A design application of cored polystyrene composite material to naval construction

Abstract

This paper presents a study of the distribution of stresses and strains acting on a

prismatic ferry that makes use of an idealized composite [1] to naval employment. The structural arrangement of the ferry is minimized in order to achieve the limit of the minimum dimensions and thicknesses able to resist deformation and maximum stresses. This minimum structural arrangement was chosen in order to study the limits of the recently developed material. Calculation of stresses and strains on the vessel is conducted with the aid of a software-based on Finite Element [2] and [3] method. In order to proceed to the stresses and strains calculations the ferry was subjected to different loading conditions: one of hogging and another of sagging, assuming the same load capacity in both situations. The basic structural arrangement adopted in a base composite element is formed by two faces and an expanded polystyrene core. Equally spaced shear webs connect both laminated faces. These reinforcements and both faces are laminated with fiber glass impregnated with epoxy resin. In defining the minimum dimensions of the elements a rule of thumb [4] is used in order to start to search for the modeling of the minimum geometry and generate the results. Results of stress distribution and deformation of the hull structure are presented. It is also computed the total weight of the structure in order to compare with another structural weight. So, these same dimensions previously defined for the ferry are also used to define a structure based in a core of Divinycell® to compare the total structural weight. At last, it is concluded that the present structure [1] has a weight consistent with the lower density Divinycell, but with a much lower price than the composite structure cored with Divynicell®.