Public Defence in Mechatronics, M.Sc. Lorenzo Giorio

Machine fault diagnosis for large rotating machinery can improve the design, monitoring, and diagnostics in industrial systems, aiming to reduce maintenance costs, downtime, and safety hazards. Bearings, key components in rotating systems, directly impact system dynamics and may endure damage during operation and roundness errors during manufacturing and assembly, causing unwanted vibrations that reduce production efficiency and product quality. In the Industry 4.0 context, rolling bearings equipped with accelerometers can function as a sentry for the whole rotor system, monitoring both internal bearing damage detection and possible anomalies of the external rotor system.

This dissertation details the installation, sensor integration, and testing of a medium-sized industrial bearing test-rig at the Politecnico di Torino’s Laboratory of Mechanics. An analytical model of the rotor-bearing system was created and validated using experimental data from the test rig, allowing the identification of vibrational features from defects, able to perform component- and system-level monitoring. A dataset was created for condition monitoring of medium-size spherical roller bearings with various localized defects.

Noise reduction in experimental vibration signals was also investigated based on the Discrete Wavelet Transform (DWT). The results from a DWT parameter screening identified appropriate parameters for the detection of localized bearing defects.

The dissertation further examined the effect of bearing installation shaft geometry on the inner ring roundness errors. The so-called roundness error stacking methodology, which assesses the roundness error of the inner ring raceway based on the roundness error of the tapered shaft and the inner ring thickness variation, was validated through experimental activity performed at Aalto University’s ARotor Lab. The results showed that unmounted bearing inner ring roundness is irrelevant to the final raceway roundness, and that bearing manufacturers should focus on minimizing the thickness variation of the bearing inner ring. The study also assessed 3D conical grinding on tapered seats to correct roundness errors, showing a significant reduction in inner ring raceway roundness errors and rotor’s subcritical vibrations compared to previously published methodologies.

Doctoral Student: Lorenzo Giorio

Opponent: Prof. Sanjin Braut, University of Rijeka, Croatia

Opponent: Prof. Francesco Frendo, University of Pisa, Italy

Custos: Prof. Raine Viitala, Aalto University School of Engineering, Department of Energy and Mechanical Engineering 

The public defense will be organized online on Zoom and in person in Room C. Ferrari, Department of Mechanical and Aerospace Engineering (DIMEAS), Polytechnic University of Turin,  Italy.

The thesis is publicly displayed 10 days prior to the defense in the publication archive Aaltodoc of Aalto University. 

Contact information of doctoral student: 

Doctoral theses in the School of Engineering: https://aaltodoc.aalto.fi/handle/123456789/49