Accession Number : ADA288237

Title :   Effect of Surface Coating on One-Dimensional System Subjected to Unit Step Pressure Wave.

Descriptive Note : Progress rept. 1 Oct 93-30 Sep 94,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Brasek, T. P. ; Kwon, Y. W. ; Shin, Y. S.

PDF Url : ADA288237

Report Date : 30 SEP 1994

Pagination or Media Count : 51

Abstract : The response of a one-dimensional, coated, aluminum structure subjected to a unit step pressure wave is studied. The coating is either an elastic material or a viscoelastic tread stock rubber of variable stiffness; it separates the structure from an air or a water medium. The stress and nodal velocity of the structure coated with different materials is compared to a system without a coating (homogeneous system). Both the stress and nodal velocity of the structure increase with a decreasing coating stiffness regardless of the coating type or bounding medium. This phenomenon indicates that the coating stiffness governs the degree of strain energy release from the structure to the medium. A softer coating appears to trap this excess energy increasing the stress in the structure. In all cases studied, the stiffer coating reduced the dynamic response of the structure when compared to the homogeneous system. A rubber shear modulus of approximately 6000 psi and greater ensured a favorable dynamic response for a coated aluminum structure enacted upon by a step pressure wave travelling in either air or water. The threshold value may vary depending upon the geometry and material properties of both the coating and the structure.

Descriptors :   *STRESS ANALYSIS, *VISCOELASTICITY, PLASTIC DEFORMATION, VELOCITY, STRESS STRAIN RELATIONS, PRESSURE GRADIENTS, WATER WAVES, ALUMINUM ALLOYS, THRESHOLD EFFECTS, FINITE ELEMENT ANALYSIS, LOADS(FORCES), STRUCTURAL MECHANICS, ALUMINUM COATINGS, DYNAMIC RESPONSE, ONE DIMENSIONAL, RUBBER COATINGS, SHEAR MODULUS, SHOCK WAVES, STIFFNESS, SURFACE FINISHING, TREADS, HULLS(MARINE).

Subject Categories : Mechanics
      Coatings, Colorants and Finishes
      Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE