A theoretical model for functionally graded shape memory alloy cylinders subjected to internal pressure
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Shilong Hu Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin 300300, China
Wei Zhanga) College of Aeronautical Engineering, Civil Aviation University of China, Tianjin 300300, China; and Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin 300300, China
Rui Zhou College of Aeronautical Engineering, Civil Aviation University of China, Tianjin 300300, China
Yanan Zhang Airport College, Civil Aviation University of China, Tianjin 300300, China
Yuping Zhu Key Laboratory of Seismic Observation and Geophysical Imaging, Institute of Geophysics, China Earthquake Administration, Beijing 100081, China (Received 18 September 2016; accepted 18 November 2016)
A theoretical model for the Functionally Graded Shape Memory Alloy (FG-SMA) cylinders subjected to internal pressure is investigated. The gradient properties in this work are embodied in the Young’s modulus and Poisson’s ratio gradient through the thickness of the cylinder. The critical transformation stresses and maximum formation strain are all assumed to be constant. Combining the elasticity and exponential function of the Young’s modulus and Poisson’s ratio with the different gradient parameters, the elastic stress distributions and displacement distributions for the FG-SMA cylinder under the internal pressure are obtained, respectively. To get the theoretical solution, the Tresca yield function and the ideal elastic–plastic constitutive model are selected for the shape memory alloy to illustrate the phase transformation. The relationships between the internal pressure and total strain at the internal radius with different gradient parameters are then given, and the results show that the total strains are greatly influenced by the different parameters.
I. INTRODUCTION
As new kinds of the functional materials, due to the gradual varying properties or the microstructure, the Functionally Graded Materials (FGMs) have been explored for the continuously increasing engineering applications including the structure optimization, fission and fusion reactors, thermally resistant materials, the aerospace industry, optical and electronic materials, nuclear power plants, as well as the cryogenic installations.1,2 Shape memory materials, such as the shape memory alloy (SMA)3–6 and shape memory polymer,7,8 as well as SMA hybrid material consisting of SMA materials and other materials,9,10 have been studied and discussed in a number of research papers. SMA is featured by the shape memory effect and pseudo-elasticity due to martensitic transformation and reorientation.11 Due to these features, Contributing Editor: Susan B. Sinnott a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.468
the SMA couplers, one of SMA actuators, show many interesting properties than the available brazed couplers. The SMA couplers can maintain a contact pressure on the surface of the pipes and it will be easier to be fitted and installed. The interesting properties including
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