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.

Design, analysis, and manufacture of a tension–compression self-centering damper based on energy dissipation of pre-stretched superelastic shape memory alloy wires

2017 ◽  
Vol 28 (15) ◽  
pp. 2129-2139 ◽  
Author(s):  
Amin Alipour ◽  
Mahmoud Kadkhodaei ◽  
Mohsen Safaei
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damping Ratio ◽  
Dissipated Energy ◽  
Damping Capacity ◽  
Compression Tests ◽  
Mechanical Unloading ◽  
Tension And Compression ◽  
The Individual

Superelastic shape memory alloys dissipate significant amount of energy since they recover large transformation strains upon mechanical unloading. Due to their dissipation properties, shape memory alloys can be effectively employed as dampers. Design, simulation, and fabrication of a newly developed superelastic shape memory alloy damper are discussed in this article. To enhance the stroke and dissipation capacity of the proposed damper, a system is implemented which operates more efficiently than a single shape memory alloy wire. Although shape memory alloy wires can only undergo tension, the new system enables the damper to be loaded in both tension and compression. Two damping groups are employed in this mechanism: one of which is activated during tension and the other is activated during compression of the damper. Each damping group consists of two shape memory alloy wires acting in the opposite directions to increase the damping capacity of the system. The mechanical responses of the individual components as well as the assembled damper are simulated. The predicted performance of the damper is then validated through tension/compression tests on the fabricated sample. Numerical and experimental force–displacement curves are also shown to be in a good agreement. The effect of different parameters on damping ratio and dissipated energy of the presented damper is investigated.

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.

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

Implementation of Shape Memory Alloys as Active Elements in Injuries Recuperative Equipment

2014 ◽  
Vol 657 ◽  
pp. 392-396
Author(s):  
Adela Ursanu Dragoş ◽  
Sergiu Stanciu ◽  
Nicanor Cimpoeşu ◽  
Mihai Dumitru ◽  
Ciprian Paraschiv
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Spinal Cord Injuries ◽  
Good Alternative ◽  
Careful Consideration ◽  
Damping Capacity ◽  
Loss Of Function ◽  
User Friendliness ◽  
Wide Range ◽  
Constructive Models

Entire or partial loss of function in the shoulder, elbow or wrist represent an increasingly common ailment connected to a wide range of injuries or other conditions including sports, occupational, spinal cord injuries or strokes. A general treatment of these problems relies on physiotherapy procedures. An increasing number of metallic materials are continuously being developed to expect the requirements for different engineering applications including biomedical field. Few constructive models that can involve intelligent materials are analyzed to establish the advantages in usage of shape memory elements mechanical implementation. The shape memory effect, superelasticity and damping capacity are unique characteristics at metallic alloys which demand careful consideration in both design and manufacturing processes. The actual rehabilitation systems can be improved using smart elements in motorized equipments like robotic systems. Shape memory alloys, especially NiTi (nitinol), represent a very good alternative for actuation in equipments with moving dispositive based on very good actuation properties, low mass, small size, safety and user friendliness. In this article the actuation and the force characteristics were analyzed to investigate a relationship between the bending angle and the actuation real value.

Effect of Heat Treatments on the Damping Characteristics of TiNi-Based Shape Memory Alloys

2006 ◽  
Vol 319 ◽  
pp. 33-38 ◽  
Author(s):  
I. Yoshida ◽  
Kazuhiro Otsuka
Keyword(s):  
Internal Friction ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Low Frequency ◽  
Heat Treatments ◽  
Damping Capacity ◽  
Temperature Hysteresis ◽  
Temperature Spectrum ◽  
Two Peaks ◽  
Very High

Low frequency internal friction of Ti49Ni51 binary and Ti50Ni40Cu10 ternary shape memory alloys has been measured. The effect of solution and aging heat treatments on the damping property was examined. The temperature spectrum of internal friction for TiNi binary alloy consists, in general, of two peaks; one is a transition peak which is associated with the parent-martensite transformation and is rather unstable in a sense that it strongly depends on the frequency and decreases considerably when held at a constant temperature. The other one is a very high peak of the order of 10-2, which appears at around 200K. It appears both on cooling and on heating with no temperature hysteresis, and is very stable. The behavior of the peak is strongly influenced by the heat treatments. The trial of two-stage aging with a purpose of improving the damping capacity has been proved unsatisfactory. TiNiCu has a very high damping, the highest internal friction reaching 0.2, but by quenching from very high temperature, say 1373K, the damping is remarkably lowered. For the realization of high damping the quenching from a certain temperature range around 1173K seems the most preferable condition.

Design of Shape Memory Alloy Springs With Applications in Vibration Control

1993 ◽  
Vol 115 (1) ◽  
pp. 129-135 ◽  
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.

Mechanics of nickel–titanium shape memory alloys undergoing partially constrained recovery for self-healing materials

2018 ◽  
Vol 29 (15) ◽  
pp. 3025-3036 ◽  
Author(s):  
Nathan Salowitz ◽  
Ameralys Correa ◽  
Trishika Santebennur ◽  
Afsaneh Dorri Moghadam ◽  
Xiaojun Yan ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Self Healing ◽  
Bonding Agents ◽  
Compressive Loads ◽  
Martensitic State ◽  
Geometric Changes ◽  
Shape Memory Fibers

Engineered self-healing materials seek to create an innate ability for materials to restore mechanical strength after incurring damage, much like biological organisms. This technology will enable the design of structures that can withstand their everyday use without damage but also recover from damage due to an overload incident. One of the primary mechanisms for self-healing is the incorporation of shape memory fibers in a composite type structure. Upon activation, these shape memory fibers can restore geometric changes caused by damage and close fractures. To date, shape memory–based self-healing, without bonding agents, has been limited to geometric restoration without creating a capability to withstand externally applied tensile loads due to the way the shape memory material has been integrated into the composite. Some form of bonding has been necessary for self-healing materials to resist an externally applied load after healing. This article presents results of new study into using a form of constrained recovery of nickel–titanium shape memory alloys in self-healing materials to create residual compressive loads across fractures in the low temperature martensitic state. Analysis is presented relating internal loads in self-healing materials, potentially generated by shape memory alloys, to the capability to resist externally applied loads. Supporting properties were experimentally characterized in nickel–titanium shape memory alloy wires. Finally, self-healing samples were synthesized and tested demonstrating the ability to resist externally applies loads without bonding. This study provides a new useful characterization of nickel–titanium applicable to self-healing structures and opens the door to new forms of healing like incorporation of pressure-based bonding.

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.

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