Strain rate dependent formulation of the latent heat evolution of superelastic shape memory alloy wires incorporated in multistory frame structures

Abstract

Due to their unique hysteretic energy dissipation capacity, shape memory alloy (SMA) wires are particularly interesting for the development of new-type of intelligent vibration control systems for structures. However, in structural control, most of the vibrations occur in high strain rate regimes, which interfere the release of self-generated heat and thus influence the hysteretic dissipation. This paper proposes a strain rate dependent formulation of the latent heat evolution and aims to improve the accuracy of existing macroscopic modeling approaches developed for SMA wires particularly for the dynamic load cases. The proposed formulation is determined phenomenologically and implemented in a continuum thermomechanical framework based constitutive SMA wire model without impairing the simplicity and robustness of the solution process. The proposed formulation is validated by cyclic tensile tests conducted on SMA wires. Results show that the calculations using the formulation can predict the wire response more accurately than the strain rate independent formulation. For the simulation of multistory frame structures incorporating multiple SMA wires, the governing equations are driven. Shaking table tests are conducted on a 3-story frame structure under harmonic and seismic excitation. The responses of the structure are successfully replicated using the strain rate dependent latent heat formulation.

Parameter Identification and Modeling of Superelastic Shape Memory Alloy Wires Subjected to Dynamic Loads

“…Particularly for the dynamic response modeling, these parameters are hard to identify as they are interacting with each other. For example, as can be seen in Equations (5,6) and (10), there is a direct relation between the speed parameters, critical stresses, and entropy difference, so that these parameters have to be adjusted with respect to each other.…”

“…As a consequence, many one-dimensional thermodynamically-coupled constitutive models have been proposed, such as in [3,4]. Various improvements to these models have also been proposed, Niklas Lenzen, Sven Klinkel and Okyay Altay such as in [5,6]. A detailed review of constitutive models and modeling techniques for SMAs can be found in [7], and references therein.…”

Neural Network Parameter Identification Based Constitutive Modeling of Superelastic Shape Memory Alloys

“…The proposed identification approach is assembled by a physics based forward model and a data based reverse model. The forward model is an improved version of the macroscopic uniaxial constitutive model of Zhu and Zhang [1,2]. Based on the free energy and heat equations…”

“…From the identified parameters of each loading pattern, a final set of parameters is chosen. To test the performance of the ANN, experimental stress response data is used, which is generated by cyclic tensile tests [2].…”

Machine Learning Enhanced Dynamic Response Modelling of Superelastic Shape Memory Alloy Wires

“…Since then, several one-dimensional thermomechanically coupled constitutive models were designed, such as in [ 11 , 12 ]. Improved versions of these models are also proposed in [ 13 , 14 ]. For a detailed review on other modelling techniques, we refer the interested readers also to [ 15 ] and references therein.…”