High-Bandwidth Measurement and Validation of Bar and Plate Dynamics
Abstract
The Air Force Research Laboratory Munitions Directorate (AFRL/RW) is performing a series of studies to validate the ability of codes to accurately predict the impulse response of simple mechanical structures, i.e., impact-loaded bars and plates, over a wide frequency range. The modal responses of both structures are predicted using finite element codes and simple analytic calculations. An experiment on isolated (i.e., free-free) structures using impulse hammers as the excitation is described. The outputs of high bandwidth strain gages and accelerometers monitor the elastic wave propagation in the structures. The corresponding frequency-domain characteristics (e.g., the power spectral density of each sensor as well as the transfer functions between them) are measured over a wide frequency range in a cylindrical bar. Leakage is found to significantly reduce sensor coherence over a broad spectral band. Use of an exponential window restores the coherence in the original signal, leading to a broadband coherence below 10 kHz, but this approach broadens the modal peaks observed and introduces errors in damping estimates. The initial results from an ongoing effort to characterize the modal response of a hanging plate are also presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 04, 2008
- Accession Number
- ADA484340
Entities
People
- Jacob Dodson
- Jason Foley
- Martin Schmidt
- Preston Gillespie
- Yasmin Besonia
Organizations
- Air Force Research Laboratory