Premature bearing failure in lightly built rotating machinery induced by housing compliance: Experimental evidence and contact-mechanics analysis from a ceiling fan system

Abstract

Premature bearing failures are frequently reported in lightly built rotating machinery such as ceiling fans, despite the use of high-quality rolling element bearings and the absence of classical rolling-contact fatigue damage. Field inspections typically reveal fretting marks on bearing outer races, lubricant discoloration, elevated vibration levels, and localized heating near bearing housings, yet conventional vibration-based diagnostics fail to identify discrete fault signatures. This study investigates the hidden structural cause of such failures through combined experimental measurements and numerical contact-mechanics analysis using a commercially representative ceiling fan system. Bearing housing support rigidity was systematically varied by modifying housing thickness, spot-weld density, and rib reinforcement. Experimental results show that compliant housing configurations exhibit 40–60% higher RMS vibration levels and bearing housing temperature rises of 8–12°C compared with reinforced configurations under identical operating conditions. Finite element analysis reveals that reduced housing stiffness produces non-axisymmetric bearing seat ovalisation, resulting in highly non-uniform contact pressure distributions and peak contact stress increases of approximately 30%. These pressure gradients promote micro-slip and fretting-type behaviour at the bearing–housing interface, generating frictional heat and broadband vibration amplification rather than classical defect frequencies. The combined evidence establishes housing compliance as a primary root cause of premature bearing degradation in lightly supported rotating systems. The findings explain why such failures are often misattributed to bearing quality and why traditional fault-frequency diagnostics are ineffective. Structural reinforcement of bearing housings is shown to be a more effective reliability measure than modification of bearing clearance or replacement of bearings.