Damping Characteristics of Cold-Rolled and Annealed Equiatomic TiNi Shape Memory Alloy

Damping capacity and storage modulus of cold-rolled and annealed Ti50Ni50 SMA are systematically investigated by DSC and DMA tests. The specimens annealed at 500 oC for 1 ~ 72 h and annealed at 650 oC for short time can all reach a high tan δ value and a deep storage modulus minimum during B2→R transformation. This reveals that the occurrence of R-phase can strongly soften the storage modulus and thus promote the damping capacity of Ti50Ni50 SMA. The specimens anneaed at 650 oC for longer time have a lower tan δ value due to the diminishing of R-phase formation. Therefore, a good damping capacity associated with a significant softening storage modulus can be acquired by suitably control the annealing conditions of cold-rolled Ti50Ni50 to generate adequate of R-phase premartensite.

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Processing of Single-Stage Bellows of TiNi Shape Memory Alloy Using Rubber Bulge Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.2059 ◽

2005 ◽

Vol 475-479 ◽

pp. 2059-2062 ◽

Cited By ~ 3

Author(s):

Hiromasa Semba ◽

Nagatoshi Okabe ◽

Toru Yamaji ◽

Keisuke Okita ◽

Kiyoshi Yamauchi

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Cold Working ◽

Large Strain ◽

Longitudinal Direction ◽

Single Stage ◽

Damping Characteristics ◽

Annealing Conditions ◽

New Type ◽

Typical Shape

The bellows formed of TiNi shape memory alloy is proposed as a new type of seismic protection device. The bellows structure is known to have lower rigidity along the longitudinal direction through effect of its shape. On the other hand, TiNi is known to be one of the most typical shape memory alloys, which have high damping characteristics for dynamics engaged in its twin formation under martensite state and have the ability to recover completely from the large strain (even such as 8%) after unloaded and or heated. This paper describes a processing method of a single-stage bellows of TiNi shape memory alloy using rubber bulge method. Thin-walled TiNi tubes subjected to cold working were prepared. Several annealing conditions for the process were examined and the appropriate one was discussed. Then the rubber bulge method of displacement control was introduced. Finally, the procedure of the process including heat treatment was clarified.

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High Damping Capacity of a Binary TiNi Shape Memory Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.687.485 ◽

2011 ◽

Vol 687 ◽

pp. 485-489

Author(s):

Zhi Shan Yuan ◽

Zhao Wei Feng ◽

Wei Dong Miao ◽

Jiang Bo Wang ◽

Jin Zhou ◽

...

Keyword(s):

Phase Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Storage Modulus ◽

Loss Modulus ◽

Parent Phase ◽

Damping Capacity ◽

Quenching Rate ◽

Scanning Calorimetry

TiNi shape memory alloys exhibiting high damping capacity are currently expected to be used as structural materials for energy dissipation or vibration control applications. In this paper, the characterization of damping behaviour of a binary TiNi SMA was performed by dynamic mechanical analyzer (DMA) instrument and differential scanning calorimetry (DSC) equipment. Damping tests measuring Tanδ, storage modulus E' and loss modulus E" of Ti49.2Ni50.8 binary shape memory alloy were investigated at different temperature, using different frequency and strain amplitude. It shows that quenching rate has a significant effect on the damping capacity of TiNi SMA by exhibiting different phase transformation behavior. Internal friction values (Q-1) corresponding to cubic B2 parent phase to rhombohedral R phase transformation, B2-R, and R-B19' monoclinic martensite transformation are as high as 0.177 and 0.078, respectively. The occurrence of R-phase significantly softens the storage modulus and thus promotes the damping capacity of TiNi SMAs.

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Mechanical Consequences of Dynamically Loaded NiTi Wires under Typical Actuator Conditions in Rehabilitation and Neuroscience

Journal of Functional Biomaterials ◽

10.3390/jfb12010004 ◽

2021 ◽

Vol 12 (1) ◽

pp. 4

Author(s):

Umut D. Çakmak ◽

Zoltán Major ◽

Michael Fischlschweiger

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Storage Modulus ◽

Loss Factor ◽

Empirical Relation ◽

Material Behavior ◽

Chemical Compositions ◽

Loading Frequency ◽

Frequency Dependency ◽

Controlled Conditions

In the field of rehabilitation and neuroscience, shape memory alloys play a crucial role as lightweight actuators. Devices are exploiting the shape memory effect by transforming heat into mechanical work. In rehabilitation applications, dynamic loading of the respective device occurs, which in turn influences the mechanical consequences of the phase transforming alloy. Hence in this work, dynamic thermomechanical material behavior of temperature-triggered phase transforming NiTi shape memory alloy (SMA) wires with different chemical compositions and geometries was experimentally investigated. Storage modulus and mechanical loss factor of NiTi alloys at different temperatures and loading frequencies were analyzed under force-controlled conditions. Counterintuitive storage modulus- and loss factor-dependent trends regarding the loading frequency dependency of the mechanical properties on the materials’ composition and geometry were, hence, obtained. It was revealed that loss factors showed a pronounced loading frequency dependency, whereas the storage modulus was not affected. It was shown that force-controlled conditions led to a lower storage modulus than expected. Furthermore, it turned out that a simple empirical relation could capture the characteristic temperature dependency of the storage modulus, which is an important input relation for modeling the rehabilitation device behavior under different dynamic and temperature loading conditions, taking directly into account the material behavior of the shape memory alloy.

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Microstructure and damping characteristics of Ti50Ni24.9Cu25Y0.1 shape memory alloy

Materials Letters ◽

10.1016/j.matlet.2012.12.086 ◽

2013 ◽

Vol 95 ◽

pp. 125-127 ◽

Cited By ~ 5

Author(s):

Y.Y. Luo ◽

Y.Q. Zhao ◽

Y.F. Lu ◽

Z.P. Xi ◽

W.D. Zeng

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Damping Characteristics

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Rate-Dependent Damping Capacity of NiTi Shape Memory Alloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.172-174.37 ◽

2011 ◽

Vol 172-174 ◽

pp. 37-42 ◽

Cited By ~ 2

Author(s):

Yong Jun He ◽

Qing Ping Sun

Keyword(s):

Shape Memory Alloy ◽

Strain Rate ◽

Shape Memory ◽

Strain Curve ◽

Tensile Loading ◽

Niti Shape Memory Alloy ◽

Damping Capacity ◽

Environmental Condition ◽

Mechanical Coupling ◽

Rate Dependent

High damping capacity is one of the prominent properties of NiTi shape memory alloy (SMA), having applications in many engineering devices to reduce unwanted vibrations. Recent experiments demonstrated that, the hysteresis loop of the stress-strain curve of a NiTi strip/wire under a tensile loading-unloading cycle changed non-monotonically with the loading rate, i.e., a maximum damping capacity was obtained at an intermediate strain rate (ε.critical). This rate dependence is due to the coupling between the temperature dependence of material’s transformation stresses, latent-heat release/absorption in the forward/reverse phase transition and the associated heat exchange between the specimen and the environment. In this paper, a simple analytical model was developed to quantify these thermo-mechanical coupling effects on the damping capacity of the NiTi strips/wires under the tensile loading-unloading cycle. We found that, besides the material thermal/mechanical properties and specimen geometry, environmental condition also affects the damping capacity; and the critical strain rate ε.criticalfor achieving a maximum damping capacity can be changed by varying the environmental condition. The theoretical predictions agree quantitatively with the experiments.

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Design of Shape Memory Alloy Springs With Applications in Vibration Control

Journal of Vibration and Acoustics ◽

10.1115/1.2930305 ◽

1993 ◽

Vol 115 (1) ◽

pp. 129-135 ◽

Cited By ~ 44

Author(s):

C. Liang ◽

C. A. Rogers

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Vibration Control ◽

Young’S Modulus ◽

Young's Modulus ◽

Design Method ◽

Control Area ◽

Spring Constant ◽

Damping Capacity

Shape memory alloys (SMAs) have several unique characteristics, including their Young’s modulus-temperature relations, shape memory effects, and damping characteristics. The Young’s modulus of the high-temperature austenite of SMAs is about three to four times as large as that of low-temperature martensite. Therefore, a spring made of shape memory alloy can change its spring constant by a factor of three to four. Since a shape memory alloy spring can vary its spring constant, provide recovery stress (shape memory effect), or be designed with a high damping capacity, it may be useful in adaptive vibration control. Some vibration control concepts utilizing the unique characteristics of SMAs will be presented in this paper. Shape memory alloy springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some design approaches based upon linear theory have been proposed for shape memory alloy springs. A more accurate design method for SMA springs based on a new nonlinear thermomechanical constitutive relation of SMA is also presented in this paper.

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On a Finger Model Actuated With Shape Memory Alloy Artificial Muscles

Dynamic Systems and Control, Volumes 1 and 2 ◽

10.1115/imece2003-41064 ◽

2003 ◽

Author(s):

Veturia Chiroiu ◽

Ligia Munteanu ◽

Traian Badea ◽

Cornel Mihai Nicolescu

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Aluminum Matrix ◽

Electrical Current ◽

Longitudinal Axis ◽

Damping Capacity ◽

Artificial Muscles ◽

Niti Wires ◽

Finger Model ◽

Start Temperature

The simulation of a flexible finger, actuated with the shape memory alloys (SMAs) artificial muscles, is presented in the paper. The finger is modeled as a cylindrically rod with three embedded NiTi wires in a n aluminum matrix. Forces between NiTi wires causes bending in any plane perpendicular to the longitudinal axis of the finger. The NiTi wires are heated above the austenitic start temperature by passing an electrical current, and the deflected wire tends to return to the initial configuration. Using characteristics of SMAs such as high damping capacity, super-elasticity, thermo-mechanical behavior and shape memory, the actuation for the finger is theoretically introduced and discussed.

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