To tackle the problem of the longitudinal strength of composite superstructures, the finite element analysis method is used to study their longitudinal bending characteristics and design requirements.

First, an analysis is made of the longitudinal strain distribution along the height direction of a simplified hull model with different lengths and the equivalent elastic moduli of superstructure materials, and the quadratic function is used to perform nonlinear fitting. Second, the design requirements of composite superstructures are proposed based on the fitting results and explained in terms of both structural size and material properties. Finally, based on the concept of bending moment effectiveness and national military standards, a superstructure method with different elastic moduli and lengths is proposed that fully participates in longitudinal bending determination.

The results show that glass fiber and carbon fiber reinforced plastic reach the longitudinal strength requirements of superstructures, and composite superstructures longer than 0.3 times the length of the hull should be included in section stiffness checks.

The results of this study can provide references for the future design of naval ships with composite materials.