The unacceptable dispersion of rounds exhibited in test firings of the Phalanx CWIS motivated the study of the structural dynamics of the gun. A detailed finite element model of the gun was built, based on design input from the gun's manufacturer and from inspection of an actual gun. The model allowed the calculation of the normal modes of vibration for the non-rotating gun, and transient dynamic response to simulated round firing (75 Hz. firing rate) was calculated. The finite element model allowed, for the first time in the guns 30 year engineering history, the diagnosis of the dynamics of the breech assembly supported in bearings, inside the gun housing. The calculated normal mode shapes provided valuable insight into possible structural mechanisms leading to round dispersion. In fact, the finite element analysis results identified the bearings as likely causes of round dispersion due to the flexibility associated with the bearing load paths.
Sponsor: Naval Surface Warfare Center
This project received two letters of "Recognition of Excellence in Finite Element Modeling" from Naval Surface Warfare Center, Dahlgren, and White Oak Divisions.
This project was the basis for two theses:
