Impulse Excitation of Piezoelectric Patch Actuators for Modal Analysis

摘要

Impact hammer testing is a fundamental technique in experimental modal analysis, allowing a fast estimation of the dynamic properties of a structure in its linear range. However, human error can limit the accuracy of the measured frequency response functions when the tests are conducted manually, as the FRFs are influenced by the locations and orientation of the hits, as well as the magnitude of the impact if the test piece is nonlinear. Piezoelectric patch actuators can be permanently attached to a structure and provide a controllable means of excitation, thus reducing the uncertainties introduced by manual testing, and allowing testing on structures in operation. This paper therefore investigates the possibility of using piezoelectric patches to simulate impact testing, and of their use as a minimally intrusive on-board monitoring system allowing to extract the natural frequencies, damping, and mode shapes of flexible structures. The methodology has been verified on a free-free beam, and validated against standard testing methods and analytical results, demonstrating its viability. It was then applied to the modal analysis of an academic blade disk, and led to the successful extraction of its resonance frequencies and damping values.