Damping Properties of SMA

2008 ◽  
Vol 583 ◽  
pp. 85-109 ◽  
Author(s):  
Sergey Kustov ◽  
Jan Van Humbeeck
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damping Capacity ◽  
Damping Properties ◽  
Internal Defects ◽  
Niti Alloys ◽  
Martensitic State ◽  
Martensitic Variants ◽  
Made In

This chapter analyzes applicability of different models of anelasticity to damping capacity of shape memory alloys both in the martensitic state and during the martensitic transformation. The chapter focuses mainly on recent observations made in Cu-based and NiTi alloys. From the latest works it is evident that the high damping capacity can not only be related to the hysteretic mobility of interfaces between martensitic variants but may be associated as well with internal defects of variants.

Influence of Cobalt Addition on Microstructure and Damping Properties of Cu-Al-Ni Shape Memory Alloys

2020 ◽  
Vol 1010 ◽  
pp. 34-39
Author(s):  
Ying Ci Wee ◽  
Hamidreza Ghandvar ◽  
Tuty Asma Abu Bakar ◽  
Esah Hamzah
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Elastic Anisotropy ◽  
Mechanical Analysis ◽  
Damping Capacity ◽  
Damping Properties ◽  
Additional Element ◽  
Lower Temperature ◽  
Co Addition ◽  
High Degree

Copper-based shape memory alloys (SMAs) gaining attention due to their high damping properties during martensitic transformation and effective in energy dissipation which is applicable to damping application. However, copper-based SMAs such as the ternary Cu-Al-Ni are not easily deformed in the lower temperature martensitic phase which can be attributed to brittleness induced by coarse grain size, high degree of order and elastic anisotropy. Hence, this study aims to improve the properties of Cu-Al-Ni SMAs by addition of fourth alloying element. In this research, Cu-Al-Ni alloys with the addition of the fourth additional element, cobalt were prepared by casting. Microstructure characteristics of Cu-Al-Ni SMAs with and without Co addition were investigated via scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD). Damping capacity was determined by dynamic mechanical analysis (DMA). It was found that the alloy with 0.7wt% of Co addition showed the best improvement on the damping properties.

Investigations on the Amplitude-Dependent Damping Behavior of Superelastic Shape Memory Alloys

2012 ◽  
Author(s):  
Jonas Böttcher ◽  
Marcus Neubauer ◽  
Jörg Wallaschek
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damping Ratio ◽  
Harmonic Approximation ◽  
Harmonic Balance Method ◽  
Damping Capacity ◽  
Memory Element ◽  
Strain Characteristic ◽  
Force Signal ◽  
Martensitic State

The nonlinear, hysteretic stress-strain characteristic of superelastic shape memory alloys (SMA) results in energy dissipation and therefore in high damping capacities. Due to the nonlinearity the damping capacity strongly depends on the amplitude of the applied excitation. In this work, a rheological non-smooth model is used to describe the principle behavior of superelastic SMA undergoing harmonic displacements. The equivalent mechanical model consists of a spring representing the elastic deformation of the superelastic SMA in austenitic and detwinned martensitic state. A friction element represents the stress plateaus for forward and backward transformation between austenitic and martensitic state. A constant force is applied to the system to generate an offset which shifts the hysteresis to positive force values. Two mechanical stops are implemented to describe the end of the stress plateaus and therefore correspond to the strain differences of the stress levels for forward and backward transformation. Thus, the system behavior is highly amplitude-dependent. A harmonic approximation of the force generated by the superelastic SMA element during one excitation period is calculated by applying the Harmonic Balance Method to the nonlinear force signal of the rheological model. In this context the Fourier coefficients are calculated by performing a piecewise integration of the force signal. The Integrals are being calculated for each steady interval. The equivalent stiffness and damping coefficients are given for this approximation as functions of excitation amplitude and the system parameters. Based on these results, the damping capacity of a superelastic shape memory element undergoing harmonic displacements is presented using an analytical expression for the damping ratio.

Multi-stage martensitic transformation in Ni-rich NiTi shape memory alloys

2017 ◽  
Vol 10 (01) ◽  
pp. 1740004 ◽  
Author(s):  
Xiebin Wang ◽  
Bert Verlinden ◽  
Sergey Kustov
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Precipitation Hardening ◽  
Aging Treatment ◽  
Functional Stability ◽  
Transformation Behavior ◽  
Niti Alloys ◽  
Multi Stage ◽  
Niti Shape Memory Alloys

Precipitation hardening is an effective way to improve the functional stability of NiTi shape memory alloys. The precipitates, mainly Ni4Ti3, could be introduced by aging treatment in Ni-rich NiTi alloys. However, the presence of Ni4Ti3 precipitates could disturb the transformation behavior, resulting in the multi-stage martensitic transformation (MMT). With the presence of MMT, it is difficult to control the transformation behavior, and thus limits the applicability of NiTi alloys. In this work, previous efforts on explaining the observed MMT are summarized. The difficulties in developing a unified explanation are discussed, and a possible way to avoid the MMT is proposed.

Damping Properties of Magnetically Ordered Shape Memory Alloys

2016 ◽  
Vol 845 ◽  
pp. 77-82
Author(s):  
Vladimir V. Khovaylo ◽  
Valeria Rodionova ◽  
Sergey Taskaev ◽  
Anna Kosogor
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Solid Phase ◽  
High Mobility ◽  
Damping Capacity ◽  
Intermetallic Alloys ◽  
Damping Properties ◽  
Damping Materials ◽  
Alloys And Compounds ◽  
Magnetically Ordered

Intermetallic alloys and compounds undergoing diffusionless solid–solid phase transformations are an important class of high-damping materials. Some representatives of these alloys and compounds also possess good magnetic properties. For such materials, a combination of the magnetoelastic coupling and a high mobility of the martensitic variants can bring about new features of the internal friction and allows one to control the damping capacity by an external magnetic field. Here we review damping properties of magnetically ordered shape memory alloys.

The Overlooked Hydrogen Effect in Ti-Ni-Based Shape Memory Alloys

2011 ◽  
Vol 687 ◽  
pp. 533-538 ◽  
Author(s):  
Gen Lian Fan ◽  
Zhi Qiang Li ◽  
Di Zhang ◽  
Xiao Bing Ren
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Specific Effect ◽  
Atomic Radius ◽  
Hydrogen Effect ◽  
Boundary Interaction ◽  
Martensitic State ◽  
Damping Materials ◽  
Damping Peak

Having the smallest atomic radius, hydrogen can easily enter into many metals either by intentional doping or by inadvertent exposure to humid air. For Ti-Ni-based shape memory alloys, our recent studies have shown a specific effect of hydrogen in this important class of alloys, i.e., the interaction between hydrogen and twin boundaries can result in a very high damping peak in the martensitic state; thus hydrogen can be utilized to develop high damping materials. In the present study, aiming to provide a more comprehensive investigation to the role of hydrogen in Ti-Ni-based shape memory alloys, we systematically studied the hydrogen effect on martensitic transformation behavior, and twinning stress. By comparing the results from two sets of samples, one with and another without hydrogen, we obtained the following results. Firstly, hydrogen can lower the martensitic transformation temperature and reduce the transformation heat. Secondly, the twinning stress increases with hydrogen doping, and a typical yielding was found in the tensile testing for the sample containing hydrogen, which is absent in the H-free sample. This indicates that the hydrogen-twin boundary interaction also affect dc mechanical properties.

Atomic Order and Martensitic Transformation in Cu-Al-Be Shape Memory Alloys

1995 ◽  
Vol 05 (C8) ◽  
pp. C8-973-C8-978
Author(s):  
M. Jurado ◽  
Ll. Mañosa ◽  
A. González-Comas ◽  
C. Stassis ◽  
A. Planes
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Atomic Order

The High Damping Capacity of Shape Memory Alloys

1995 ◽  
Vol 86 (3) ◽  
pp. 176-183
Author(s):  
Jan Van Humbeeck ◽  
Johannes Stoiber ◽  
Luc Delaey ◽  
Rolf Gotthardt
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damping Capacity

scholarly journals Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Bauer ◽  
M. Vollmer ◽  
T. Niendorf
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Boundaries ◽  
Tensile Tests ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Grain Orientations ◽  
High Degree

AbstractIn situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is shown that grain boundaries lead to stress concentrations and, thus, to formation of unfavored martensite variants. Moreover, some martensite plates seem to penetrate the grain boundaries resulting in a high degree of irreversibility in this area. However, after a stable microstructural configuration is established in direct vicinity of the grain boundary, the transformation begins inside the neighboring grains eventually leading to a sequential transformation of all grains involved.

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