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Critical Frequency of Self-Heating in a Superelastic Ni-Ti Belleville Spring: Experimental Characterization and
Emmanuel Ferreira de Souza1, Paulo César Sales da Silva1, Estephanie Nobre Dantas Grassi1
1Multidisciplinary Laboratory of Active Materials and Structures (LaMMEA), Department of Mechanical Engineering, Federal University of Campina Grande, Campina Grande 58429-140, Brazil.
Sensors (Basel, Switzerland)
|November 13, 2021
Summary
Loading frequency significantly impacts shape memory alloy (SMA) properties. This study determined the critical self-heating frequency for NiTi Belleville springs, crucial for dynamic applications.
Area of Science:
- Materials Science
- Mechanical Engineering
- Thermodynamics
Background:
- Shape memory alloys (SMAs) exhibit functional property changes with mechanical loading frequency.
- Understanding these effects is vital for SMAs in dynamic applications.
Purpose of the Study:
- To establish an experimental method for determining the critical self-heating frequency of a NiTi Belleville conical spring.
- To analyze the impact of loading frequency on SMA spring behavior.
Main Methods:
- Cyclic compressive tests on a NiTi Belleville spring using a universal testing machine.
- Loading frequencies ranged from 0.5 Hz to 10 Hz.
- Temperature monitoring via micro-thermocouple and numerical simulations.
Main Results:
- A critical self-heating frequency of 1.7 Hz was identified for the NiTi Belleville spring.
- Self-heating results from latent heat accumulation during stress-induced phase transformations.
- At 10 Hz, temperature increased by 7.9 °C, leading to a 10% stiffness increase and 25% damping decrease.
Conclusions:
- The experimental methodology effectively determines the critical self-heating frequency in SMA springs.
- Loading frequency significantly alters SMA spring performance, affecting stiffness and damping.
- Results provide crucial data for designing SMA devices for dynamic environments.
Keywords:
Ni-Ti Belleville springdynamic loadingself-heating frequencyshape memory alloyssuperelasticityMore Related Videos
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