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Polyurethane shape memory polymer: structure characterization and estimation of energy storage and dissipation during the tension process

Staszczak Maria, Gradys Arkadiusz, Golasiński Karol, Pieczyska Elżbieta A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 6

art. no. e147343

EN

Shape memory polymers (SMP) are new multifunctional materials raising increasing interest in various functional applications. Among them, polyurethane shape memory polymers (PU-SMP) are particularly attractive due to their combination of shape memory, high strength and biocompatible properties. Developing new applications for PU-SMP requires comprehensive research on their characteristics. This work involved investigating the structure and mechanical behavior as well as characterizing the energy storage and dissipation of a thermoplastic PU-SMP with a glass transition temperature (Tg) of 25_C during tensile loading-unloading. The process of energy storage and dissipation in the PU-SMP was investigated based on the stress-strain curves recorded by a quasi-static testing machine and the temperature changes, accompanying the deformation process, obtained by using a fast and sensitive infrared camera. The results showed that the thermomechanical behavior of the examined PU-SMP depends significantly on the strain rate. At a higher strain rate, there are higher stress and related temperature changes, which lead to greater energy dissipation. However, the energy storage values estimated during the deformation process turned out to be not significant, indicating that the work supplied to the PU-SMP structure during loading is mainly converted into heat. It should also be noted that the structural investigation revealed no crystalline phase in the investigated PU-SMP.

2

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.

3

Possibility of the Use of Different Types of Materials in Passive Ventilation Systems of Munitions

Wiśniewski A.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2016

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Vol. 7, Nr 3 (25)

21--34

EN

The paper presents different types of insensitive munition used in military equipment, especially in western countries. Tests of this munition, their parameters, e.g. fast and slow heating, bullet, fragment and shaped charge jet impact and sympathetic reaction are described. The characteristics of shape-memory materials like alloys and polymers are presented. Behaviour of shape-memory alloy is explained by example of TiNi al-loys during mechanical or thermal loading, and martensitic transformation into austen-ite during unloading. Material parameters of the TiNi alloys, their testing and mathematical equations are shown. Venting systems used in the explosive reactive armour cassettes are presented. Different examples of materials, including shapememory materials in munition, are demonstrated.

4

Investigation of thermal effects accompanying tensile deformation of Shape Memory Polymer PU-SMP

Pieczyska E. A., Staszczak M, Maj M., Tobushi H., Hayashi S.

Measurement Automation Monitoring

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2015

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Vol. 61, No. 6

203--205

EN

Experimental results of effects of thermomechanical couplings occurring in shape memory polymer subjected to tension are presented. Stress-strain curves were recorded by testing machine, while their related temperature changes were measured with infrared camera. The mechanical and thermal characteristics were used to investigate the polymer properties. Three various stages were distinguished during the deformation process. The first, elastic, is accompanied by a drop in the specimen temperature; the second, plastic, is associated with change of the material structure and the temperature increase; the third stage, related to the specimen rupture and damage mechanisms, is accompanied by the significant increase in temperature.

5

Novel shape memory actuators

Tobushi H., Miyamoto K., Nishimura Y., Mitsui K.

Journal of Theoretical and Applied Mechanics

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2011

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Vol. 49 nr 3

927-943

EN

In order to develop novel shape memory actuators, the torsional deformation of a shape memory alloy (SMA) tape and the actuator models driven by the tape were investigated. The shape memory composite (SMC) belt composed of SMA tapes and a shape memory polymer (SMP) was fabricated, and the three-way bending characteristics were also investigated. The results obtained can be summarized as follows. In the SMA tape subjected to torsion, the martensitic transformation appears along the edge of the tape due to elongation of the edge of the tape and grows to the central part. The fatigue life in both the pulsating torsion and alternating torsion is expressed by a unified relationship of the dissipated work in each cycle. Based on the two-way motion of an opening and closing door model and a solar-powered active blind model driven by two kinds of SMA tape, it is confirmed that the two-way rotary driving actuator with a small and simple mechanism can be developed by using torsion of the SMA-tape. The SMC belt laminated with the SMP tape and SMA tapes was fabricated. The three-way bending movement of the SMC belt was achieved during heating and cooling based on the charac- teristics of the SMA tapes and the SMP tape. The active SMC actuator with various three-dimentional movements can be developed by applying the three-way properties of the SMC.

PL

W pracy zajęto się aktuatorami nowego typu, w których zastosowano stop z pamięcią kształtu (SMA) w postaci skręcającej się taśmy SMA wywołującej ruch aktuatora. Opracowano kompozytowy pas (SMC) z taśm SMA oraz polimeru wykazującego efekt pamięci kształtu (SMP) oraz zbadano charakterystyki takiego kompozytu przy zginaniu trójosiowym. Rezultaty badań pokazały, że taśma SMA poddana skręcaniu doznaje przemiany martenzytycznej wzdłuż krawędzi z powodu jej wydłużania, która stopniowo przechodzi do środkowej części taśmy. Problem wytrzymałości zmęczeniowej taśmy obciążonej jednokierunkowym i naprzemiennym skręcaniem opisano ujednoliconym wyrażeniem określającym pracę dyssypacji na każdy cykl obciążenia. Zbadano model aktuatora dwustronnego działania do otwierania i zamykania drzwi oraz do sterowania przesłony zasilanej energią słoneczną. Potwierdzono skuteczność torsyjnego aktuatora SMA przy utrzymaniu prostoty konstrukcji takiego mechanizmu. Przeanalizowano przestrzenny ruch kompozytowego pasa SMC indukowanego ogrzewaniem i chłodzeniem w zależności od charakterystyk taśm SMA i SMP. Pokazano, że dzięki właściwościom kompozytu SMC różnych w trzech kierunkach, uzyskanie zdolności ruchowej aktuatora w przestrzeni (3D) jest możliwe.

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Three-way actuation of shape memory composite

Tobushi H., Hayashi S., Pieczyska E., Date K., Nishimura Y.

Archives of Mechanics

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2011

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Vol. 63, nr 5-6

443-443

EN

The SMC belt composed of two kinds of SMAs with different phase transformation temperatures and SMP, was fabricated and the three-way (reciprocating) movement and recovery force in bending actuation were investigated. The results obtained can be summarized as follows. 1) The three-way bending movement was achived during heating and cooling, based on the characteristics of the SMA tapes and the SMP tape. 2) The recovery force decreased at first and increased thereafter during heating and decreased during cooling. The recovery force was roughly estimated by the proposed model. 3) The development and application of multi-functional SMCs with simple structure for three-dimensional actuators are highly expected.

7

Improving the mechanical properties of braided shape memory polymer stents by heat setting

Schreiber F., Schuster P., Borinski M., Vogt F., Blindt R., Gries T.

Autex Research Journal

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2010

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Vol. 10, no. 3

73--76

EN

The aging population is one of the biggest challenges of the 21st century and so is the subsequent increase in patients with cardiovascular diseases. The state-of-the-art treatment for cardiovascular stenosis is an angioplasty in combination with stenting of the affected artery. Stents can be either laser cut out of a tube or an interwoven such as a braided structure. Furthermore, there are two groups of stents regarding their expansion behaviours: balloon expandable and self-expandable. Within this paper, a new approach to braiding stent-like structures out of a novel shape memory polymer fibre will be discussed. Furthermore, the heat treatment of the stent structure will be investigated to improve its characteristics such as radial stiffness.