Accession Number : AD0473768


Title :   THE EFFECT OF CERTAIN DAMPING TREATMENTS ON THE RESPONSE OF IDEALIZED AEROPLANE STRUCTURES EXCITED BY NOISE


Descriptive Note : Final rept. Jan 1963-Jan 1964


Corporate Author : SOUTHAMPTON UNIV (UNITED KINGDOM)


Personal Author(s) : Mead, D J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/473768.pdf


Report Date : Aug 1965


Pagination or Media Count : 202


Abstract : Data are presented on the vibration of aeroplane structures excited by jet-noise or other random pressures. A review is made of those aspects of vibration and transmitted noise which may be alleviated by increasing the structural damping. The damping of conventional untreated structures is considered, measured values of the damping of model and full-scale structures are discussed in the light of previous studies of acoustic and rivet damping. The common practice of judging a damping treatment by the loss factor increment it produces is shown to be inadequate for contemporary treatments and thin-plate structures. Alternative criteria are derived which describe more adequately the effectiveness of the treatment in attenuating certain random and harmonic vibration phenomena. These were used to compare two commercial unconstrained treatments and to estimate the reduction of random stresses in an aeroplane structure when the treatments are added. The response of a two-dimensional flat sandwich plate with a damped core was analysed. The dependence of the modal loss factor, stiffness and criteria values on the wavelength and core properties was studied.


Descriptors :   *VIBRATION , *DAMPING , *AIRFRAMES , STRESSES , METAL PLATES , SANDWICH CONSTRUCTION , JET ENGINE NOISE , ACOUSTIC INSULATION , NOISE , ACOUSTICS , MODEL TESTS , EXCITATION


Subject Categories : Military Aircraft Operations


Distribution Statement : APPROVED FOR PUBLIC RELEASE