FEM Simulation of Dissipation and Damping in Shape Memory Alloys

Yugal Agrawal

WW8, FAU

10. July 2019, 17.00
WW8, Room 2.018, Dr.-Mack-Str. 77, Fürth

Shape Memory Alloys (SMAs) are a unique class of metallic alloys that can change their original crystallographic structure when subjected to external stress and temperature and have the property of recovering their apparent shape after deformation. This work investigates the use of shape memory alloys (SMAs) for dissipation and damping of mechanical systems using finite element simulation and is divided into two parts.

The first part is the numerical implementation and validation of a rate independent constitutive model for polycrystalline shape memory alloys as proposed by Lagoudas and Boyd, using finite elements. The thermodynamically consistent constitutive model accounts for thermomechanical coupling and captures the stress/temperature induced austenite to martensite phase transformation. The analysis is performed under different strain rates to simulate situations ranging from quasi-static to quasi-adiabatic conditions. The effects of strain rates, as well as temperature, on the hysteresis are investigated and verified using experimental data.

The second part presents a numerical study of the dynamic analysis of the free and forced vibration of a miniature stripe of pseudoelastic SMA and evaluating this novel miniature stripe for damping applications. The device, a mass-spring system connected to the SMA stripe, is subjected to a series of pulse/sinusoidal excitation forces simulating free/forced vibration. The effects of excitation load and pre-straining are investigated. It is shown that the damping energy has a direct relation to the pre-strain and has maximum values at optimum prestrain, for a given excitation load.