scholarly journals Experimental and Numerical Analysis of Recovery Stress in Ni47Ti44Nb9 Shape Memory Alloys: Application to Tightening

2010 ◽  
Author(s):  
Boris Piotrowski ◽  
Etienne Patoor ◽  
Tarak Ben-Zineb ◽  
Andre Eberhardt
Keyword(s):  
Finite Element ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Experimental Tests ◽  
Constitutive Law ◽  
Recovery Stress ◽  
Test Bed ◽  
Home Test ◽  
Niti Sma ◽  
Transformation Hysteresis

Ni47Ti44Nb9 Shape Memory Alloys (SMAs) are widely considered for tightening applications. The alloy is composed of a NiTi SMA matrix containing niobium precipitates. A specific thermomechanical treatment strongly increases the transformation hysteresis in these alloys, what improves the tightening efficiency. Tightening pressures exhibited by Ni47Ti44Nb9 rings are experimentally investigated. Strain gage measurements allow to monitor the tightening pressure using a home test bed. Evolutions with temperature are recorded. A thermo-mechanical constitutive law, specific for Ni47Ti44Nb9, is proposed. It is based on the Mori-Tanaka scale transition technique by considering the precipitates as elastic-plastic inclusions embedded in the SMA matrix. The resulting effective law is implemented, and validated in ABAQUS via UMAT subroutine. Experimental tests are simulated by Finite Element Modeling, and comparisons are performed.

A Finite Element Study of Stable Crack-Growth in Superelastic Shape Memory Alloys

2012 ◽  
Author(s):  
Antonino Parrinello ◽  
Theocharis Baxevanis ◽  
Dimitris Lagoudas ◽  
Austin Cox
Keyword(s):  
Finite Element ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Crack Growth ◽  
Small Strain ◽  
Stable Crack Growth ◽  
Constitutive Law ◽  
Scale Transformation ◽  
Small Scale ◽  
Element Analysis

A finite-element analysis of stable crack growth in superelastic Shape Memory Alloys (SMAs) is carried out for plane strain, mode I loading. The small-scale transformation assumption is employed in the calculations using displacement boundary conditions on a circular region that encloses the stress-induced phase transformation zone. The constitutive law adopts the classical rate-independent small-strain flow theory for the evolution equation of the transformation strains. The crack is assumed to propagate quasi-statically with the energy release rate maintained at a critical value; the analysis is accomplished by means of the Virtual Crack Closure Technique (VCCT). Resistance curves, obtained for a range of thermomechanical parameters, show enhanced fracture toughness.

Smart polyimide with recovery stress at the level of high temperature shape memory alloys

2021 ◽  
Vol 30 (3) ◽  
pp. 035027
Author(s):  
Deyan Kong ◽  
Jie Li ◽  
Anru Guo ◽  
Jianxin Yu ◽  
Xinli Xiao
Keyword(s):  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Recovery Stress

scholarly journals The Instability Improvement of the Symmetric Angle-Ply and Cross-Ply Composite Plates with Shape Memory Alloy Using Finite Element Method

2014 ◽  
Vol 6 ◽  
pp. 632825 ◽  
Author(s):  
Zainudin A. Rasid ◽  
Rizal Zahari ◽  
Amran Ayob
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Volume Fraction ◽  
Shear Deformation Theory ◽  
Composite Plates ◽  
Element Formulation ◽  
Recovery Stress ◽  
Buckling Behavior ◽  
Post Buckling

Shape memory alloy (SMA) wires were embedded within laminated composite plates to take advantage of the shape memory effect property of the SMA in improving post-buckling behavior of composite plates. A nonlinear finite element formulation was developed for this study. The plate-bending formulation used in this study was developed based on the first order shear deformation theory, where the von Karman's nonlinear moderate strain terms were added to the strain equations. The effect of the SMA was captured by adding recovery stress term in the constitutive equation of the SMA composite plates. Values of the recovery stress of the SMA were determined using Brinson's model. Using the principle of virtual work and the total Lagrangian approach, the final finite element nonlinear governing equation for the post-buckling of SMA composite plates was derived. Buckling and post-buckling analyses were then conducted on the symmetric angle-ply and cross-ply SMA composite plates. The effect of several parameters such as the activation temperature, volume fraction, and the initial strain of the SMA on the post-buckling behavior of the SMA composite plates were studied. It was found that significant improvements in the post-buckling behavior for composite plates can be attained.

Deployable Process Analysis of Packaged SMP Sandwich Beam

2010 ◽  
Vol 123-125 ◽  
pp. 943-946 ◽  
Author(s):  
Zheng Fa Li ◽  
Zheng Dao Wang
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Sandwich Structure ◽  
Shape Recovery ◽  
Process Analysis ◽  
Sandwich Beam ◽  
Shape Memory Polymers ◽  
Recovery Stress ◽  
Recovery Response

Shape memory polymers own many advantages compared with traditional shape memory alloys or ceramics. In order to improve their shape recovery stress and realize a stable recovery response during the deployable process, the structure of SMP sandwich beam composed of two metallic skin and one SMP core is considered. The recovery behaviors of pure SMP and SMP beams reinforced by one-layer metallic skin are also discussed for comparison. The results confirm that the deployable properties of SMP matrix can be significantly improved by using sandwich structure.

Corrugated structures reinforced by shape memory alloy sheets: Analytical modeling and finite element modeling

2018 ◽  
Vol 233 (7) ◽  
pp. 2445-2454 ◽  
Author(s):  
Maryam Koudzari ◽  
Mohammad-Reza Zakerzadeh ◽  
Mostafa Baghani
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Finite Element Modeling ◽  
Shape Memory ◽  
Smart Structure ◽  
Design Parameters ◽  
Asymmetric Mode ◽  
Element Modeling ◽  
Structure Changes

In this study, an analytical solution is presented for a trapezoidal corrugated beam, which is reinforced by shape memory alloy sheets on both sides. Formulas are presented for shape memory alloys in states of compression and tension. According to the modified Brinson model, shape memory alloys have different thermomechanical behavior in compression and tension, and also these alloys would behave differently in different temperatures. The developed formulation is based on Euler–Bernoulli theory. Deflection of the smart structure and the effect of asymmetric response in shape memory alloys are studied. Results found from the semi-analytic modeling are compared to and validated through a finite element modeling, and there is more than [Formula: see text] agreement between two solutions. With regard to the results, the neutral axis of the smart structure changes in each section. The maximum deflection ratio of asymmetric mode to symmetric one mode is 1.7. Additionally, the effect of design parameters on deflection is studied in detail.

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