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1
Content available Mechanical properties and advanced subjects in shape memory alloys and polymers
Matsui R., Takeda K., Tobushi H., Pieczyska E. A.
Journal of Theoretical and Applied Mechanics
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2018
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Vol. 56 nr 2
447--456
EN
Advanced subjects in mechanical properties of shape memory alloys and polymers are discussed. In the subloop loading under a stress-controlled condition of the shape memory alloy, the transformation-induced stress relaxation appears due to variation in temperature. The enhancement of corrosion and corrosion fatigue life of the shape memory alloy is discussed. The development of a functionally-graded shape memory alloy and polymer is expected to obtain better performance. Three-way motion appears in the shape memory composite with the shape memory alloy and polymer.
2
Content available remote Reliability of stiffness measurement device during passive isokinetic spastic wrist movements of healthy subjects and hemiplegics
Orand A., Miyasaka H., Takeda K., Tanino G., Chihara T., Beppu H., Sonoda S.
Biocybernetics and Biomedical Engineering
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2017
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Vol. 37, no. 1
114--123
EN
The consistency of torque measurements during repetitive moving arm movements and also during passive wrist movements at two angular velocities of slow (~6°/s) and moderate (~120°/s) was investigated. The designed and developed device was applied to 3 cases, to a spring, to 8 able-bodied subjects and to 2 hemiplegic patients. While the mean of the intraclass correlation coefficient of subjects were 0.65 and 0.75 for slow and moderate angular velocities, those of the hemiplegic patients and the spring respectively ranged between excellent values of 0.93–1 and 0.91–1. The Pearson's product-moment correlation coefficients of the 3 cases for the 2 slow and moderate angular velocities ranged between 0.80 and 1. We could verify that the device can be used in our future researches and it can (1) reliably rotate a moving arm horizontally with angular velocities between 3 and 350°/s constantly in a range of motion between -60 and 60° and (2) simultaneously capture the data of angular displacement, torque, and two electromyogram activities. For the standardization of our future studies with the device, we could verify the stability of the last two repeated passive wrist movements in case of patients. The results of the study with the able-bodied subjects are also important as a reference for our studies with the hemiplegic.
3
Content available remote Torsional deformation properties of SMA tapes and their application to bias-type reciprocating rotary driving actuator
Takeda K., Matsui R., Tobushi H., Pieczyska E. A.
Archives of Mechanics
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2017
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Vol. 69, nr 4-5
289--303
EN
In order to develop the reciprocating rotary driving actuator with a simple mechanism using shape memory alloy (SMA) tapes, the graphical method to design the actuator was proposed based on the torsional deformation properties of SMA tapes. The torsional deformation properties of the SME tape showing the shape memory effect (SME) and the SE tape showing superelasticity (SE) were obtained. The bias-type reciprocating rotary actuator was composed of the pretwisted SME tape and the flat SE tape in series. The design chart expressed by the relationship between torque and twisting angle of the SME tape and the SE tape was proposed. The rotational angle and torque, which vary depending on temperature, can be estimated based on the design chart. The rotational angle is controlled by adjusting the mounting angle of the SME tape and the heating temperature. The automatically opening and closing blind driven by sunlight was demonstrated. The blind was controlled by using the reciprocating rotary element composed of the SME tape and the SE tape. The behavior of the blind can be achieved based on the proposed design method of the reciprocating rotary driving element.
4
Content available remote Enhancement of bending fatigue life in TiNi shape-memory alloy tape by nitrogen ion implantation
Takeda K., Matsui R., Tobushi H., Homma S., Levintant-Zayonts N., Kucharski S.
Archives of Mechanics
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2015
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Vol. 67, nr 4
293--310
EN
A shape-memory alloy (SMA) is expected to be applied as intelligent or smart material since it shows the functional characteristics of the shape memory effect and superelasticity. Most SMA elements, with these characteristics, perform cyclic motions. In these cases, the fatigue property of SMA is one of the most important issues in view of evaluating functional characteristics of SMA elements. The fatigue properties are complex since they depend on stress, strain, temperature and their hysteresis. If an SMA is implanted with high-energy ions, the thermomechanical properties of the material may change, resulting in long fatigue life. In the present study, the nitrogen ion implantation was applied to modify the surface of a TiNi SMA tape and the influence of implantation treatment on the bending fatigue properties was investigated.
5
Content available remote Influence of nitrogen ion implantation on deformation and fatigue properties of TiNi shape-memory alloy wire
Takeda K., Mitsui K., Tobushi H., Levintant-Zayonts N., Kucharski S.
Archives of Mechanics
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2013
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Vol. 65, nr 5
391--405
EN
A shape memory alloy (SMA) is expected to be applied as intelligent material since it shows the unique characteristics of the shape memory effect and superelasticity. Most SMA elements, with these characteristics, perform cyclic motions. In these cases, fatigue of SMA is one of the important properties in view of evaluating functional characteristics. The fatigue properties are complex since they depend on stress, strain, temperature and time. If SMA is implanted by high energy ions, the thermomechanical properties may change, resulting in long fatigue life. In the present study, the nitrogen ion implantation was applied to modify TiNi SMA wire surface and the influence of implantation treatment on the tensile deformation and bending fatigue properties was investigated.
6
Content available remote Creep and creep recovery under stress-controlled subloop loading in TiNi shape memory alloy
Takeda K., Matsui R., Tobushi H., Pieczyska E. A.
Archives of Mechanics
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2013
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Vol. 65, nr 5
429-444
EN
If a shape memory alloy (SMA) is subjected to the subloop loading under the stress-controlled condition, creep and creep recovery can appear based on the martensitic transformation. In the design of SMA elements, these deformation properties are important since the deflection of SMA elements can change under constant load. The conditions for the progress of the martensitic transformation are discussed based on the kinetics of the martensitic transformation for the SMA. The creep deformation properties are investigated experimentally for TiNi SMA. The creep strain rate increases in proportion to the martensitic transformation strain; the creep recovery strain rate increases in proportion to the reverse transformation strain.
7
Content available Performance and design of precision-cast shape memory alloy brain spatula
Tobushi H., Mitsui K., Takeda K.
Journal of Theoretical and Applied Mechanics
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2012
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Vol. 50 nr 3
855-869
EN
In order to develop a brain spatula made of a shape memory alloy (SMA), this paper discusses the bending characteristics of a new brain spatula precision-cast in a TiNi SMA. The results obtained can be summed up as follows. (1) With respect to an SMA-brain spatula having the same length and width as the existing type made of copper, if the new cast SMA spatula is 1.2 times as great in thickness as the existing copper spatula, or if a conventionally rolled SMA spatula is 1.3 times as great, the SMA instrument will offer the same bending rigidity and withstand almost as great a bending force as the copper one. (2) Expressing the bending fatigue life of the copper or SMA in the region of low-cycle fatigue as a power function of the maximum bending strain, the fatigue life of the SMA is longer than that of the copper. For both the cast and the rolled SMAs, the fatigue life is longer under pulsating-plane bending than under alternating plane bending.
PL
W pracy opisano problem projektowania szpatułki używanej w chirurgii mózgu, wykonanej ze stopu z pamięcią kształtu (SMA). Przedyskutowano charakterystyki zginania nowej szpatułki wykonanej z precyzyjnie odlewanego stopu TiNi. Wyniki badań podsumowano w następujący sposób: (1) w porównaniu do konwencjonalnych, miedzianych szpatułek o tej samej długości i szerokości, jeśli odlewana szpatułka SMA jest 1.2 raza grubsza od miedzianej, lub 1.3 raza, gdy wykonana została przez walcowanie, instrument ten będzie posiadał taką samą sztywność giętną i wytrzyma niemalże to samo obciążenie zginające, jak w przypadku narzędzia miedzianego; (2) wyrażając wytrzymałość zmęczeniową szpatułki miedzianej w rejonie niskocyklicznych obciążeń jako funkcję potęgową maksymalnego odkształcenia przy zginaniu, stwierdzono, że szpatułki SMA wykazują dłuższą żywotność od konwencjonalnych. W obydwu przypadkach – odlewanej i walcowanej szpatułki SMA – wytrzymałość zmęczeniowa jest większa dla płaskiego jednostronnego zginania od wytrzymałości przy zginaniu przemiennym.
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