Fully Elastic Analytical Modeling of Reinforced Cylinders
Abstract
Modeling of fluid-loaded cylindrical shells is crucial to understanding the performance of undersea vehicles. Advanced models of these structures can lead to more efficient designs with regard to target strength and radiated noise metrics. This research effort will extend the low frequency engineering models of a reinforced cylindrical shell to a high frequency fully elastic model with added improvements to include external coating and internal rib designs. Ribreinforced shells are used in a variety of applications. They can be found in undersea vehicles, industrial pipes, hydraulic lines and marine piers. Reinforcement is typically added to thesestructures as a method to increase stiffness without adding significant mass. Adding reinforcement changes the structural response of almost any system, and the forces that are introduced by the reinforcement need to be included in an analytical or numerical model thatpredicts the corresponding response. The inclusion of ring stiffeners in the cylinder increases the stiffness in all three cylindrical directions and changes the character of the infinite cylinder response from a (purely propagating) single longitudinal term expression into a (partiallyreflective) multi-longitudinal term expression due to the forces of the stiffeners interacting with the mechanical wave motion in the shell. Historically, research in this area has been divided into two separate approaches: (1) the spatial extent of the stiffener is very short compared to the periodicity of the stiffeners, or (2) the spatial extent of the stiffener is relatively long compared toits periodicity. Work in the first area, i.e., short stiffeners, is abundant and various systems have been analyzed. Free wave propagation of periodically ring stiffened shells has been studied using finite element analysis applied to various different ring geometries that all had relatively small spatial extent to determine natural frequencies and modes shapes of ring-stiffened shells.The free vibration analysis of thin cylindrical shells with ring stiffeners that have non-uniform eccentricity, and unequal spacing was investigated using a Ritz analytical method, experimental testing, and finite element analysis where the stiffeners have a small spatial extent. The ultimate objective of this research effort is to derive and analyze a high frequency target strength model ofa rib-reinforced fluid-loaded cylindrical shell with and without an external coating and two characteristic rib spatial extent cases.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 23, 2016
- Source ID
- N000141612750
Entities
People
- Steve Southward
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech