San Andres, Luis Chirathadam, Thomas Abraham Kim, Tae-Ho 2024-01-20T20:00:27Z 2024-01-20T20:00:27Z 2021-09-01 2010-03 0742-4795 https://pubs.kist.re.kr/handle/201004/131703 Engineered metal mesh foil bearings (MMFBs) are a promising low cost bearing technology for oil-free microturbomachinery. In a MMFB, a ring shaped metal mesh provides a soft elastic support to a smooth arcuate foil wrapped around a rotating shaft. This paper details the construction of a MMFB and the static and dynamic load tests conducted on the bearing for estimation of its structural stiffness and equivalent viscous damping. The 28.00 mm diameter 28.05 mm long bearing, with a metal mesh ring made of 0.3 mm copper wire and compactness of 20%, is installed on a test shaft with a slight preload. Static load versus bearing deflection measurements display a cubic nonlinearity with large hysteresis. The bearing deflection varies linearly during loading, but nonlinearly during the unloading process. An electromagnetic shaker applies on the test bearing loads of controlled amplitude over a frequency range. In the frequency domain, the ratio of applied force to bearing deflection gives the bearing mechanical impedance, whose real part and imaginary part give the structural stiffness and damping coefficients, respectively. As with prior art published in the literature, the bearing stiffness decreases significantly with the amplitude of motion and shows a gradual increasing trend with frequency. The bearing equivalent viscous damping is inversely proportional to the excitation frequency and motion amplitude. Hence, it is best to describe the mechanical energy dissipation characteristics of the MMFB with a structural loss factor (material damping). The experimental results show a loss factor as high as 0.7 though dependent on the amplitude of motion. Empirically based formulas, originally developed for metal mesh rings, predict bearing structural stiffness and damping coefficients that agree well with the experimentally estimated parameters. Note, however, that the metal mesh ring, after continuous operation and various dismantling and re-assembly processes, showed significant creep or sag that resulted in a gradual decrease in its structural force coefficients. [DOI: 10.1115/1.3159379] English ASME Measurement of Structural Stiffness and Damping Coefficients in a Metal Mesh Foil Bearing Article 10.1115/1.3159379 1 JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, v.132, no.3 JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME 132 3 scie scopus 000272388200011 2-s2.0-78149402098 Engineering, Mechanical Engineering Article; Proceedings Paper Metal Mesh Foil Bearing Stiffness Damping Parametric Identification Static Dynamic