Characterization of a controllable stiffness foil bearing with shape memory alloy springs.

This paper develops a shape memory alloy gas foil bearing (SMA-GFB), in which the stiffness of elastic structure and the clearance between the rotor and top foil are adjusted by the temperature of SMA springs which is controlled by electric heating and a designed cooling method. A numerical model of elastic structure composed by a series of SMA springs is conducted, and the experimental results verify that the active elastic structure can improve SMA-GFB performance. Furthermore, the static and dynamic characteristics of SMA-GFBs are predicted. The load capacity and stability of two different designs of SMA-GFB are explored based on the circumferential distribution of SMA springs. These data expand the path for the active application of SMA in gas bearings. • Shape memory alloy (SMA) is introduced into the gas foil bearing to control the stiffness of elastic structure and the clearance between the rotor and top foil. • An effective cooling method is designed to regulate the SMA spring's temperature. • The experimental results verify that proposed elastic structure can be used as an active element to adjust the performance of the SMA-GFB. • The predicted results reveal that the direct dynamic stiffness and damping coefficients in austenite phase is larger than that in martensite phase. Accordingly, the SMA springs distribution in circumferential direction affect load capacity and stability of foil bearing. [ABSTRACT FROM AUTHOR]