scholarly journals Finite-element modelling of NiTi shape-memory wires for morphing aerofoils

2020 ◽  
Vol 124 (1281) ◽  
pp. 1740-1760
Author(s):  
W.L.H. Wan A. Hamid ◽  
L. Iannucci ◽  
P. Robinson
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Cantilever Beam ◽  
Material Model ◽  
Sensitivity Study ◽  
Niti Shape Memory Alloy ◽  
Element Analysis ◽  
Cross Sectional ◽  
Explicit Finite Element ◽  
Thermomechanical Behaviour

AbstractThis paper presents the development and implementation of a user-defined material (UMAT) model for NiTi Shape-Memory Alloy (SMA) wires for use in LS-DYNA commercial explicit finite-element analysis software. The UMAT focusses on the Shape-Memory Effect (SME), which could be used for actuation of aerostructural components. The actuation of a fundamental structure consisting of an SMA wire connected in series with a linear spring was studied first. The SMA thermomechanical behaviour obtained from the finite-element simulation was compared with that obtained from the analytical solution in MATLAB. A further comparison is presented for an SMA-actuated cantilever beam, showing excellent agreement in terms of the SMA stress and strain as well as the tip deflection of the cantilever beam. A mesh sensitivity study on the SMA wire indicated that one beam element was adequate to accurately predict the SMA thermomechanical behaviour. An analysis of several key parameters showed that, to achieve a high recovery strain, the stiffness of the actuated structure should be minimised while the cross-sectional area of the SMA wire should be maximised. The actuation of an SMA wire under a constant stress/load was also analysed. The SMA material model was finally applied to the design of morphing aluminium and composite aerofoils consisting of corrugated sections, resulting in the prediction of reasonably large trailing-edge deflections (7.8–65.9 mm).

Finite Element Modeling of Non-Orthogonal Loosely Woven Fabrics in Advanced Occupant Restraint Systems

2001 ◽  
Author(s):  
Romil R. Tanov ◽  
Marlin Brueggert
Keyword(s):  
Finite Element ◽  
Material Model ◽  
General Purpose ◽  
Woven Fabrics ◽  
Element Analysis ◽  
Correct Operation ◽  
Explicit Finite Element ◽  
Analysis Scheme ◽  
Occupant Restraint Systems ◽  
Protection Devices

Abstract The behavior of loosely woven fabrics differs significantly from other types of woven fabrics. Its unique characteristics have been successfully utilized for the correct operation of some recently developed occupant protection devices for the automotive and heavy machine and truck industry. However, this behavior cannot be efficiently modeled using the currently available material models within a finite element analysis scheme. Therefore, the aim of this work is to present the basics of a formulation of a material model for the analysis of loosely woven fabrics and its implementation in a general-purpose explicit finite element code. To assess the performance of the model, results from the simulation are presented and compared to real test data.

The effects of shape memory alloys’ tension–compression asymmetryon NiTi endodontic files’ fatigue life

2018 ◽  
Vol 232 (5) ◽  
pp. 437-445 ◽  
Author(s):  
MR Karamooz-Ravari ◽  
R Dehghani
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Element Model ◽  
Niti Shape Memory Alloy ◽  
Element Analysis ◽  
Tension And Compression ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Nowadays, NiTi rotary endodontic files are of great importance due to their flexibility which enables the device to cover all the portions of curved canal of tooth. Although this class of files are flexible, intracanal separation might happen during canal preparation due to bending or torsional loadings of the file. Since fabrication and characterization of such devices is challenging, time-consuming, and expensive, it is preferable to predict this failure before fabrication using numerical models. It is demonstrated that NiTi shape memory alloy shows asymmetric material response in tension and compression which can significantly affect the lifetime of the files fabricated from. In this article, the effects of this material asymmetry on the bending response of rotary files are assessed using finite element analysis. To do so, a constitutive model which takes material asymmetry into account is used in combination with the finite element model of a RaCe file. The results show that the material asymmetry can significantly affect the maximum von Mises equivalent stress as well as the force–displacement response of the tip of this file.

scholarly journals Finite Element Analysis of RC Beams by the Discrete Model and CBIS Model Using LS-DYNA

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Seung H. Yang ◽  
Kwang S. Woo ◽  
Jeong J. Kim ◽  
Jae S. Ahn
Keyword(s):  
Finite Element ◽  
Discrete Model ◽  
Kinematic Hardening ◽  
Material Model ◽  
General Purpose ◽  
Solid Model ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Finite Element Software ◽  
Concrete Elements

There are several techniques to simulate rebar reinforced concrete, such as smeared model, discrete model, embedded model, CLIS (constrained Lagrange in solid) model, and CBIS (constrained beam in solid) model. In this study, however, the interaction between the concrete elements and the reinforcement beam elements is only simulated by the discrete model and CBIS (constrained beam in solid) model. The efficiency and accuracy comparisons are investigated with reference to the analysis results by both models provided by LS-DYNA explicit finite element software. The geometric models are created using LS-PrePost, general purpose preprocessing software for meshing. The meshed models are imported to LS-DYNA where the input files are then analyzed. Winfrith and CSCM concrete material options are employed to describe the concrete damage behavior. The reinforcement material model is capable of isotropic and kinematic hardening plasticity. The load versus midspan deflection curves of the finite element models correlate with those of the experiment. Under the conditions of the same level of accuracy, the CBIS model is evaluated to have the following advantages over the discrete model. First, it has the advantage of reducing the time required for FE modeling; second, saving computer CPU time due to a reduction in total number of nodes; and third, securing a good aspect ratio of concrete elements.

A Bodner Type of Material Model for the Description of Foam Properties

2001 ◽  
Author(s):  
Yuzhao Song ◽  
Ziqi Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Automobile Industry ◽  
Material Model ◽  
Finite Element Code ◽  
Foam Material ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Compression Strain ◽  
Foam Properties

Abstract A unified constitutive equation has been used to represent Foam material. It can describe the large compression strain, compression strain rate, tension strain and the bottom out behavior of various foams. The material has been incorporated into LS-DYNA, an explicit finite element code widely used in the automobile industry. An example is given to show an application of the material model in a low speed impact finite element analysis.

Finite Element Analysis of Precipitation Effects on Ni-Rich NiTi Shape Memory Alloy Response

2014 ◽  
Vol 792 ◽  
pp. 65-71 ◽  
Author(s):  
Austin Cox ◽  
Theocharis Baxevanis ◽  
Dimitris C. Lagoudas
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Thermomechanical Properties ◽  
Precipitation Process ◽  
Niti Shape Memory Alloy ◽  
The Finite Element Method ◽  
Material Microstructure ◽  
Element Analysis ◽  
The Matrix ◽  
Niti Shape Memory Alloys

Thermomechanical properties of precipitated NiTi shape memory alloys are investigated using the finite element method. The precipitated material microstructure is explored using a representative volume element with embedded Ni4Ti3 precipitates. Features such as precipitate coherency and distribution of Ni within the matrix due to the precipitation process are individually explored and characterized. Changes in the material’s macroscopic thermomechanical response due to this precipitation are determined.

Improving failure sub-models in an orthotropic plasticity-based material model

2020 ◽  
pp. 002199832098265
Author(s):  
Loukham Shyamsunder ◽  
Bilal Khaled ◽  
Subramaniam D Rajan ◽  
Gunther Blankenhorn
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
High Speed ◽  
Simulation Models ◽  
Material Model ◽  
Failure Criteria ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
Static Tensile

Theoretical details of two failure criteria implemented in an orthotropic plasticity model are presented. Improvements to the well-known Puck Failure criterion and a recently developed Generalized Tabulated Failure criterion are used to illustrate how to link a failure sub-model to existing deformation and damage sub-models in the context of explicit finite element analysis. These models are implemented in LS-DYNA, a commercial transient dynamic finite element code. Two validation tests are used to evaluate the failure sub-model implementation and improvements - a stacked-ply test carried out at room temperature under quasi-static tensile and compressive loadings, and a high-speed, projectile impact test where there is significant damage and material failure of the impacted panel. Results indicate that developed procedures and improvements provide the analyst with a reasonable and systematic approach to building predictive impact simulation models.

Experimental and numerical investigation of cutting forces during turning of cylindrical AISI 4340 steel specimens

2021 ◽  
Vol 63 (5) ◽  
pp. 402-410
Author(s):  
Oğur İynen ◽  
Abdul Kadir Ekşi ◽  
Mustafa Özdemir ◽  
Hamza Kemal Akyıldız
Keyword(s):  
Finite Element ◽  
Cutting Forces ◽  
Material Model ◽  
Numerical Results ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
The Finite Element Analysis ◽  
Hardness Scale ◽  
Coated Carbide ◽  
Aisi 4340

Abstract Cutting forces play a significant role in machining because they directly affect the mechanics of machining, the energy requirements, and the tool stability required. In this study, the cutting forces occurring during the turning of AISI 4340 material with 30 Rockwell C hardness scale have been analyzed both experimentally and numerically. Many types of research have been conducted via 2-D simulation using the finite element analysis method. In other words, in most studies, the workpiece was modeled as a flat specimen. Therefore, this paper presents a real 3-D turning simulation model using cylindrical specimens. The cutting forces were measured using a Kistler 9129AA model piezoelectric dynamometer. The ABAQUS/Explicit finite element method was used, and a model by Johnson and Cook was assigned as a material model in the numerical analysis. A new PVD AlTiN coated carbide insert was incorporated to prevent wear. Experimental results obtained from cutting tests were compared with numerical results to establish the accuracy of the FEM. It was observed that experimental and numerical results overlapped each other. Thus, this method can be used directly in the industry to reduce high processing costs.

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