Effects of partial-grooving on the performance of spiral groove bearings: analysis using a perturbation method

The perturbation method has been extended to investigate the effects of partial-grooving on the performance of spiral-grooved spherical and conical bearings. A ‘partial-grooving ratio’ (PGR), which has a value of 0 for a fully-grooved bearing and a value of 1 for a plain bearing, has been introduced to represent the degree of partial-grooving. It has been found that the load capacity and stiffness of a bearing are not significantly affected by partial-grooving as long as the value of PGR is below 0.2. When PGR increases above 0.2, the axial load capacity and axial stiffness will decrease sharply whereas improvements in radial load capacity and radial stiffness may be achieved. The study has also revealed that radial stability of a bearing is improved by partial-grooving, provided PGR is not too large. However, a bearing becomes inherently radially unstable if the bearing gap is not completely filled with lubricant, regardless of it being fully or partially grooved.