Session: 23-02: Gas Foil Bearings I

Submission Number: 177853

Post-Manufacturing Structural Integrity Assessment and Mechanical Characterization of Foil Bearings Using Standardized Vibration Testing 

Aerodynamic foil bearings enable oil-free turbomachinery through compliant multi-layer architecture, yet this complexity creates fundamental quality control challenges. Traditional dimensional inspection verifies component geometry but cannot detect assembly-related defects that compromise operational reliability: improper screw torque, foil misalignment, coating adhesion failures, or inadequate preload. These defects, invisible to geometric measurement, directly impact bearing durability yet typically manifest only during costly field operation or safety-critical applications.

This paper establishes a non-destructive structural characterization methodology based on DIN EN 60068-2-6 standardized vibration testing. A systematic four-phase protocol applies controlled excitation across operational frequency ranges to create quantitative structural fingerprints of assembled bearings through frequency domain analysis. The approach identifies natural vibration modes, quantifies energy dissipation through multi-layer friction interfaces, and validates mechanical stability under sustained dynamic loading.

Application to representative journal bearing designs demonstrates practical feasibility with excellent measurement repeatability. Multiple distinct structural modes are identified with characteristic damping ratios indicating proper assembly. Endurance testing assesses structural stability under sustained excitation. The methodology successfully detects assembly variations that would remain hidden to conventional inspection methods.

The approach addresses what foil bearings are from a structural perspective—their mechanical architecture, assembly integrity, and internal coherence. However, structural soundness alone does not guarantee functional performance in rotating machinery. When combined with complementary functional characterization, this methodology provides complete quality control capability, bridging the gap between component fabrication and operational deployment while establishing quantitative acceptance criteria for production environments.

Presenting Author: Hossein Sadri SADAP GmbH

Presenting Author Biography: Dr. Hossein Sadri is co-founder and development engineer at SADAP GmbH, where he leads projects in rotordynamics, tribology, and oil-free bearing technologies. He holds a Ph.D. in Mechanical Engineering with a focus on tribological systems and dynamic analysis of high-speed rotating machinery. His work bridges advanced simulation and experimental validation, contributing to the development of innovative air-bearing and foil-bearing solutions for industrial applications.

Authors:

Hossein Sadri SADAP GmbH