Accession Number : ADA338293

Title :   An Examination of a Subsurface Impact on a Floating Ice Sheet.

Descriptive Note : Final rept.,

Corporate Author : NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD

Personal Author(s) : Conley, Judy A.

PDF Url : ADA338293

Report Date : NOV 1997

Pagination or Media Count : 88

Abstract : An examination is made of the influence that various parameters impose upon the structural dynamics of a floating ice sheet due to the initial impact of a large mass. The Ritz method is employed to formulate a simple shape function to approximate a solution of the plate equation, subsequently used to represent the static displacement, obtain bending stiffness, and appropriate the fundamental frequency by the principle of minimum potential energy. Fluid inertia is incorporated by assuming the mass of a hemispherical volume of fluid, associated with the effective radius of the displaced shape, distributed as a function of the displaced shape of the plate. A dynamic formulation of a two degree-of-freedom system is made and shown equivalent to two separate one degree-of-freedom systems because of the huge disparity between the two masses due to the fluid inertia influence. Each separate system provides solutions for different issues of the study. An inelastic collision represents the global impact loading influencing the general bending of the ice plate. The local crushing deformation on the underside of the ice plate, found using both a Hertz contact solution and linear approximation, depicts the initial impact force. The influence of parameters for each system is quantified.

Descriptors :   *ICE, *FLOATING BODIES, FUNCTIONS, VOLUME, GLOBAL, INERTIA, IMPACT, DYNAMICS, PARAMETERS, STRUCTURAL PROPERTIES, MASS, DISPLACEMENT, FORMULATIONS, SHAPE, POTENTIAL ENERGY, HEMISPHERES, SUBSURFACE, COLLISIONS, CRUSHING.

Subject Categories : Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE