Electronic speckle pattern interferometry developed for automated modal analysis of dynamic objects

Finite element (FE) analysis is an established method for designing resonant dynamic components such as tuned ultrasonic components of simple shape (blocks and cylinders). Validation of FE models has relied on contact and non-contact, normal-to-surface vibration measurement instruments, such as accelerometers and Laser Doppler Vibrometers, which have proved far from ideal in the analysis of ultrasonic components tuned to deliver predominantly in-plane surface vibration response in the longitudinal mode. This papa presents the results of complete modal analysis of high power ultrasonic machining components using electronic speckle pattern interferometry (ESPI) to measure three mutually orthogonal components of surface vibration response. Wholefield interferometric vibration amplitude and phase data is automatically transferred into modal analysis software, allowing the extraction of modal parameters and dynamic coefficients, and providing accurate correlation and validation of FE models.