Shape Memory Alloys for Seismic Response Modification: A State-of-the-Art Review

2005 ◽  
Vol 21 (2) ◽  
pp. 569-601 ◽  
Author(s):  
John C. Wilson ◽  
Michael J. Wesolowsky
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Seismic Response ◽  
Earthquake Engineering ◽  
Materials Science ◽  
State Of The Art ◽  
High Strength ◽  
High Energy ◽  
Hysteretic Behavior ◽  
Seismic Engineering

Shape memory alloys (SMAs) are a remarkable class of metals that can offer high strength, large energy dissipation through hysteretic behavior, extraordinary strain capacity (up to 8%) with full shape recovery to zero residual strain, and a high resistance to corrosion and fatigue—aspects that are all desirable from an earthquake engineering perspective. Their various physical characteristics result from solid-solid transformation between austenite and martensite phases of the alloy that may be induced by stress or temperature. The most commercially successful SMA is a binary alloy of nickel and titanium (NiTi). Although SMAs are expensive relative to most other materials used in seismic engineering, in certain forms their capacity for high energy loss per unit volume means that comparatively small quantities can be made to be especially effective, for example when used in wire form as part of a seismic bracing system. This state-of-the-art paper presents current materials science aspects, material models, and mechanical behavior of SMAs relevant to seismic engineering, and examines the current state of design of SMA-based seismic response modification devices and their use in buildings and bridges. SMA-based devices offer promising advantages for development of next-generation seismic protection systems.

scholarly journals A Constitutive Model for Superelastic Shape Memory Alloys Considering the Influence of Strain Rate

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Hui Qian ◽  
Hongnan Li ◽  
Gangbing Song ◽  
Wei Guo
Keyword(s):  
Energy Dissipation ◽  
Constitutive Equation ◽  
Shape Memory Alloys ◽  
Strain Rate ◽  
Shape Memory ◽  
Functional Materials ◽  
Tensile Tests ◽  
Hysteretic Behavior ◽  
Seismic Engineering ◽  
Energy Dissipation Devices

Shape memory alloys (SMAs) are a relatively new class of functional materials, exhibiting special thermomechanical behaviors, such as shape memory effect and superelasticity, which enable their applications in seismic engineering as energy dissipation devices. This paper investigates the properties of superelastic NiTi shape memory alloys, emphasizing the influence of strain rate on superelastic behavior under various strain amplitudes by cyclic tensile tests. A novel constitutive equation based on Graesser and Cozzarelli’s model is proposed to describe the strain-rate-dependent hysteretic behavior of superelastic SMAs at different strain levels. A stress variable including the influence of strain rate is introduced into Graesser and Cozzarelli’s model. To verify the effectiveness of the proposed constitutive equation, experiments on superelastic NiTi wires with different strain rates and strain levels are conducted. Numerical simulation results based on the proposed constitutive equation and experimental results are in good agreement. The findings in this paper will assist the future design of superelastic SMA-based energy dissipation devices for seismic protection of structures.

Adaptive Elastic SMA Elements for Damping Applications

2013 ◽  
Author(s):  
Alexander Czechowicz ◽  
Peter Dültgen ◽  
Sven Langbein
Keyword(s):  
Boundary Conditions ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Electrical Resistance ◽  
Thermal Activation ◽  
Hysteretic Behavior ◽  
Damping Function ◽  
Actual Shape ◽  
Elastic Elements

Shape memory alloys (SMA) are smart materials, which have two technical usable effects: While pseudoplastic SMA have the ability to change into a previously imprinted actual shape through the means of thermal activation, pseudoelastic SMA show a reversible mechanical elongation up to 8% at constant temperature. The transformation between the two possible material phases (austenite and martensite) shows a hysteretic behavior. As a result of these properties, SMA can be used as elastic elements with intrinsic damping function. Additionally the electrical resistance changes remarkably during the material deformation. These effects are presented in the publication in combination with potential for applications in different branches at varying boundary conditions. The focus of the presented research is concentrated on the application of elastic elements with adaptive damping function. As a proof for the potential considerations, an application example sums up this presentation.

Shape Memory Alloys Wires: From Small to Medium Diameter

2016 ◽  
Vol 101 ◽  
pp. 79-88 ◽  
Author(s):  
Vicenç Torra ◽  
Sara Casciati ◽  
Michele Vece
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Mechanical Energy ◽  
Critical Discussion ◽  
Point Of View ◽  
Hysteretic Behavior ◽  
External Temperature ◽  
Cold Temperatures ◽  
Thin Wires ◽  
Different Diameters

The use of Shape Memory Alloys in dampers devices able to reduce the wind, rain or traffic induced oscillations in stayed cables is well represented in the literature. An analysis realized on standard cables at existing facilities shows the reliable efficiency of the SMA wire in damping oscillations. Such studies also provide tools to build the SMA dampers and to account for the effects of the external temperature in the SMA. The particular study reported in this paper focuses on a critical discussion on the relation between the wire diameter and macroscopic behavior and external temperature effects. The damping requires the absorption of the mechanical energy and its conversion to heat via the action of hysteresis cycles. The study was realized on wires of different diameters. In particular, the study centers on wires of diameter 0.2, 0.5 and 2.46 mm. The flat cycles showed by the thin wires (i.e., diameter 0.2 and 0.5 mm) and the non-classical S-shaped cycles of wires of diameter 2.46 mm establish clear differences of the response under external summer-winter temperature actions. Depending of the room temperature and SMA composition, a complete flat transformation in thin wires requires stresses, in general, near 300-400 MPa. A complete transformation for an S-shaped cycle need stresses as higher as 600 MPa. The analysis of the behavior of these wires under the action of warm temperatures in summer and cold temperatures in winter, suggests that thin wires lose their pseudo-elastic state in winter. The S-shaped permits positive working in extended temperature domain and a supplementary investigation establishes that S-shaped can be increased by strain aging. The hysteretic behavior in S-shaped permits practical working under external temperatures as applications in bridges require. From a fundamental point of view, the flat cycles are coherent with the classical treatment of the SMA as a first order phase transition but the S-shaped can be considered associated to an anomaly in heat capacity.

Development of High-Strength, Fine, and Ultrafine-Grained Shape Memory Alloys

2018 ◽  
Vol 119 (13) ◽  
pp. 1346-1349
Author(s):  
V. G. Pushin ◽  
N. N. Kuranova ◽  
A. V. Pushin
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Strength ◽  
Ultrafine Grained

A Macromechanical Constitutive Model of Shape Memory Alloys Under Uniaxial Cyclic Loading

2012 ◽  
Vol 28 (3) ◽  
pp. 469-477 ◽  
Author(s):  
H. Lei ◽  
B. Zhou ◽  
Z. Wang ◽  
Y. Wang
Keyword(s):  
Cyclic Loading ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Hysteretic Behavior ◽  
Test Results ◽  
Model Match ◽  
Number Of Cycles ◽  
The Relationship

AbstractIn this paper, the thermomechanical behavior of shape memory alloys (SMAs) subjected to uniaxial cyclic loading is investigated. To obtain experimental data, the strain-controlled cyclic loading-unloading tests are conducted at various strain-rates and temperatures. Dislocations slip and deformation twins are considered to be the main reason that causes the unique cyclic mechanical behavior of SMAs. A new variable of shape memory residual factor was introduced, which will tend to zero with the increasing of the number of cycles. Exponential form equations are established to describe the evolution of shape memory residual factor, elastic modulus and critical stress, in which the influence of strain-rate, number of cycles and temperature are taken into account. The relationship between critical stresses and temperature is modified by considering the cycling effect. A macromechanical constitutive model was constructed to predict the cyclic mechanical behavior at constant temperature. Based on the material parameters obtained from test results, the hysteretic behavior of SMAs subjected to isothermal uniaxial cyclic loading is simulated. It is shown that the numerical results of the modified model match well with the test results.

A uniaxial constitutive model for NiTi shape memory alloy bars considering the effect of residual strain

2019 ◽  
Vol 30 (8) ◽  
pp. 1163-1177
Author(s):  
Canjun Li ◽  
Zhen Zhou ◽  
Yazhi Zhu
Keyword(s):  
Shape Memory Alloy ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Residual Strain ◽  
Hysteretic Behavior ◽  
Niti Shape Memory Alloy ◽  
Strain Effect ◽  
Proposed Model ◽  
Residual Strains

Super-elastic shape memory alloys are widely used in structural engineering fields due to their encouraging super-elasticity and energy dissipation capability. Large-size shape memory alloy bars often present significant residual strains after unloading, which emphasizes the necessity of developing a residual strain effect–coupled constitutive model to predict well the performance of shape memory alloy–based structures. First, this article experimentally studies the hysteretic behavior of NiTi shape memory alloy bars under quasi-static loading conditions and investigates the effects of cyclic numbers and strain amplitudes on residual strain. Second, a concept of cumulative transformation strain is preliminarily introduced into a phenomenological Lagoudas model. A uniaxial constitutive model for shape memory alloy bars including the residual strain is proposed. By using OpenSees platform, numerical simulations of shape memory alloy bars are conducted—the results of which indicate that the proposed model can accurately capture the hysteretic behavior of shape memory alloys. The predicted residual strains show a good agreement to experimental results, which demonstrates the desirable efficiency of the proposed model.

scholarly journals Influence of Structural Defects on the Properties of Metamagnetic Shape Memory Alloys

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1131
Author(s):  
J. I. Pérez-Landazábal ◽  
V. Sánchez-Alarcos ◽  
V. Recarte ◽  
O. A. Lambri ◽  
F. G. Bonifacich ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Entropy Change ◽  
High Energy ◽  
Milling Process ◽  
Structural Defects ◽  
Internal Stresses ◽  
Spin Glass Behavior ◽  
Deformed State

The production of μ-particles of Metamagnetic Shape Memory Alloys by crushing and subsequent ball milling process has been analyzed. The high energy involved in the milling process induces large internal stresses and high density of defects with a strong influence on the martensitic transformation; the interphase creation and its movement during the martensitic transformation produces frictional contributions to the entropy change (exothermic process) both during forward and reverse transformation. The frictional contribution increases with the milling time as a consequence of the interaction between defects and interphases. The influence of the frictional terms on the magnetocaloric effect has been evidenced. Besides, the presence of antiphase boundaries linked to superdislocations helps to understand the spin-glass behavior at low temperatures in martensite. Finally, the particles in the deformed state were introduced in a photosensitive polymer. The mechanical damping associated to the Martensitic Transformation (MT) of the particles is clearly distinguished in the produced composite, which could be interesting for the development of magnetically-tunable mechanical dampers.

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