Abstract:
Acoustic signatures of ground combat vehicles are very important to their survivability. In the low-frequency range of 10--200 Hz, the structure-borne acoustic radiation is mainly due to the track force/moment inputs. Full-vehicle models were developed to numerically simulate the radiated acoustic signature as well as the interior noise levels of a new composite combat vehicle at its design stage. Boundary-element method was used to compute the radiated sound pressure in the semianechoic condition after mapping normal vibration velocities (calculated from a finite-element model) onto the vehicle's surfaces [Z. Wu and E. Shalis, ``Acoustic signature prediction of combat vehicle using finite and boundary element methods,'' SPIE's 1996 Symposium on Smart Structures and Materials, 26--29 Feb. 1996, San Diego, CA]. The numerical computation is quite intensive since a large number of frequency points is required. A matrix interpolation procedure was used where the actual number of frequency loops are reduced substantially. It is done by initially computing the solution matrices at prescribed key frequencies and then computing the matrices at the intermediate frequencies using a quadratic interpolation. [This work was partially funded by a U.S. Army SBIR contract granted to Automated Analysis Corp.]