Thermomechanical responses of nonlinear torsional vibration with NiTi shape memory alloy – Alternative stable states and their jumps

Abstract

The dynamic response of nonlinear torsional vibration with phase transformable NiTi Shape Memory Alloy (SMA) wire is investigated by experiment in this paper. The thermomechanical responses of NiTi wire as a softening nonlinear damping spring in the torsional vibration system are measured by synchronized acquisition of the rotational angle and temperature under external excitation. Frequency Response Curves (FRCs) at fixed excitation amplitude and Amplitude Response Curves (ARCs) at fixed frequency are obtained in the frequency and amplitude domains respectively. It is found that, as the deformation of NiTi wire goes into the softening nonlinear phase transition region, the smooth and stable dynamic responses along one branch of FRC or ARC will gradually enter into metastable region and eventually become unstable and drastically switch to a new contrasting alternative stable state along the other branch. The jump phenomenon between the alternative stable states on the lower and upper branches of the FRC or ARC and the hysteresis between the jump-up and jump-down are identified in experiments. In addition, the effects of internal and external disturbance (both magnitude and direction) on triggering the jumps between the alternative stable states along the two metastable branches are examined in the time domain. The stability of the nonlinear dynamic response is analyzed by the Duffing oscillator model and interpreted via the stability landscape. For the first time, we directly reveal the alternative stable states and jump phenomena of thermomechanical responses by experiments in the frequency, amplitude and time domains. The results not only showed the important roles of phase transition nonlinearity in bringing multiple equilibrium states and their fast switches, but also provided a solid experimental base for the identification of metastable regions as well as further management of the undesired dynamic responses of vibration system where NiTi is used as a nonlinear damping spring.

Thermomechanical and electrical response of a superelastic NiTi shape memory alloy cable

“…A typical NiTi SMA is composed of 49% to 57% of nickel and balanced with titanium (Barbarino et al, 2014). The distinctive properties of SMAs have prompted their use in various engineering fields such as biomedical (Brandal et al, 2015; Gu et al, 2017; Kaczmarek and Kurtyka, 2017; Tao et al, 2017; Yu et al, 2016; Zeng et al, 2020) and mechanical engineering (Mani and Senthilkumar, 2015; Xia and Sun, 2017).…”

Grain size effects on stability of nonlinear vibration with nanocrystalline NiTi shape memory alloy

“…In the following, we will briefly outline the theoretical modelling procedures to interpret the above experimental observations. Thermomechanical coupling effects of NiTi SMA are decoupled by separately considering the mechanical response and thermal response [6,7]. Therefore, mechanical response can be obtained through an effective Duffing oscillation model consisting of a cubic nonlinear softening spring (…”

“…Replacing b by q and a (b q a q p = + = + A ft sin 2 ), we have The steady-state response is obtained through the method of multiple scales heat analysis (see [6,7] for more details) is performed to establish the relationship between temperature oscillation (DT ) and rotation ( q D ) of the NiTi bar, and c , eq thermal response of the nonlinear dynamic system further involves specific latent heat (l 0 ) of the nanocrystalline material.…”

“…Average temperature of the NiTi bar (T ) was measured by an infrared camera (SC7700M from FLIR, USA) after matt black painted (TS-6 from Tamiya, Japan) to enhance the thermal emissivity. Peak-to-valley magnitudes of rotational angle and average temperature ( q D and DT ) in the steady-state oscillation were quantified as mechanical response and thermal response of the torsional vibration system (see [7] for more details).…”

“…When NiTi SMA is used as a nonlinear damping component, such instability manifests as the jump phenomena of thermomechanical responses from one branch of solution to the alternative branch in the frequency and amplitude domains as shown in figure 1(c) [6,7]. When deformation of NiTi SMA is in softening nonlinear phase transition stage, the smooth and stable dynamic response along one branch of frequency response curve (FRC) or amplitude response curve (ARC) will gradually go into a metastable region and eventually become unstable and drastically switch to a contrasting alternative stable state along the other branch of FRC or ARC.…”