Loading frequency and temperature-dependent damping capacity of NiTiHfPd shape memory alloy. (November 2020)

• Record Type: Journal Article
• Authors: Toker, Guher P.; Saedi, Soheil; Acar, Emre; Ozbulut, Osman E.; Karaca, Haluk E.
• Is Part Of: Mechanics of materials. Volume 150(2020)
• Publication Date: 2020-11
• Subjects: Shape memory alloys -- Damping capacity -- Stress/mechanical hysteresis -- Latent heat -- Loading frequency/rate effect; Strength of materials -- Periodicals; Mechanics, Applied -- Periodicals; Résistance des matériaux -- Périodiques; Mécanique appliquée -- Périodiques; Mechanics, Applied; Strength of materials; Periodicals; Electronic journals; 620.11
• DOI: 10.1016/j.mechmat.2020.103565
• Languages: English
• ISSNs: 0167-6636

Abstract

Abstract: Superelastic shape memory alloys with ultra-high-strength, large mechanical hysteresis, and the ability to recover large deformations are promising materials for damping applications. In this study, the superelastic response and damping capacity of quaternary Ni45 ·3 Ti39 .7 Hf10 Pd5 polycrystalline alloys are investigated in terms of temperature and loading frequency dependency. It is shown that this alloy can show fully recoverable superelastic behavior with strain amplitude of 6–7% from −40 °C to 80 °C after heat treatments. The damping capacity of 550°C-3h aged alloy at 20 °C was 22.5 J/cm 3 for quasi-static loading which decreased to 12.5 J/cm 3 under 1 Hz loading frequency. At the high temperature of 80 °C the damping capacity was determined 9.2 J/cm 3 under quasi-static loading and 4 J/cm 3 under 1 Hz loading frequency. The decrease in damping capacity with loading frequency and temperature is linked to: the changes in local temperature of the specimen which significantly increases critical stress for reverse transformation while not affecting the critical stress for forward transformation, improved compatibility of transforming phases, and decrease in the contribution of superelastic strain to the total recovered strain. Highlights: 7% full deformation recovery was achieved within a wide temperature span and under high loading frequencies. Unlike the forward transformation, the critical stress for reverse transformation is highly sensitive to the loading rate. The energy dissipation of the alloy is strongly affected by both the temperature and loading rate. The dependency of the reverse transformation to loading frequency is reduced at higher operating temperatures.