Dynamic Characters Analysis Of Cylindrical Roller Bearing Under Short-time Overload Condition

Overload conditions that the working loads is several times over the rated static load in a short time is usually happens in space bearings, such as rocket engine and steering engine drive. The internal high stress has great influence on space bearing service life. Under short-time overload condition, the contact area between the rolling element and raceway is going to produce plastic deformation. The bearing contact force and deformation lie in an elastic-plastic non-hertz contact. The reciprocal action of rolling elements will result in a damage accumulation of plastic deformation. Hence,the low-cycle fatigue problem caused by cycle elastic-plastic strain should be taken into consideration when designing this kind of bearing. Aiming at overload characteristics of space bearings, based on the cylindrical roller bearing, analysis its dynamic performance under this special condition, which can provide the important design guide for rolling bearing under overload condition.The dynamic performance of cylindrical roller bearing under overload is analyzed by numerical simulation method. A cylindrical roller bearing nonlinear elastic-plastic contact finite element model is established under overload condition by large finite element analysis software ANSYS and ANSYS/LS-DYNA, and the influence of different applied load and rotate speed on elastic-plastic contact stress-strain field distribution between bearing elements, bearing vibration characteristics and cage slip ratio is analyzed. The contact stress and strain formula in the elastic and plastic stage of cylindrical roller bearing is given based on Hertz contact theory and elastic-plastic mechanical theory, the study shows: stress concentration will occur at end part of roller under overload condition, with the increase of overload coefficient, the degree of stress concentration will increase remarkably. Depth ofVMmax,? andst? will increase with the increase of overload coefficient. The permanent deformation of every contact areas will increase in nonlinear with the increase of overload coefficient and the permanent deformation has a cumulative effect in the operation of bearing. Permanent deformation is the main influence factors on bearing vibration under overload condition and the greater of permanent deformation, the more severe of bearing vibration. When the overload coefficient is greater than 1.5, cage slip ratio is about zero and overload coefficient has little effects on cage slip ratio. Rotate speed of bearing has a great influence on plastic deformation, bearing vibration, and cage slipratio under overload condition, in order to guarantee cylindrical roller bearing has good dynamic performance under the overload condition, rotating speed of bearing should be controlled under 3000r/min. The measurement of permanent deformation of the bearing after static pressure test and the bearing vibration test verifies that the contact stress and strain formula in the elastic and plastic stage can be applied for the plastic deformation of cylindrical roller bearings under light overload and the finite element method is more suitable for all overload conditions.