Based Materials and Its Determination

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Depeng Chen ◽  
Qilin Zhu ◽  
Zhifang Zong ◽  
Tengfei Xiang ◽  
Chunlin Liu
Keyword(s):  
Finite Element ◽  
Drying Shrinkage ◽  
Simple Calculation ◽  
Thermal Shrinkage ◽  
Element Analysis ◽  
Concrete Shrinkage ◽  
Temperature Load ◽  
Cement Based Materials ◽  
The Common ◽  
Inversion Analysis

A crack caused by shrinkage could remarkably increase the permeability, heavily deteriorate the durability, and heavily deteriorate the service life of a concrete structure. However, different forms of thermal shrinkage can be predicted by directly applying a temperature load on a node. The prediction of moisture-induced stresses in cement-based materials by using the common finite element method (FEM) software is a big challenge. In this paper, we present a simple numerical calculation approach by using the proposed coefficient of hygroscopic expansion (CHE) to predict the moisture-induced deformation of concrete. The theoretical calculation formula of the linear CHE (LCHE) of cement-based material was deduced based on the Kelvin–Laplace equation and the Mackenzie equation. The hygroscopic deformation of cement mortar was investigated by inversion analysis; based on the results, the LCHE could be determined. Moreover, a case analysis of the application of LCHE to concrete is also conducted. The simulated results of concrete shrinkage were close to the experimental ones. As a whole, it is feasible to predict the drying shrinkage of concrete through simple calculation by using the proposed LCHE, which is also beneficial to the direct application of moisture loads on nodes in finite element analysis (FEA).

scholarly journals Dynamic Finite Element Analysis of Bending-Torsion Coupled Beams Subjected to Combined Axial Load and End Moment

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Mir Tahmaseb Kashani ◽  
Supun Jayasinghe ◽  
Seyed M. Hashemi
Keyword(s):  
Finite Element ◽  
Convergence Rates ◽  
Nonlinear Eigenvalue Problem ◽  
Analytical Data ◽  
Compressive Force ◽  
Weighted Residual Method ◽  
Element Analysis ◽  
Closed Form Solutions ◽  
Dynamic Finite Element ◽  
Coupled Beams

The dynamic analysis of prestressed, bending-torsion coupled beams is revisited. The axially loaded beam is assumed to be slender, isotropic, homogeneous, and linearly elastic, exhibiting coupled flexural-torsional displacement caused by the end moment. Based on the Euler-Bernoulli bending and St. Venant torsion beam theories, the vibration and stability of such beams are explored. Using the closed-form solutions of the uncoupled portions of the governing equations as the basis functions of approximation space, the dynamic, frequency-dependent, interpolation functions are developed, which are then used in conjunction with the weighted residual method to develop the Dynamic Finite Element (DFE) of the system. Having implemented the DFE in a MATLAB-based code, the resulting nonlinear eigenvalue problem is then solved to determine the coupled natural frequencies of illustrative beam examples, subjected to various boundary and load conditions. The proposed method is validated against limited available experimental and analytical data, those obtained from an in-house conventional Finite Element Method (FEM) code and FEM-based commercial software (ANSYS). In comparison with FEM, the DFE exhibits higher convergence rates and in the absence of end moment it produces exact results. Buckling analysis is also carried out to determine the critical end moment and compressive force for various load combinations.

A Non-Prismatic Beam Element for the Optimization of Flexure Mechanisms

2020 ◽  
Author(s):  
Koen Dwarshuis ◽  
Ronald Aarts ◽  
Marcel Ellenbroek ◽  
Dannis Brouwer
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Range Of Motion ◽  
Beam Element ◽  
Precision Engineering ◽  
Element Analysis ◽  
Leaf Springs ◽  
Prismatic Beam ◽  
The Common ◽  
Flexure Joints

Abstract Flexure joints are rapidly gaining ground in precision engineering because of their predictable behavior. However the range of motion of flexure joints is limited due to loss of support stiffness in deformed configurations. Most of the common flexure joints consist of prismatic leaf springs. This paper presents a simple non-prismatic beam formulation that can be used for the efficient modelling of non-prismatic leaf springs. The resulting stiffness and stress computed by the non-prismatic beam element are compared to the results of a finite element analysis. The paper shows that the support stiffness of two typical flexure joints can be increased up to a factor of 1.9 by using non-prismatic instead of prismatic leaf springs.

Research on Deforming Law of Beam Structure

2011 ◽  
Vol 101-102 ◽  
pp. 1114-1118
Author(s):  
Feng Xu
Keyword(s):  
Concrete Beam ◽  
Plain Concrete ◽  
Bending Test ◽  
Damage Effect ◽  
Analysis Software ◽  
Beam Structure ◽  
Element Analysis ◽  
New Methods ◽  
Concrete Damage ◽  
Beam Bending

The equations of damage evolution of cross-section and the deflection deformation of concrete beam were established. Through the plain concrete beam bending test, the formula for calculating the deflection was verified. It is proved that the formula established in this paper is more accurate than the equation that doesn’t consider the damage effect. The concrete beam was modelled and analyzed by means of finite element analysis software, and comparison was carried out between the numerical simulation result and the experimental data. On the basis, new methods and ideas about concrete-damage were proposed.

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