Characterizations of SMA springs for seismic applications

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Characterizations of SMA springs for seismic applications

 

Author: He, Yifan
Title: Characterizations of SMA springs for seismic applications
Degree: M.Sc.
Year: 2014
Subject: Shape memory alloys.
Shape memory effect.
Springs (Mechanism)
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Construction and Environment
Pages: vi, 59 leaves : illustrations ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2759221
URI: http://theses.lib.polyu.edu.hk/handle/200/7609
Abstract: In this study, the mechanical behavior of superelastic shape memory alloy(SMA) helical springs under axial force is the mainly investigated. The goal is to evaluate the SMA-based device response and to exploit the superelastic behavior, the main target being material and geometrical response non-linearity. The research is made of two parts, an experimental process and a numerical analysis. Experimental tests have been conducted on shape memory alloy helical springs in tension and compression for several different materials, wire diameters and spring geometrical dimensions. Shape memory alloys have a lot of potential in many applications because of its special unique effects, for example, super-elastic effect, it can allow the SMAs achieve large hysteretic deformation without undeformed strain, so SMAs have potential for application in earthquake engineering passive damping devices. Tested specimens experience an appropriate elongation that test machine can provide and they are larger than the original spring axis length. The test results are not symmetric and under compression they almost remain in their elastic range and affected by buckling instability. Nevertheless, the experimental results show a very good super-elastic behavior with no damage of the spring and with inappreciable residual displacements. And the comparison between the spring and the single wire shows that the spring have greater mechanical property.

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