Únavové vlastnosti slitin s tvarovou pamětí s ohledem na jejich využití v medicíně
Title Alternative:Fatigue Properties of Shape Memory Alloys with Regard to Their Use in Medicine
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Date
2015
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Publisher
Technická Univerzita v Liberci
Abstract
This work deals with characterization of Nickel-Titanium shape memory alloy which is used for production of cardiovascular stents. Material tests such as Differential Scanning Calorimetry and tensile tests carried out under different values of temperature allowed for precise description of material's pseudoelastic effect. Moreover, fatigue tests of the alloy were done under two different values of temperature and its corresponding S-N curves were constructed. On the basis of experimental data, full range of loads which are imposed on stent during its life are studied using finite element method. In this part, loading a stent into catheter and its subsequent deployment in blood vessel was simulated. Following simulation of pressure pulse offered data about cyclic loading to which the stent is exposed when implanted into an artery. Thanks to previous simulation and known S-N curve of the material, durability analysis of the stent was done with use of nominal stress approach. In last part of the work, a device dedicated to cyclic testing of the whole stent-graft structure is constructed. Concept of the machine, together with corresponding calculations are shown. Outcome of this work is a fully operational machine at which eight stent-grafts can be tested at the same time. Pressure characteristics which acts inside mock arteries was experimentally verified to be similar to conditions in human body.
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CD-R s elektronickou verzí práce.