scholarly journals Thermo-elastostatic analyzes of new dampers made of polymer springs with negative thermal expansion

2021 ◽  
Vol 1199 (1) ◽  
pp. 012056
Author(s):  
J Murín ◽  
V Goga ◽  
J Paulech ◽  
J Hrabovský ◽  
T Sedlár ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Thermal Expansion ◽  
Mathematical Models ◽  
Thermal Load ◽  
Negative Thermal Expansion ◽  
Active Damping ◽  
Artificial Muscles ◽  
The Finite Element Method ◽  
Additional Heat ◽  
Real Model

Abstract The article presents original results of research of the dampers with passive and semi-active damping using polymer springs (also artificial muscles or nylon springs) with negative thermal expansion. Passive damping can be ensured by the strong damping effects of polymer springs. Semi-active damping can be provided by heating the springs from an additional heat source. According to design such dampers, mathematical models for analytical elastostatic and thermoelastostatic analyzes of dampers for selected load cases are processed in the paper. The permissible values of mechanical and thermal load of the dampers are determined. The obtained results are verified by numerical analysis using the finite element method. The elastostatics of the passive damper and its damping functionality have been verified on a real model of the damper. The compiled mathematical models can be used in the design of polymer dampers as well as in their automatic control. Designed and analysed dampers can be used in smaller mobile or stationary systems such as scooters, small car kits and the like. The elastodynamic functionality of the dampers with passive and semiactive damping will be presented and discussed in our further paper.

Development of Stacked-Type Electrostatic Actuator Using Two Ribbon Films

2013 ◽  
Vol 25 (2) ◽  
pp. 324-332 ◽  
Author(s):  
Kazuo Okuda ◽  
◽  
Keiji Saneyoshi ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Reduction Rate ◽  
Measured Data ◽  
The Other ◽  
Artificial Muscles ◽  
Electrostatic Actuator ◽  
The Finite Element Method ◽  
Nonlinear Structural Analysis ◽  
Working Region

A new stacked-type electrostatic actuator with two ribbon films has been developed to be applied to artificial muscles. In this paper, spring characteristics of the actuator have been simulated and compared to measured data. There are two regions in spring characteristics of the actuator: one is the working region where the actuator contracts easily, and the other is the overload region where the actuator is extended only negligibly by the load. Spring characteristics of the actuator have been simulated by nonlinear structural analysis including the contact problem using the finite element method. It is understood that spring characteristics of working and overload regions can be improved by thinning the hinge and by thickening the electrode. The stroke of the actuator can be controlled, furthermore, by changing the length of the hinge. When the size of the actuator is reduced and actuators are integrated until they become the same volume, voltage applied to the actuator to generate the same force is reduced in proportion to the reduction rate while the actuator keeps the same spring characteristics and stroke.

Erosion Wear Resistance of CWS Laminated Ceramic Nozzles

2012 ◽  
Vol 538-541 ◽  
pp. 1915-1919
Author(s):  
Jian Xin Deng ◽  
Yang Yang Chen ◽  
You Qiang Xing
Keyword(s):  
Finite Element Method ◽  
Wear Resistance ◽  
Thermal Expansion ◽  
Wear Behavior ◽  
Erosion Wear ◽  
The Finite Element Method ◽  
Apparent Increase ◽  
Coal Water Slurry ◽  
Laminated Structures ◽  
Large Tensile Stress

In coal-water-slurry (CWS) boilers, the nozzle is eroded continuously by the abrasive action of the CWS, and there are high temperature and temperature gradient inside nozzle, which may cause large tensile stress and lead to an increased erosion wear of the nozzle. In this paper, Al2O3/(W,Ti)C+Al2O3/TiC laminated ceramics were developed to be used as nozzles in CWS boilers. The purpose is to reduce the tensile stresses at the nozzle during the CWS burning process. The value of the residual stresses, which arise from a mismatch between the coefficients of thermal expansion of the constituent phases and neighbouring layers, was calculated by means of the finite element method. The erosion wear behavior of the laminated nozzles was investigated and compared with an unstressed reference nozzle. Results showed that the laminated ceramic nozzles exhibited an apparent increase in erosion wear resistance over the unstressed reference one. It is suggested that laminated structures in ceramic nozzles is an effective way to improve their erosion wear resistance in industrial CWS boilers.

Finite Element Stress Analysis of a Class I Amalgam Restoration Subjected to Setting and Thermal Expansion

1978 ◽  
Vol 57 (5-6) ◽  
pp. 715-723 ◽  
Author(s):  
K.W.J. Wright ◽  
A.L. Yettram
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Expansion ◽  
Composite Structures ◽  
The Finite Element Method ◽  
Principal Stresses ◽  
Finite Element Stress Analysis ◽  
Amalgam Restoration ◽  
Class 1 ◽  
Set Up

Stress analyses are presented for a second mandibular premolar with a class 1 amalgam restoration. The effects of amalgam setting and thermal expansions are examined. An axisymmetric representation of the structure is used and the analyses are carried out by the finite element method. Lined and unlined restorations are compared with regard to the principal stresses set up in the composite structures and also the patterns of deformation incurred. The effects of various enamel and dentin stiffness combinations are also considered.

scholarly journals Heat Transfer Analysis in a Single Spool Gas Turbine by Using Calculated-Estimated Coefficients with the Finite Element Method

2020 ◽  
Vol 10 (23) ◽  
pp. 8328
Author(s):  
Geraldo Creci ◽  
Márcio Teixeira de Mendoça ◽  
João Carlos Menezes ◽  
João Roberto Barbosa
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Finite Element ◽  
Thermal Expansion ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
The Finite Element Method ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Expansion Behavior

In this paper, a calculation procedure is presented to estimate the heat transfer coefficients of a single spool gas turbine designed to generate 5 kN of thrust. These heat transfer coefficients are the boundary conditions which govern the heat interaction between the solid parts and the working fluid in the gas turbine. However, the calculation of these heat transfer coefficients is not a trivial task, since it depends on complex fluid flow conditions. Empirical correlations and assumptions have been used to find convective heat transfer coefficients over most components, including stator vanes, rotor blades, disc faces, and disc platforms. After defining the heat transfer coefficients, the finite element method was used to determine the temperature distribution in one eighth section of the gas turbine making use of the problem cyclic symmetry. Both static and rotating assemblies have been modeled. The results allowed the prediction of the thermal expansion behavior of the whole single spool gas turbine with special attention to the safety margin of clearances. Furthermore, having the temperature distribution defined, it is possible to calculate the thermal stresses in any mechanical component. Additionally, it is possible to specify suitable metallic alloys for achieving appropriate performance in every case. The structural integrity of all components was then assured with the temperature distribution and thermal expansion behavior under knowledge. Thus, the mechanical drawings could be released to manufacturing.

Effects of Thinned Multi-Stacked Wafer Thickness on Stress Distribution in the Wafer-on-a-Wafer (WOW) Structure

2009 ◽  
Vol 1156 ◽  
Author(s):  
Hideki Kitada ◽  
Nobuyuki Maeda ◽  
Koji Fujimoto ◽  
Kousuke Suzuki ◽  
Tomoji Nakamura ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Thermal Expansion ◽  
Adhesive Layer ◽  
The Finite Element Method ◽  
Key Factors ◽  
3 Dimensional ◽  
Structural Integration ◽  
Wafer Thickness ◽  
Low K

AbstractIn the trough silicon via (TSV) structure for 3-dimensional integration (3DI), large thermal-mechanical stress acts in the TSV caused by the mismatch in thermal expansion coefficient (CTE) of the TSV materials. In this study, the stress of multi-stacked thin silicon wafers composed of copper TSV and copper/low-k BEOL structure was analyzed by the finite element method (FEM), aiming to reduce the stress of TSV of 3D-IC. The results of sensitivity analysis using design of experiment (DOE) indicated that the thickness of the silicon and adhesive layer are the key factors for the structural integration of TSV design.

Study of Material’s Creep Relaxation Capability

2011 ◽  
Vol 121-126 ◽  
pp. 406-410
Author(s):  
Hong Jiang Chen ◽  
Yue Hai Wu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mathematical Models ◽  
System Failure ◽  
Test Results ◽  
The Finite Element Method ◽  
System Failures ◽  
Important Trend ◽  
Important Form ◽  
Element Method

Creep relaxation is an important form of system failure, how to understand and analyze the effect of creep relaxation, to solve system failures and improve economic efficiency are of great significance. The paper describe researches of creep relaxation , mathematical models and theories at home and abroad in detail, and introduce the finite element method applied in this field. By comparing with the mathematical models, finite element Methods with test results, improving current mathematical models and utilizing finite element method is an important trend.

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