Author
Ryosuke Matsui
Other affiliations: Hiroshima University
Bio: Ryosuke Matsui is an academic researcher from Aichi Institute of Technology. The author has contributed to research in topics: Shape-memory alloy & Shape-memory polymer. The author has an hindex of 5, co-authored 21 publications receiving 240 citations. Previous affiliations of Ryosuke Matsui include Hiroshima University.
Papers
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TL;DR: In this article, the shape-fixed foam is maintained for six months under no load at Tg− 60 K without depending on the maximum strain, and the original shape is recovered by heating thereafter.
Abstract: The thermomechanical properties of polyurethane-shape memory polymer (SMP) foams and the influence of shape-holding conditions on shape recovery were investigated experimentally. The results obtained can be summarized as follows. (1) By cooling the foam down to below the glass transition temperature Tg after compressive deformation above Tg, stress decreases and the deformed shape is fixed. By heating the shape-fixed foam up to above Tg under no load, the original shape is recovered. (2) The shape deformed above Tg is maintained for six months under no load at Tg− 60 K without depending on the maximum strain, and the original shape is recovered by heating thereafter. (3) If the deformed shape is held at high temperature, the original shape is not recovered. (4) The ratio of shape irrecovery increases in proportion to the holding strain, holding temperature and holding time.
111 citations
TL;DR: In this article, the tensile deformation and rotating-bending fatigue properties of a highelastic thin wire, a superelastic tube, and a superrelastic thin tube made of NiTi alloys were investigated experimentally.
Abstract: The tensile deformation and rotating-bending fatigue properties of a highelastic thin wire, a superelastic thin wire and a superelastic thin tube, all made of NiTi alloys, were investigated experimentally. The results obtained are summarized as follows: (I) The stress-strain curve of the highelastic thin wire is approximately linear up to a strain of 4 percent with a stress of 1400 MPa and shows little dependency on temperature and strain rate; (2) The modulus of elasticity for the initial loading stage of both the highelastic wire and the superelastic tube is low, showing superior bending flexibility as is necessary for medical applications; (3) The slopes of the strain-life curves of the alloys are steep in the low-cycle fatigue region (the strain amplitude of the fatigue limit is in the region of 0.6-0.8 percent); and (4) In the tube, fatigue cracking initiates on the rougher inner surface, resulting in a shorter fatigue life than in the case of the wire.
49 citations
TL;DR: In this article, the influence of strain ratio on bending fatigue properties of TiNi shape-memory alloy thin wires and the process of fatigue crack propagation was investigated, and the results obtained are summarized as follows.
Abstract: The influence of strain ratio on bending fatigue properties of TiNi shape-memory alloy thin wires and the process of fatigue crack propagation were investigated. The results obtained are summarized as follows. (1) The martensitic transformation stress of a superelastic thin wire is higher than that of a shape memory wire, resulting in shorter fatigue life of the superelastic wire. The maximum bending strain of fatigue limit is the martensitic-transformation starting strain. (2) The plane-bending fatigue life curve is expressed by a power function of maximum strain "max and the number of cycles to failure. The smaller the strain ratio, the shorter the fatigue life. (3) In both rotating bending and plane bending, fatigue cracks nucleate on the surface of the wire. One fatigue crack grows preferentially and the fatigue-crack propagated region of fracture surface is fan-shaped. (4) If "max is larger than 1%, "max during the rotating-bending fatigue test becomes a little smaller than that of the initial value. (5) The fatigue crack length can be estimated by measuring increase in electric resistance based on decrease in cross-sectional area due to fatigue crack propagation. (6) The fatigue crack length of the notched wire is expressed by a power function of the number of cycles.
21 citations
01 Apr 2003
TL;DR: In this paper, a fatigue test machine for alternating bending of a wire under strain-controlled conditions was developed, and the results obtained can be summarized as: (1) the fatigue life curves under alternating bending and pulsating bending, as expressed by the relationship between maximum strain and the number of cycles to failure, systematically follow the order of strain ratio.
Abstract: A fatigue-test machine for alternating bending of a wire under strain-controlled conditions was developed. Bending-fatigue tests on a TiNi shape-memory alloy wire were then performed for various strain ratios. The results obtained can be summarized as: (1) the fatigue life curves under alternating bending and pulsating bending, as expressed by the relationship between maximum strain and the number of cycles to failure, systematically follow the order of strain ratio; (2) the larger the strain ratio, the longer the fatigue life; (3) the fatigue life under rotating bending is shorter than that under alternating bending; (4) the increase in temperature during cyclic bending becomes larger in the order: rotating bending, alternating bending, pulsating bending. The fatigue life decreases in proportion to the increase in temperature; and (5) the fatigue limit of strain for alternating bending, pulsating bending and rotating bending is in the region of R-phase transformation.
14 citations
TL;DR: In this article, ultrasonic shot peening was applied to induce compressive residual stress on the surface layer of TiNi SMA tape and the influence of USP on the bending fatigue life was investigated.
Abstract: The fatigue property of shape memory alloy (SMA) is one of the most important subjects in view of evaluating functional characteristics of SMA elements. In the present study, ultrasonic shot peening (USP) was applied to induce compressive residual stress on the surface layer of TiNi SMA tape and the influence of USP on the bending fatigue life was investigated. The fatigue life of USP-treated tape is longer than that of the asreceived tape. The fatigue life of the tape USP-treated with high coverage is longer than that with low coverage. The fatigue life of the USPtreated tape increases in proportion to the hardness on the surface of the tape. [doi:10.2320/matertrans.MBW201408]
10 citations
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TL;DR: A brief review on the current progress in stimuli-responsive shape memory materials can be found in this article, where the focus is on twofold, namely newly observed ones, and novel applications with great potential at present and in near future.
864 citations
TL;DR: In this article, the authors examined the research in shape memory polymers (SMPs) composites and blends achieved by numerous research groups around the world, mainly for five aims: (1) to improve shape recovery stress and mechanical properties; (2) to decrease shape recovery induction time by increasing thermal conductivity; (3) to create new polymer/polymer blends with shape-memory effect (SME); (4) to tune switch temperature, mechanical properties, and biomedical properties of SMPs; (5) to fabricate shape memory materials sensitive to electricity,
Abstract: Shape memory polymers (SMPs) are a kind of very important smart polymers. In order to improve the properties or obtain new functions of SMPs, SMP composites and blends are prepared. We thoroughly examine the research in SMP composites and blends achieved by numerous research groups around the world. The preparation of SMPs composites and blends is mainly for five aims: (1) to improve shape recovery stress and mechanical properties; (2) to decrease shape recovery induction time by increasing thermal conductivity; (3) to create new polymer/polymer blends with shape-memory effect (SME); (4) to tune switch temperature, mechanical properties, and biomedical properties of SMPs; (5) to fabricate shape memory materials sensitive to electricity, magnetic, light and moisture. The trend of SMP composite development is discussed. SMP composites and blends exhibit novel properties that are different from the conventional SMPs and thus can be utilized in various applications.
525 citations
TL;DR: In this paper, a review of the literature on shape memory polymers (SMPs) is presented, and it is concluded that covalently crosslinked glassy thermosets appear to be better SMP candidates because of their intrinsically higher modulus, greater thermal and chemical stability, higher shape fixity and recovery, and possibly their longer cycle life.
Abstract: Many applications ranging from biomedical to aerospace have been proposed for the use of shape memory polymers (SMPs). To optimize SMPs properties for appropriately targeting such wide-spreading application requirements, it becomes necessary to understand the structure/property relationships in SMPs. The literature was reviewed and the recent advances made in the development of SMPs were determined to establish guidelines for composition and structure considerations for designing SMPs with targeted chemical, physical, and shape memory (SM) properties. It was concluded that covalently crosslinked glassy thermosets appear to be better SMP candidates because of their intrinsically higher modulus, greater thermal and chemical stability, higher shape fixity and recovery, and possibly their longer cycle life. However, material design allows for reaching comparable or better properties for all classes of SMPs. This emphasizes that optimization of SMPs requires application-specific molecular, structural, and geometrical design. Current techniques for improving stress recovery and cycle time, which compared to shape memory alloys are the two main limitations of SMPs, are extensively discussed. Understanding the relationships between the composition and structure of an SMP and its SM properties as well as its limitations enables one to better define the development areas for high performance SMPs. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
383 citations
TL;DR: Based on the working mechanisms, a systematic literature review is logically presented to reveal that the thermo- and chemo- responsive shape memory effects (SMEs) are not the special phenomena of some particular polymers, but intrinsic features of most polymers as discussed by the authors.
Abstract: Based on the working mechanisms, a systematic literature review is logically presented to reveal that the thermo- and chemo- responsive shape memory effects (SMEs) are not the special phenomena of some particular polymers, but intrinsic features of most polymers (if not all). Subsequently, referring to the most recent experimental results and their theoretical origins, we reveal the fundamentals on the optimization of the SME in polymers and the approaches to design/synthesize polymeric materials with tailored features.
258 citations