Numerical load generation, vibration analysis, and acoustic signature prediction of a composite combat vehicle

Abstract

Acoustic signatures of ground combat vehicles are very important to their survivability. In particular, low-frequency tones can be used to identify vehicles beyond the line of site. In the range of 10-200 Hz, the structure-borne acoustic radiation is mainly due to the track force/moment inputs. In this work, full-vehicle models were developed to simulate numerically the radiated acoustic signature as well as interior noise levels at its design stage. The loads applied on the hull of the vehicle were computed from a specialized code previously developed by the U. S. Tank Command. It simulates the interaction of the hull, sprocket, idler, roadwheels, roadarms, torsion bars, and track. The loads generated from this analysis comprise the excitation for the vibration calculations. The 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. A description of the entire process of generating the loads, incorporating them in the finite-element analysis, and using the vibration results for the acoustic signature of the army vehicle is presented. [Program partially funded by a U. S. Army SBIR contract.] [See NOISE-CON Proceedings for full paper.]