Modeling and Characterization of Cyclic Shape Memory Behaviors of the Binary Ni 49.9 Ti 50.1 Material System
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JMEPEG DOI: 10.1007/s11665-017-2721-8
Modeling and Characterization of Cyclic Shape Memory Behaviors of the Binary Ni49.9Ti50.1 Material System A.F. Saleeb, S.H. Natsheh, J.S. Owusu-Danquah, and B. Dhakal (Submitted May 23, 2016; in revised form April 6, 2017) In this work, we address two of the main challenges encountered in constitutive modeling of the thermomechanical behaviors of actuation-based shape memory alloys. Firstly, the complexity of behavior under cyclic thermomechanical loading is properly handled, particularly with regard to assessing the long-term dimensional stability. Secondly, we consider the marked differences in behavior distinguishing virginversus-trained SMA material. To this end, we utilize a set of experimental data comprehensive in scope to cover all the anticipated operational conditions for one and same SMA alloy, having a specific chemical composition with fixed heat treatment. More specifically, this includes twenty-four different tests from the recent SMA experimental literature for the Ni49.9Ti50.1 material having austenite finish temperature above 100 °C. Under all the different conditions investigated, the model results were found to be in very good agreement with the experimental measurements. Keywords
aerospace, intermetallic, modeling and simulation, shape memory alloys, two-way shape memory
microstructure of the alloy, which make the material more stable during the targeted no-load two-way shape memory behavior.
1.2 Review of Previous Work
1. Introduction 1.1 General Increasing availability of different types of shape memory alloys (SMAs) has intensified the effort toward the design and development of many engineering devices providing unique, useful functions under a wide range of mechanical and thermal conditions. In particular, the shape memory effect (SME), which defines the ability of an SMA material to remember a set shape, is typically exploited in the design of actuators and sensors. Depending on the thermal and mechanical loading procedure, the SME behavior can be categorized into two main types; i.e., the one-way shape memory effect (OWSME) and the two-way shape memory effect (TWSME) (Ref 1-4). Although the one-way shape memory behavior is elemental to most SMAs, the two-way shape memory effect is not, rather requiring specialized heat treatments and/or thermomechanical training for this phenomenon to be induced in the alloy (Ref 5). Despite the fact that no direct physical mechanism is yet attributed to the occurrence of TWSME in the SMA literature, generation of internal stress fields (Ref 6) at both the austenitic and martensitic transformation phases is considered to be a major agent for this phenomenon (Ref 7). This is usually attained through either one-time martensitic loadunload deformation (Ref 8) or several isobaric thermomechanical cycling between temperatures above the austenite finish, Af, and below the martensite finish, Mf (Ref 9, 10). These training methods introduce defects/dislocations in the A.F. Saleeb, S.H. Natsheh, J.S. Owusu-Danquah, and B. Dhakal,
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