Mitigation of Helmet Vibration

Acentech will leverage its expertise and considerable experience in solving vibration and noise problems to develop and provide finite element models and modal and transfer function analyses of the E-2D flight helmet to address the problem of pilot exposure to excessive vibration/noise related primarily to propeller blade passage tones. High-fidelity ANSYS FE models of the helmet composite shell including foamed liner components will be developed and used to predict structural resonance frequencies and mode shapes as well as shell vibration and ear noise levels for point and distributed pressure loads on the shell. Helmet testing on an artificial head utilizing modal and transfer function analyses will be used to characterize the helmet dynamic response to point force and distributed pressure loads, to provide validation of the FE models and to identify, along with the FE models, whether shell resonance amplifies tonal cockpit noise/vibration components. The FE models will be used in Phase II to optimize mitigation approaches that reduce pilot exposure, including structural modification of the shell and enhanced helmet and liner sound attenuation. Other approaches such as tuned vibration absorbers on the shell and active control strategies will also be evaluated for potential effectiveness and feasibility.