Effects of Temperature Boundary Conditions on SMA Actuator Performance Using a Fully Coupled Thermomechanical Model

2011 ◽  
Author(s):  
Nicole Lewis ◽  
Stefan Seelecke
Keyword(s):  
Boundary Conditions ◽  
Temperature Phase ◽  
Thermomechanical Model ◽  
Finite Element Program ◽  
Temperature Boundary ◽  
Element Program ◽  
Sma Actuator ◽  
Effects Of Temperature ◽  
The Wire ◽  
Stiff Spring

The effects of temperature boundary conditions and the resulting performance of an SMA actuator were studied for an SMA wire coupled with a stiff spring. The wire was actuated via joule heating under both adiabatic and isothermal boundary conditions. The resulting temperature, phase fraction, strain and stress profiles along the wire were studied together with the wire tip displacement. The simulations were conducted using the finite element program ABAQUS, and a fully thermo-mechanically coupled shape memory alloy (SMA) actuator model was used to simulate the behavior. ABAQUS’s user material (UMAT) feature was utilized to model the SMA wire using a mesoscopic free energy model [1] in order to accurately describe the thermomechanically coupled actuator behavior. The results from the simulations highlighted the differences between homogeneous and inhomogeneous profiles, and a 34% difference in actuation stroke between the two cases was observed.

scholarly journals Monte Carlo Simulations of Coupled Transient Seepage Flow and Soil Deformation in Levees

2020 ◽  
Vol 21 (1) ◽  
pp. 147-156
Author(s):  
Fred Thomas Tracy ◽  
Jodi L. Ryder ◽  
Martin T. Schultz ◽  
Ghada S. Ellithy ◽  
Benjamin R. Breland ◽  
...  
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
Boundary Conditions ◽  
High Performance ◽  
Hurricane Ike ◽  
Finite Element Program ◽  
Conservation Of Mass ◽  
Total Head ◽  
Element Program ◽  
Finite Element Node

The purpose of this research is to compare the results from two different computer programs of flow analysesof two levees at Port Arthur, Texas where rising water of a flood from Hurricane Ike occurred on the levees. The first program (Program 1) is a two-dimensional (2-D) transient finite element program that couples the conservation of mass flow equation with accompanying hydraulic boundary conditions with the conservation of force equations with accompanying x and y displacement and force boundary conditions, thus yielding total head, x displacement, and y displacement as unknowns at each finite element node. The second program (Program 2) is a 2-D transient finite element program that considers only the conservation of mass flowequation with its accompanying hydraulic boundary conditions, yielding only total head as the unknown at each finite element node. Compressive stresses can be computed at the centroid of each finite element when using the coupled program. Programs 1 and 2 were parallelized for high performance computing to consider thousands of realisations of the material properties. Since a single realisation requires as much as one hour of computer time for certain levees, the large realisation computation is made possible by utilising HPC. This Monte Carlo type analysis was used to compute the probability of unsatisfactory performance for under seepage, through seepage, and uplift for the two levees. Respective hydrographs from the flood resulting from Hurricane Ike were applied to each levee. When comparing the computations from the two programs, the most significant result was the two programs yielded significantly different values in the computed results in the two clay levees considered in this research.  

Predicting the Impact of Quenching on Mechanical Properties of Complex-Shaped Aluminum Alloy Parts

1995 ◽  
Vol 117 (2) ◽  
pp. 479-488 ◽  
Author(s):  
D. D. Hall ◽  
I. Mudawar
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Boundary Conditions ◽  
Finite Element Program ◽  
Part Geometry ◽  
Heat Treated ◽  
Element Program ◽  
Nozzle Configuration ◽  
The Impact

The mechanical properties of age-hardenable aluminum alloy extrusions are critically dependent on the rate at which the part is cooled (quenched) after the forming operation. The present study continues the development of an intelligent spray quenching system, which selects the optimal nozzle configuration based on part geometry and composition such that the magnitude and uniformity of hardness (or yield strength) is maximized while residual stresses are minimized. The quenching of a complex-shaped part with multiple, overlapping sprays was successfully modeled using spray heat transfer correlations as boundary conditions within a finite element program. The hardness distribution of the heat-treated part was accurately predicted using the quench factor technique; that is, the metallurgical transformations that occur within the part were linked to the cooling history predicted by the finite element program. This study represents the first successful attempt at systematically predicting the mechanical properties of a quenched metallic part from knowledge of only the spray boundary conditions.

Thermomechanical Modeling of a Wet Shape Memory Alloy Actuator

2006 ◽  
Author(s):  
Joel Ertel ◽  
Stephen Mascaro
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Temperature Change ◽  
Cold Water ◽  
Uniform Temperature ◽  
Thermomechanical Model ◽  
Martensite Fraction ◽  
Mechanical Models ◽  
Sma Actuator ◽  
The Wire

This paper presents combined thermal and mechanical models of a wet shape memory alloy (SMA) wire actuator. The actuator consists of a SMA wire suspended concentrically in a compliant tube. Actuation occurs as hot and cold water are alternately pumped through the tube to contract and extend the wire, respectively. Although other constitutive models of the behavior of SMA's exist, they generally assume uniform temperature change throughout the SMA actuator. The thermomechanical model presented in this paper accounts for the non-uniform temperature change of the SMA wire due to alternating the temperature of the flow along the wire. The thermal model consists of analysis of the heat transfer between the fluid and the SMA wire. Heat loss to the environment and the temperature change of the fluid through the actuator are taken into account. Based on this analysis the temperature of the wire at segments along its length can be determined as a function of time. The mechanical model approximates the strain-martensite fraction and martensite fraction-temperature relationships. By combining the thermal and mechanical models the strain of the wire can be determined as a function of time. The combined thermomechanical model will be used to model applications in which a wet SMA actuator is desired.

Section Translational Movement Imposition for Macroelements

2019 ◽  
Author(s):  
Rodrigo Provasi ◽  
Clóvis de Arruda Martins
Keyword(s):  
Boundary Conditions ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Cylindrical Layer ◽  
Finite Element Program ◽  
Translational Movement ◽  
Specific Contact ◽  
Element Program ◽  
Contact Models ◽  
Constraint Enforcement

Abstract Boundary conditions play a very important role in any mathematical model. They heavily influence the response near the region they are, but the farther the interest region is, the less important the boundary condition influence becomes. Also, the response depends of which movements are constrained or imposed and which are not. This influence can be seen in all type of problems, ranging from simple beams to complicated structures. For tubular structures, such as flexible pipes and umbilical cables, the boundary conditions are usually given in terms of imposed movements in sections, which are commonly assumed, by hypothesis, as rigid bodies. To deal with this type of structures, the authors presented in previous works the macroelements. They are finite elements that incorporate geometrical characteristics in the formulation, leading to well behaved contact models with a smaller number of degrees of freedom. One major feature of the model is the orthotropic cylindrical layer that uses Fourier series for the displacements. This led to specific contact models and bring the difficulty in the representation of boundary conditions in terminal sections, since different nature displacements (one the aforementioned Fourier and other one standard description) must be dealt with. This paper address how to impose translational movement for sections using macroelements. All the description of how the coupling is made and the constraint enforcement done by using a penalty-based formulation. This work also highlights the implementation, finalizing with comparison with a conventional finite element program.

scholarly journals Use of the Finite Element Method in Predicting Vibrations of Sandwich Beams and Plates Resting on Deformable Foundations Subjected to Moving Loads

2017 ◽  
Vol 63 (4) ◽  
pp. 51-69
Author(s):  
A. Zbiciak ◽  
M. Ataman ◽  
W. Szcześniak
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Core Layer ◽  
Sandwich Beams ◽  
Moving Loads ◽  
The Finite Element Method ◽  
Finite Element Program ◽  
Element Program ◽  
Foundation Parameters

AbstractThis paper presents the capabilities of ABAQUS finite-element program [1] in modelling sandwich beams and plates resting on deformable foundations. Specific systems of sandwich beams and plates separated by an elastic core layer were subjected to the action of point and distributed moving loads. A few theoretical examples are provided to present different techniques of modelling the foundations and the moving loads. The effects of the boundary conditions and of the foundation parameters on the deflections of the analysed structures are also presented.

Determination of Temperatures and Heat Fluxes on Surfaces and Interfaces of Multi-Domain Three-Dimensional Electronic Components

2003 ◽  
Author(s):  
Brian H. Dennis ◽  
Zhen-Xue Han ◽  
George S. Dulikravich
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Measurement Errors ◽  
Sparse Matrix ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Junction Temperature ◽  
Element Formulation ◽  
Finite Element Program ◽  
Element Program

A finite element method (FEM) formulation for the prediction of unknown steady boundary conditions in heat conduction for multi-domain three-dimensional solid objects is presented. The FEM formulation is capable of determining temperatures and heat fluxes on the boundaries where such quantities are unknown, provided such quantities are sufficiently over-specified on other boundaries. An inverse finite element program has been previously developed and successfully tested on 3-D simple geometries. The finite element code uses an efficient sparse matrix storage scheme that allows treatment of realistic three-dimensional problems on personal computer. The finite element formulation also allows for very straight-forward treatment of geometries composed of many different materials. The inverse FEM formulation was applied to the prediction of die junction temperature distribution in a simple ball grid array (BGA) electronic package. Examples are presented with simulated measurement that include random measurement errors. Regularization was applied to control numerical error when large measurement errors were added to the over-specified boundary conditions.

Determination of Temperatures and Heat Fluxes on Surfaces and Interfaces of Multidomain Three-Dimensional Electronic Components

2004 ◽  
Vol 126 (4) ◽  
pp. 457-464 ◽  
Author(s):  
Brian H. Dennis ◽  
Zhen-xue Han ◽  
George S. Dulikravich
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Measurement Errors ◽  
Sparse Matrix ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Junction Temperature ◽  
Element Formulation ◽  
Finite Element Program ◽  
Element Program

A finite element method (FEM) formulation for the prediction of unknown steady boundary conditions in heat conduction for multidomain three-dimensional (3D) solid objects is presented. The FEM formulation is capable of determining temperatures and heat fluxes on the boundaries where such quantities are unknown, provided such quantities are sufficiently overspecified on other boundaries. An inverse finite element program has been previously developed and successfully tested on 3D simple geometries. The finite element code uses an efficient sparse matrix storage scheme that allows treatment of realistic 3D problems on personal computer. The finite element formulation also allows for very straightforward treatment of geometries composed of many different materials. The inverse FEM formulation was applied to the prediction of die-junction temperature distribution in a simple ball grid array electronic package. Examples are presented with simulated measurements, which include random measurement errors. Regularization was applied to control numerical error when large measurement errors were added to the overspecified boundary conditions.

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