Enhanced Design of Microgripper Using Double Actuators of Shape Memory Alloy Wires

2014 ◽  
Author(s):  
Qais Khasawneh ◽  
Mohammad A. Jaradat ◽  
Ahmad Alshorman
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Software Package ◽  
Element Model ◽  
Ansys Software ◽  
Micro Gripper ◽  
Sma Actuator ◽  
Main Material

In this paper, new design of micro-gripper with shape memory alloy (SMA) actuator is presented. Double SMA actuators were used to enhance the performance of the micro-gripper by using hinge mechanisms; the little displacement of the SMA wire is converted into larger displacement of the tips of the micro-gripper. Stainless steel (St 304) was used as a main material of the gripper structure. Shape memory alloy (Ni-Ti) wires were used as actuators. Finite element model analysis (FEA) using ANSYS software package was used to simulate displacement and stress analysis on the micro gripper. Finally a comparison between the enhanced design and the initial one showed better results in terms of increasing the gripper stroke and reducing the stress on the gripper joints.

scholarly journals MODERN APPROACHES TO SOLVING THE CONTACT PROBLEM OF PRESSING A DOUBLESTAMP STAMP INTO AN ELASTIC HALF-SPACE

2021 ◽  
pp. 74-79
Author(s):  
Tetyana Zaytseva ◽  
Ivan Shmelov
Keyword(s):  
Finite Element ◽  
Half Space ◽  
Contact Area ◽  
Software Package ◽  
Complex Shape ◽  
Element Model ◽  
Circular Ring ◽  
Elastic Half Space ◽  
Ansys Software ◽  
Java Language

The work is devoted to solving indentation problems into an elastic half-space of a cylindrical punch with a flat base by the vertical force. The force is aimed through the center of the base. The cross-section of the stamp is a doubly connected area bounded by two concentric lines. A concise review of methods for solving problems of analyzing the contact interaction of cylindrical dies with an elastic half-space is given. The solution of the problem in the form of decomposition by a small parameter is used when the equation of the edge curves depends on the same small parameter. To achieve it, in each approximation, the problem of indentation of a stamp with a doubly connected contact area in the form of a non-circular ring is reduced to a similar problem of indentation of a stamp with a contact area in the form of a circular ring. The software in the Java language has been developed for processing the analytical solution according to the obtained calculation formulas. With the help of the ANSYS software package, a finite element model of the contact interaction of an absolutely rigid stamp with an elastic half-space has been created. Numerical modeling was carried out using a licensed version of the program, free of charge. Several problems have been solved for square rings of different widths. The distribution of pressure under the stamp over different sections and the deepening of the stamp have been obtained. The pressure distribution graphs are plotted. When considering several test problems to assess the adequacy of the finite element model, the numerical results are compared with the results obtained analytically. The resulting model can analyze and predict loads, wear, and fracture of the contact area. The research prospects can include the solution of several problems of analysis of the stress-strain state of the interaction of dies of a complex shape with an elastic half-space, as well as groups of stamps of a complex shape, and the analysis of behavior models depending on the properties and characteristics of an elastic half-space. Keywords: contact problem, stamp, stress-strain state, modeling, JAVA language, finite element analysis, ANSYS software package.

Thermomechanical Modelling and Experimental Testing of a Shape Memory Alloy Hybrid Composite Plate

2008 ◽  
Vol 59 ◽  
pp. 41-46 ◽  
Author(s):  
Federica Daghia ◽  
Gabriella Faiella ◽  
Vincenza Antonucci ◽  
Michele Giordano
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Finite Element Model ◽  
Shape Memory ◽  
Functional Properties ◽  
Hybrid Composite ◽  
Experimental Testing ◽  
Element Model ◽  
Electrical Heating ◽  
Simultaneous Generation

Shape memory alloys (SMA) exhibit functional properties associated with the shape memory effect, responsible of the SMA shape recovery after a cycle of deforming-heating and of a simultaneous generation of mechanical work. Composite systems incorporating SMA wires have the ability to actively change shape and other structural characteristics. The functional properties of such adaptive composites are related to the martensitic transformation in the SMA elements and to the constraining behaviour that the composite matrix has on the SMA wires. In this work the behaviour of a shape memory alloy hybrid composite (SMAHC) is numerically and experimentally investigated. A plate was fabricated using prestrained SMA wires embedded in an epoxy resin pre preg glass fibres composite system. Upon calorimetric and mechanical material characterization, a finite element model was used in order to predict the structural behaviour of the SMAHC. In the experimental tests, the plate was clamped at one side and actuated via electrical heating. Temperature and displacement data were collected and compared with the prediction of the finite element model. The results show that the model is able to capture the shape change in the actuation region, although a thorough description of the SMAHC behaviour requires further modelling work, including the simulation of the SMA loading history during composite manufacturing.

Modeling of Artificial Aurelia aurita Bell Deformation

2011 ◽  
Vol 45 (4) ◽  
pp. 165-180 ◽  
Author(s):  
Keyur B. Joshi ◽  
Alex Villanueva ◽  
Colin F. Smith ◽  
Shashank Priya
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Transient Behavior ◽  
Element Model ◽  
Aurelia Aurita ◽  
Thermal Coefficient ◽  
Power Cycle ◽  
Element Simulation ◽  
The Difference

AbstractRecently, there has been significant interest in developing underwater vehicles inspired by jellyfish. One of these notable efforts includes the artificial Aurelia aurita (Robojelly). The artificial A. aurita is able to swim with similar proficiency to the A. aurita species of jellyfish even though its deformation profile does not completely match the natural animal. In order to overcome this problem, we provide a systematic finite element model (FEM) to simulate the transient behavior of the artificial A. aurita vehicle utilizing bio-inspired shape memory alloy composite (BISMAC) actuators. The finite element simulation model accurately captures the hyperelastic behavior of EcoFlex (Shore hardness-0010) room temperature vulcanizing silicone by invoking a three-parameter Mooney-Rivlin model. Furthermore, the FEM incorporates experimental temperature transformation curves of shape memory alloy wires by introducing negative thermal coefficient of expansion and considers the effect of gravity and fluid buoyancy forces to accurately predict the transient deformation of the vehicle. The actual power cycle used to drive artificial A. aurita vehicle was used in the model. The overall profile error between FEM and the vehicle profile is mainly due to the difference in initial relaxed profiles.

Nonlinear two-dimensional finite element model for transient and damping analysis of cylindrical sandwich panels with pseudoelastic shape memory alloy composite face sheets

2017 ◽  
Vol 21 (1) ◽  
pp. 19-76 ◽  
Author(s):  
Maryam Khanjani ◽  
Mahmoud Shakeri ◽  
Mojtaba Sadighi
Keyword(s):  
Finite Element ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Volume Fraction ◽  
Element Model ◽  
Martensite Phase ◽  
Governing Equations ◽  
Time Step ◽  
Composite Face

A new nonlinear finite element model is proposed for the dynamic analysis of cylindrical sandwich panels with shape memory alloy hybrid composite face sheets and flexible core. In order to present a realistic transient vibration analysis, all the material complexities arising from the instantaneous and spatial martensite phase transformation of the shape memory alloy wires are taken into consideration. The one-dimensional constitutive equation proposed by Boyd and Lagoudas is used for modeling the pseudoelastic behavior of the shape memory alloy wires. Since the martensite volume fraction at each point depends on the stress at that point, the phase transformation kinetic equations and the governing equations are coupled together. Therefore, at each time step, an iterative method should be used to solve the highly nonlinear equations. Moreover, considering that the stress resultants generated by the martensite phase transformation in the wires are path-dependent values, an incremental method is used to estimate the increment of the stress resultants at each time step. The governing equations are derived based on the energy method and Newmark time integration method is used to solve the discretized finite element equations. Finally, several numerical examples are presented to examine the effect of various parameters such as intensity of applied pressure load, operating temperature, location of shape memory alloy wires, volume fraction of the shape memory alloy wires, and also boundary conditions upon the loss factor for panels with different aspect ratios.

scholarly journals Study on Interference Connection Based on Shape Recovery of NiTiNb Shape Memory Alloy

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2328
Author(s):  
Haojie Niu ◽  
Yubin Sun ◽  
Chengxin Lin ◽  
Yutang Zou
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Element Model ◽  
Interference Fit ◽  
Pull Out ◽  
Hole Wall ◽  
Element Simulation ◽  
Change Trend

Interference connection is an effective method for improving the fatigue life of bolt connections. In this paper, a new method of interference connection was designed based on the shape memory effect of shape memory alloy. Using the method of numerical simulation, a finite element model was established to analyze the stress–strain rule of the bolt and the hole wall under different interference fit sizes. The results show that the stress concentration is formed at the orifice of the connecting plate. When the interference fit size is less than 1%, the connection hole has elastic deformation. When the interference fit size is 1.5%, the hole wall has plastic deformation. When the interference fit size is 2.5%, the maximum stress on the connecting plate is close to the tensile limit of the material. If the interference fit size continues to increase, the strength of the connection structure will be damaged. The connection experiments with different interference fit size were designed, and the interference force was calculated by the pull-out force. The experimental results were compared with the numerical simulation results. The change trend of the interference force with the interference fit size is consistent, which verifies the rationality of the finite element simulation.

Experimental Characterization and Modelling Validation of Shape Memory Alloy Negator Springs

2013 ◽  
Author(s):  
Andrea Spaggiari ◽  
Eugenio Dragoni ◽  
Ausonio Tuissi
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Analytical Model ◽  
Element Model ◽  
Design Tool ◽  
Experimental Characterization ◽  
Finite Element Software ◽  
Spiral Spring ◽  
Force Displacement

This paper is aimed at the experimental characterization and modelling validation of shape memory alloy (SMA) negator springs. A Negator spring is a spiral spring made of strip of metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbour. The main feature of a Negator springs is the nearly-constant force displacement behaviour in the unwinding of the strip. Moreover the stroke is very long, theoretically infinite as it depends only on the length of the initial strip. A Negator spring made in SMA is built and experimentally tested to demonstrate the feasibility of this actuator. The shape memory Negator spring behaviour is predicted both with an analytical model and with a a finite element software. In both cases the material is modelled as elastic in austenitic range while an exponential continuum law is used to describe the martensitic behaviour. The experimental results confirms the applicability of this kind of geometry to the shape memory alloy actuators and the analytical model is confirmed to be a powerful design tool to dimension and predict the spring behaviour both in martensitic and austenitic range, as well as the finite element model developed.

Finite Element Analysis of Creep and Thermal Stress for Shape Memory Alloy Joint

2010 ◽  
Vol 452-453 ◽  
pp. 537-540 ◽  
Author(s):  
Xue Feng Zhou ◽  
You Hai Zhi ◽  
Bing Wang Gou
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Strain ◽  
Three Dimensional ◽  
Transient State ◽  
Element Model ◽  
Element Analysis ◽  
Joint System ◽  
Radial Temperature

The three-dimensional (3D) finite element model of shape memory alloy (SMA) joint system under a clamped-clamped support was established. Using the coupled thermal-mechanical transient state analysis, stress distributions of models under the different loads (internal pressure, temperature) were investigated. And the temperature field, thermal strain field, stress and creep of the joint system were obtained. The results show, 1) for the non-coat SMA joint system, the interface in middle region of the joint’s internal wall is the dangerous region. In this region, the joint’s adhesion failures easily occur and the crack easily initiate. The joint’s coat can improve the fatigue life of joint system. 2) There are higher levels of radial temperature gradient, temperature strain and temperature stress between the internal and external walls of the joint. The creep strain in the internal-external walls of the joint is the main reason for adhesion failure in middle interfaces between the joint and the pipe.

A finite element framework for a shape memory alloy actuated finger

2019 ◽  
Vol 30 (14) ◽  
pp. 2052-2064 ◽  
Author(s):  
Filomena Simone ◽  
Gianluca Rizzello ◽  
Stefan Seelecke
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Element Model ◽  
High Energy ◽  
Good Choice ◽  
Material Behavior ◽  
Hysteretic Behavior ◽  
High Energy Density ◽  
Alloy Material

This article presents on finite element modeling of an artificial finger driven by shape memory alloy wires. These alloys appear as a promising transduction technology, due to their inherently high energy density which makes them a good choice for compact, lightweight, and silent actuator systems with many applications in the robotic field, ranging from industrial to biomedical ones. However, the complex nonlinear and hysteretic behavior of the material makes it difficult to accurately model and design shape memory alloy–actuated systems. The problem is even more challenging when shape memory alloys are used as actuators in articulated structures, adding complex kinematics and contact situations to the picture. In this article, a finite element model is developed to describe the behavior of a finger prototype, in which a bundle of shape memory alloy wires works against an extension spring. The commercially available software COMSOL is used for implementing the coupling and contact issues between the finger structure and the shape memory alloy wires. To describe the shape memory alloy material behavior, a COMSOL implementation of the Müller–Achenbach–Seelecke model is presented. By means of different experiments, it is demonstrated how the model predicts the prototype behavior in relation to different power stimuli and actuator geometries.

Shape memory alloy sensory particles for damage detection: Experiments, analysis, and design studies

2017 ◽  
Vol 17 (4) ◽  
pp. 777-814 ◽  
Author(s):  
Brent R Bielefeldt ◽  
Jacob D Hochhalter ◽  
Darren J Hartl
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Structural Damage ◽  
Structural Integrity ◽  
Fatigue Cracks ◽  
Element Model ◽  
Optimization Method ◽  
Sensory Response ◽  
Analysis And Design

Developing novel techniques for monitoring structural integrity has become an important area of research in the aerospace community. One new technique exploits the stress-induced phase transformation behavior in shape memory alloy particles embedded in a structure. By monitoring changes in the mechanical and/or electromagnetic behavior of such particles, the formation or propagation of fatigue cracks in the vicinity of these particles can be detected. This work demonstrates sensory particle response to local structural damage using finite element modeling for the first time. Using an optimization method to minimize the difference between experimentally measured strain and simulated results, a good approximation of sensory particle properties can be determined and the strong sensory response of the transforming particle demonstrated. To illustrate an application of this method, a multi-scale finite element model of sensory particles embedded in the root rib of an aircraft wing is then considered. In particular, this unique model utilizes substructure modeling to maintain computational efficiency while relating globally applied loads to local structural response, allowing for the consideration of predicted particle response to crack propagation during wing loading. The effect of particle position relative to the crack tip on particle sensory response is assessed. Finally, this work demonstrates how sensory particles can be used to approximate the location of structural damage by interpolating a stress field based on the responses of multiple sensory particles in the vicinity of a propagating crack.

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