Analysis of an Angular Contact Ball Bearing Failure and Strategies for Failure Prevention
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CASE HISTORY—PEER-REVIEWED
Analysis of an Angular Contact Ball Bearing Failure and Strategies for Failure Prevention V. Murugesan . P. S. Sreejith . P. B. Sundaresan . V. Ramasubramanian
Submitted: 19 September 2017 / in revised form: 2 January 2018 ASM International 2018
Abstract Bearing failures are one of the most common failure modes in the rotating machinery and equipment. Angular contact ball bearings are widely used considering their ability to carry the loads in both axial and radial directions, durability and low friction. The smooth functioning of these bearings greatly depends on the bearing load rating, material, type of fit with which it is assembled, the operating temperature and proper installation in the assembly. This paper presents the analysis of a failure of an angular contact ball bearing used in the gas motor system of an electrohydraulic control actuator used for launch vehicle attitude control. Detailed investigation of the failure is carried out by thermal and structural modeling of the bearing assembly, and the failure cause is identified as the combination of design error, hardware deviations and improper assembly operation which led to bearing misalignment and very high loading of the first row of balls resulting in excessive heating. The failure theory explains all the observations on the parts of the failed bearing. The physics of failure is understood, corrective actions to avoid the failure are addressed, and the strategies for prevention of similar failures are evolved. Keywords Angular contact ball bearing Rotor Failure modes Interference fit Preload Fillet radius Misalignment
V. Murugesan (&) P. B. Sundaresan V. Ramasubramanian Vikram Sarabhai Space Centre, Thiruvananthapuram 695022, India e-mail: [email protected] P. S. Sreejith Cochin University of Science and Technology, Kochi 682022, India
Introduction Liquid propellant rocket engines have a number of rotating machinery such as turbo-pumps, rotary actuators, gas motors and axial piston reciprocating pumps. In such machinery, rolling element bearings are employed to allow the relative motion and support the rotor shafts on the housings, considering their load carrying capacity and friction characteristics [1]. The rolling element bearing faults are one of the primary causes of breakdown in rotating machinery [2]. The bearings will survive the predicted fatigue life, under ideal operating conditions. However, in service, bearings are subjected to harsh environments such as thermal, vibration and impact loading. The bearing can fail due to various reasons such as wrong selection of bearing with respect to the type and load rating, inadequate lubrication and the environmental conditions [3]. In most cases, bearing failures are encountered because of noncompliance with recommended practices. Insufficient attention to the assembly procedures of the bearing with the machine elements and operating methods also frequently cause failures [4]. So, the accurate definition of the bearing loads, environments, de
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