Effect of Surface Coating on One-Dimensional System Subjected to Unit StepPressure Wave

摘要

The response of a one-dimensional, coated, aluminum structure subjected to a unitstep 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.