The singular properties of Shape Memory Alloys (SMA), which are due to a thermoelastic martensitic transformation, made them attractive for use as actuators or as dampers. The dampers could use preferably the stronger effect of the pseudoelastic window and the hysteresis on transforming- retransforming, but also other processes that are available, as damping in martensite phase (rubber-like effect). The application of SMA to practical uses need well established performance and life. The reliable application in some areas, as dampers in Civil Engineering, needs guaranteed properties. The requirements have to be clearly set to look for applicability of specific alloys, conditioning treatments, and devices. In Civil Engineering, the damping of earthquake effects might need some hundreds or one thousand of working cycles, while the damping of wind-induced vibrations would need to support many millions of cycles without failure to be useful. The required number of cycles will then limit the maximum design stresses and strains on the material to perform without failure, and these will directly influence the dimensioning of the devices. This work deals with some results on fatigue of NiTi pseudoelastic wires, and points the possibility to apply NiTi as damper material. Fatigue has to be studied for concrete applications, with the correct samples.

NiTi Wires for Dampers and Actuators: Fatigue

CASCIATI, FABIO;CASCIATI, SARA
2012-01-01

Abstract

The singular properties of Shape Memory Alloys (SMA), which are due to a thermoelastic martensitic transformation, made them attractive for use as actuators or as dampers. The dampers could use preferably the stronger effect of the pseudoelastic window and the hysteresis on transforming- retransforming, but also other processes that are available, as damping in martensite phase (rubber-like effect). The application of SMA to practical uses need well established performance and life. The reliable application in some areas, as dampers in Civil Engineering, needs guaranteed properties. The requirements have to be clearly set to look for applicability of specific alloys, conditioning treatments, and devices. In Civil Engineering, the damping of earthquake effects might need some hundreds or one thousand of working cycles, while the damping of wind-induced vibrations would need to support many millions of cycles without failure to be useful. The required number of cycles will then limit the maximum design stresses and strains on the material to perform without failure, and these will directly influence the dimensioning of the devices. This work deals with some results on fatigue of NiTi pseudoelastic wires, and points the possibility to apply NiTi as damper material. Fatigue has to be studied for concrete applications, with the correct samples.
2012
9788895023137
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/442376
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