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Article

Critical Frequency of Self-Heating in a Superelastic Ni-Ti Belleville Spring: Experimental Characterization and Numerical Simulation

Multidisciplinary Laboratory of Active Materials and Structures (LaMMEA), Department of Mechanical Engineering, Federal University of Campina Grande, Campina Grande 58429-140, Brazil
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Academic Editors: Susana Catarino and Óscar Samuel Novais Carvalho
Sensors 2021, 21(21), 7140; https://doi.org/10.3390/s21217140
Received: 22 July 2021 / Revised: 13 September 2021 / Accepted: 13 September 2021 / Published: 27 October 2021
The mechanical loading frequency affects the functional properties of shape memory alloys (SMA). Thus, it is crucial to study its effect for the successful use of these materials in dynamic applications. Based on the superelastic cyclic behavior, this work presents an experimental methodology for the determination of the critical frequency of the self-heating of a NiTi Belleville conical spring. For this, cyclic compressive tests were carried out using a universal testing machine with loading frequencies ranging from 0.5 Hz to 10 Hz. The temperature variation during the cyclic tests was monitored using a micro thermocouple glued to the NiTi Belleville spring. Numerical simulations of the spring under quasi-static loadings were performed to assist the analysis. From the experimental methodology applied to the Belleville spring, a self-heating frequency of 1.7 Hz was identified. The self-heating is caused by the latent heat accumulation generated by successive cycles of stress-induced phase transformation in the material. At 2.0 Hz, an increase of 1.2 °C in the average temperature of the SMA device was verified between 1st and 128th superelastic cycles. At 10 Hz, the average temperature increase reached 7.9 °C and caused a 10% increase in the stiffness and 25% decrease in the viscous damping factor. Finally, predicted results of the force as a function of the loading frequency were obtained. View Full-Text
Keywords: shape memory alloys; superelasticity; Ni-Ti Belleville spring; self-heating frequency; dynamic loading shape memory alloys; superelasticity; Ni-Ti Belleville spring; self-heating frequency; dynamic loading
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MDPI and ACS Style

de Souza, E.F.; da Silva, P.C.S.; Grassi, E.N.D.; de Araújo, C.J.; de Lima, A.G.B. Critical Frequency of Self-Heating in a Superelastic Ni-Ti Belleville Spring: Experimental Characterization and Numerical Simulation. Sensors 2021, 21, 7140. https://doi.org/10.3390/s21217140

AMA Style

de Souza EF, da Silva PCS, Grassi END, de Araújo CJ, de Lima AGB. Critical Frequency of Self-Heating in a Superelastic Ni-Ti Belleville Spring: Experimental Characterization and Numerical Simulation. Sensors. 2021; 21(21):7140. https://doi.org/10.3390/s21217140

Chicago/Turabian Style

de Souza, Emmanuel F., Paulo C.S. da Silva, Estephanie N.D. Grassi, Carlos J. de Araújo, and Antonio G.B. de Lima 2021. "Critical Frequency of Self-Heating in a Superelastic Ni-Ti Belleville Spring: Experimental Characterization and Numerical Simulation" Sensors 21, no. 21: 7140. https://doi.org/10.3390/s21217140

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