Residual Strength of Composite Hulls after Impact

Abstract

Norsafe MILPRO boats operates in different waters at high speeds. The chance of hitting unknown objects e.g. floating logs is present. Being able to judge the damages and the residual strengths to these impacts are desirable. To reach this goal, the first step is to focus on the basics of how flat panels of glass reinforced polymer composites will behave. The composite hulls on the Norsafe MILPRO boats are made out of a sandwich structure which consists of two glass reinforced polymer composite skins separated by a lightweight core. Post-impact analysis of the composite skins will be studied with fo- cus on the residual strength properties. Low-velocity impact events by an impactor of a hemispherical tip on composite specimen supported by a rigid substrate will be performed. The damage tolerance of the impact event has been investigated through tensile-, compression- and flexural tests. Two laminates have been studied. A cross-ply laminate with layup [0/90]5 and a quasi-isotropic laminate with layup [(0/90/ ± 45)2 0/90]. Both laminates show a reduc- tion in the residual strength in tension, compression and bending. A quantitative damage model of predicting the impact damage out of the size of a clean circular hole has been utilized.