Seminar Schedule – Spring 2019

Tuesday, April 16, 2019
Time: 3:30 – 5:00pm
Place: ASE 1.126

Wide-band Characterization of the Linear Dynamic Behavior of Heterogeneous Anisotropic Viscoelastic Structures. Application to the Piano Soundboard

Pierre Margerit, Ecole Polytechnique, Palaiseau, France

The presented work is motivated by the replacement of wood by composite material in the design of the piano soundboard. The main focus is on the characterization of the mechanical properties of both replaced and replacement materials in a wide frequency range, taking into account anisotropy, heterogeneous and viscoelastic behavior. The proposed method applies in three steps: (i) measurement of the free response field of the specimen; (ii) extraction of reduced data via signal processing methods; (iii) formulation of inverse problems based on the reduced data. First, the framework is implemented for modal analysis. From the transient response of the specimen, modal shapes, frequencies and dampings are extracted. Some parameters of a corresponding model of the structure can then be identified by solving an inverse eigenvalue problem based on the modal data. Second, the framework is applied to the harmonic response of beams. Wave propagating in the structure are extracted and the related wavenumber used to identify apparent complex engineering constants as a function of frequency. Third, the method is applied to the harmonic response of plates: traveling waves are characterized by a wavevector. The extracted wavevectors are used to build experimental dispersion surfaces, from which simple plate model parameters can be identified. The ability to identify a local anisotropic thin plate behavior is shown.

For further information, please contact Dr. K. Ravi-Chandar at ravi@utexas.edu or (512) 471-4213.