A failure analysis of foil journal bearing under low-speed operating conditions

Abstract

In this failure analysis, the bump-type foil journal bearing (BFJB) is developed with various foil materials such as spring steel EN42J, phosphor bronze, Inconel X750, and SS 316. Subsequent failure analysis of the BFJB is conducted under low-speed operating conditions to evaluate their rubbing performance using the RSM technique. The study examined rotor speed and load as variable parameters, with wear rate (WR) and surface roughness (SR) of the BFJB as output responses. Additionally, a thermal imager is used to measure the rubbing temperature of the BFJB. The results indicated that Inconel X750 demonstrated superior tribological characteristics for the BFJB. With an increase in load, the wear rate of the BFJB increased while the surface roughness decreased. Among all foil materials, Inconel X750 had the most significant impact on surface roughness. The optimal values for rotor speed (S) and load (P) to enhance BFJB performance are 500 rpm and 10 N, respectively. Under these optimal conditions, the BFJB with Inconel X750 as the foil material exhibited a wear rate of 0.0150 mg/s and a surface roughness of 2.085 μm. Moreover, the BFJB made with phosphor bronze displayed the minimum rubbing temperature.