Abstract Rotating machinery failures continue to impose substantial economic, operational and safety risks across critical industries such as power generation, manufacturing, oil and gas, and aerospace, where unplanned downtime can severely disrupt production and elevate maintenance costs. This study addresses a critical gap in the field of failure management by providing a comprehensive, physics‑based investigation into the dynamic behaviour of rotating machines subjected to simultaneous rotor faults. These conditions closely reflect real industrial environments yet remain insufficiently explored in the literature. A finite element (FE) model based on Timoshenko beam theory is developed, calibrated, and validated using experimental modal and vibration data from a laboratory-scale two-stage rotor rig. Five common defects -unbalance, misalignment, shaft bow, pedestal looseness, and partial rotor rub- are examined in combined scenarios to evaluate their interactions and influence on system dynamics. The validated FE model successfully reproduces the characteristic vibration signatures observed experimentally, including harmonic responses associated with unbalance and misalignment, eccentricity‑driven amplification due to shaft bow, intermittent impact behaviour from looseness, and super harmonics and chaotic components arising from rub. The study reveals insights into how coupled faults modify dynamic responses, including location‑specific amplification near natural frequencies, speed‑dependent shifts in the dominant harmonics, and impulsive responses driven by rub-bow interactions. The findings offer significant potential for advancing vibration‑based condition monitoring, providing a foundation for improved feature selection in intelligent diagnostic systems and supporting the development of robust, physics‑informed approaches for managing rotor‑related faults in industrial machinery.
Espinoza-Sepulveda et al. (Mon,) studied this question.