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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.

2

Analiza wytężenia kompozytowych elementów rurociągów

Hufenbach W., Kroll L., Gude M., Bohm R., Czulak A.

Kompozyty

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2006

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R. 6, nr 4

3-8

PL

Kompozyty wzmocnione zarówno włóknem szklanym, jak i węglowym charakteryzują się lepszymi parametrami użytkowymi w stosunku do klasycznych materiałów w konstrukcjach lekkich, a w szczególności w przemyśle lotniczym, samochodowym i chemicznym. W tym ostatnim, dzięki doskonałym własnościom wytrzymałościowym i odpowiedniej odporności na działanie związków chemicznych, obok elementów rur stalowych często wykorzystuje się elementy warstwowo wzmocnionych rur hybrydowych. Ich struktura nośna składa się ze zbrojonych włóknami szklanymi tworzyw termo-i chemoutwardzalnych. Tego rodzaju instalacje z tworzywa sztucznego wzmocnionego włóknem szklanym służą przede wszystkim do transportu związków chemicznych, odprowadzania ścieków przemysłowych, doprowadzania wody przemysłowej, ale także wykorzystuje się je jako rury kanalizacyjne oraz elementy odciągów powietrza lub gazów technicznych. Dodatkowo, do specjalnych zastosowań można użyć jako osnowy różnorodnych reaktywnych, termo- i chemoutwardzalnych żywic, takich jak nienasyconej żywicy poliestrowej lub winylowej posiadającej dobrą trwałość chemiczną. W pracy przedstawiono analizę wytężeniową rur kompozytowych, jak również zoptymalizowano ułożenie włókien przy użyciu metody elementów skończonych w zaawansowanych programach graficznych.

EN

Fiber reinforced composites offer a - not yet utilized - lightweight potential for innovative lightweight applications in aircraft, automotive and chemical industry. Especially in the latter case, fibre reinforced polymers (FRP) are predestined for the application in hybrid tubes of piping systems, due to the splendid strength properties of FRP and their adequate resistance against chemical compounds. The tube's carrying structure generally consists of glass fiber reinforced heat-hardening or chemical hardening matrices, whereas a polymer liner often protects the carrying structures against extremely aggressive fluids and gases. In special applications, additionally various reactive, thermo hardening and chemical hardening resins, such as non-saturated polyester or vinyl resins, can be used as a matrix which show a good chemical durability. Such piping systems made of fiber reinforced composites are used to transport chemical compounds, drain the liquid industrial wastes and convey industrial water. Moreover, the FRP-pipings are used as sewage pipes, elements of air draft and technical gases. This paper focuses the structural design of FRP-tubes regarding the optimum composite lay-up including a strength analysis of composite tubes with use of finite element methods using the program systems I-DEAS and ANSYS.

3

Novel tests and inspection methods for textile reinforced composite tubes

Hufenbach W., Kroll L., Gude M., Czulak A., Böhm R., Danczak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 14, nr 1-2

70--74

EN

Purpose: This paper describes innovative lightweight applications of fiber and textile reinforced polymers in aircraft, automotive and chemical industry. Design/methodology/approach: This paper deals with modern test methods of braided composite tube specimens as basic elements of modern composites. The tubes subjected to strength tests under superposed compressive, tensile and internal pressure loadings, and tested by the acoustic emission method for damage detection. Findings: For the quality assessment and here, especially for the verification of fibre orientations after manufacture, the X-ray method is an advantageous inspection method. For the identification of fracture modes, after uni- and biaxial mechanical test under tensile, compressive and torque loads as well under inner pressure loading the computer tomography CT is used. The acoustic emission to assess for damage detection in braided composite pipes, and mechanical loading. Moreover, from the applied techniques the information concerned quality of a manufactured specimen, damage propagation and determination the types of damages can be obtained. Research limitations/implications: Those three methods assure very good and promising results having one limitation in case of volume of a tested sample, e.g in the CT device, an allowable diameter of an investigated tubular specimen amounts to 150mm. Practical implications: Use of the methods resulted in improved efficiency of test process and analysis of GFRP tubular specimens. Originality/value: The paper describes the new implicated test and inspection methods for textile reinforced composite tubes.