Plastic deformation of ship plate subjected to repeated patch loads at different locations - Elastoplastic numerical analysis and design equation

Abstract

Ship structures may be subjected to repeated random patch loads at different locations. Under these circumstances, ship plates will have large accumulated permanent deformations, which will result in some serious negative effects on their work and safety performance. Therefore, the elasto-plastic response of ship structure under repeated patch loads at different locations are studied by using finite element method. The permanent deformations of plate in the whole loading and unloading process are investigated. In addition, the residual stress and plastic strain states of the panel and stiffeners are studied based on a typical wheel-on-deck interaction scenario. Moreover, according to Hughes's hypothesis, the equivalent method between repeated patch loads at different locations and full uniform pressure load is studied. Considered the influence of plate slenderness, the improved formula for equivalent load coefficient is proposed, showing a good correlation with experimental data and numerical results. The proposed equivalent method can be used for estimating the permanent deformations of ship structures under repeated patch loads at different locations in ship life.