EFFECTS OF A TRANSLATING LOAD ON A FLOATING PLATE—STRUCTURAL DRAG AND PLATE DEFORMATION

The elastic deformation of a structural plate floating on water caused by a translating three-dimensional load is investigated. The problem is akin to the landing and take-off of aircraft on a structural or ice sheet. The initial-boundary-value problem is solved analytically using a free-surface condition that incorporates the flexural rigidity of the plate. The three-dimensional load is modeled as an axisymmetric, translating pressure distribution. The time-dependent analytical solution is used to obtain the unsteady drag of this moving pressure, if it exists, as well as its asymptotic behavior at large time. The behavior of the transition of the drag near a critical speed related to the minimum celerity of the free waves of the hydroelastic system is examined. Asymptotic analysis shows that the drag attains a discontinuous but finite value as the translation speed approaches the critical speed, an essential difference from some existing two-dimensional results. The growth rate of the plate slope is found to be weakly singular, like log t, for large time. Comparisons with published experimental data for plate deformation are made for the case of an ice sheet. The agreement is very favorable. Implications on the operation of floating runways are discussed.