Flexural performance of composite grid panels with deep ribs

This paper reports on the flexural performance of an innovative composite grid panel composed of glass fiber-reinforced polymer face skins and deep glass fiber-reinforced polymer ribs with a trapezoidal cross-section. Three-point and four-point bending experiments were performed to demonstrate the feasibility of the composite grid panels under concentrated loads. Compared with the composite grid panels without skins, maximum increases in the ultimate load, and initial bending stiffness of the composite grid panels of approximately 68.2% and 306.7%, respectively, were achieved with the existence of both upper and lower skins. Furthermore, an analytical analysis was carried out to predict the initial bending stiffness and mid-span deflection of the composite grid panels. A comparison of the analytical and experimental results showed that the analytical model accurately predicted the flexural performance of the composite grid panels subjected to three-point and four-point bending. Failure mechanism maps were constructed to predict the mechanical response and failure modes of the composite grid panels. Moreover, the validated model was used in a parametric analytical study to further estimate the effects of various parameters on the flexural performance of the composite grid panels. The results demonstrated that the initial bending stiffness can be significantly improved by increasing the trapezoidal section ratio, face skin thickness, and grid height.