Shape memory alloys as an effective tool to damp oscillations

Abstract

The SMA was studied for their macroscopic application in damping for civil engineering. The study is a synthesis and includes an outline of the models required for the SMA simulation and some case studies using the finite element analysis methods. This work is an overview that focuses in the mitigation of the oscillations in structures induced by earthquakes, and for a reduction of the oscillations amplitude in stayed cables under the action of rain, wind or traffic. The analysis needs the required conditions for each application determining the working conditions. The study includes the number of working cycles, the temperature effects and the cooling actions and, for instance, the action of the cycling frequency. The main target relates the appropriateness of the SMA for each purpose, and the suitability of the SMA device is always experimentally guaranteed. Furthermore, the applicability of the obtained results for SMA and the practical behavior of the SMA dampers were studied in international facilities. The paper includes appropriate suggestions for a correct preparation of the SMA dampers. This work outlines the effects of stress and temperature aging in NiTi, describes the particular structural effects between 18R and 6R, introduces a first attempt in the dynamic properties of the CuAlBe single crystals and summarizes some recent suggestions for damping using SMA.Keywords Shape memory alloys Á Martensitic transformation Á NiTi Á CuAlBe Á Damping Á Fatigue Part oneThe martensitic transformation (MT) is the origin of the unique properties of shape memory alloys (SMA) [1,2]. MT is a first-order phase transition between metastable phases with hysteresis. The transformation takes place with small displacements of the atoms and without any change in the positions of the neighboring atoms: Atomic order is conserved in the transformation. The transformation can be induced by temperature or by external forces, such as traction or compression. In temperature-induced transformations, M s (martensite start) denotes the starting temperature. The M f (martensite finish) temperature determines the end of the transformation, and A s and A f denote the austenite start and the austenite finish temperatures, respectively. This part was devoted to general contents and properties of the SMA appropriate for damping of oscillations. In particular, reduction of oscillations appeared in civil engineering structures.

Heat transfer analysis of fast response sensor for internal combustion engine based on Coiflet wavelet finite element method

“…And the boundary conditions of heat transfer analysis for fast response temperature sensor are listed as follows [15]:…”

Functional fatigue recovery of superelastic cycled NiTi wires based on near 100 °C aging treatments

“…Alternatively, at constant maximum strain, a decrease of stress to transform is observed [6]. From the pioneering work of [20] it has been reported the evolution of transformation curves with pseudoelastic cycling, and also with thermal cycles in [21], the evolution was associated to an increase of dislocation density [22][23].…”

“…The properties of Shape Memory Alloys in pseudoelastic state give high mechanical damping, and NiTi wires have been proposed as dampers in civil engineering [3][4][5][6]. For this kind of SMA applications, high reliability is needed [7].…”

Thermally modulated shape memory alloy friction pendulum (tmSMA-FP) for substantial near-fault earthquake structure protection

“…Finally, SMAs have demonstrated superior control efficiency in protecting highway bridges and buildings from near‐fault earthquakes . Several studies by Torra and coresearchers demonstrate the application of SMA dampers (such as NiTi and CuAlBe) for vibration control in civil engineering structures and stayed cables in bridges . Those studies demonstrate that SMA dampers can be designed such that they (a) provide high and tunable (through temperature) energy dissipation capacity, (b) are capable of recovering large residual strains at elevated temperature, and (c) have a reasonably high fatigue.…”