Development and Validation of an AMH-ISMA System for High-efficiency Impact Synchronous Modal Analysis

Impact synchronous modal analysis (ISMA) for rotating machinery is hindered by variability in manual impact hammers, causing phase errors and harmonic interference. We aim to improve repeatability and suppression efficiency to enable industrial deployment. We propose an ISMA approach driven by an automated modal hammer (AMH). A real-time, open-loop AMH-ISMA control system lets the workflow command on-demand impacts at a target force, while a refined phase-adaptive ISMA algorithm triggers impacts at the optimal rotor phase. The goal is to obtain high-quality frequency response functions (FRFs) with few impacts. Bench tests at 20 and 30 Hz achieved harmonic suppression rates exceeding 90%, peaking at 96.75% at 30 Hz. The method identified three target modes using eight impacts and delivered clean FRFs with reduced cyclic load. Integrating AMH with ISMA improves phase accuracy, repeatability, and test efficiency, reducing required impacts while increasing suppression. The AMH–ISMA approach is a practical and reliable option for rotating machinery diagnostics and modal testing in industrial settings.