Experimental Study of Four-Point Contact Ball Bearing with Deformable Rings

Abstract

When a ball bearing is designed with thin rings or is mounted in a flexible housing, the assumption of rigid rings is not true anymore. In this article, an experimental study is presented and a comparison with a numerical model is performed. The numerical approach is based on the coupling between a semi-analytical code and a finite element (FE) model that computes the deformation of the rings and housings. The numerical model accounts for ring ovalization, raceway opening, change of conformity, and structural displacements of the whole assembly. The experimental setup allows investigation of the load–displacement behavior of a four-point contact ball bearing submitted to a static thrust loading. Displacements are measured by an optical method (stereo-correlation) that enables comparison of the surface deformation of the two tested bearings and computation of the rigid-body displacement of the inner ring with respect to the outer ring. A comparison between experimental results, numerical results, with and without consideration of ring and housing stiffness, is presented. The numerical results show the importance of the housing stiffness in the modeling, even with standard ball bearings with relatively large and thick rings. Good agreement between measured quantities and numerical results was found. This permits the prediction of the real nonlinear bearing stiffness (load–displacement curve) with a reasonable margin of error.

KEY WORDS:

• Four-Point Contact Ball Bearing
• Slewing Bearing
• Flexible Rings
• Finite Element Analysis
• Experiments
• Bearing Stiffness

NOMENCLATURE

D	=	Ball diameter
f	=	Curvature ratio
i, o	=	Inner, outer ring
R	=	Circular path radius
ref, th	=	Reference, thin ring
	=	Free contact angle
	=	Displacement along x
	=	Ring rotation