Using Basalt Fibers in Fabricating Thin Isogrid-Stiffened Composite Structures and Determining Their Flexural Response

The interest of grid-stiffened composite (GSC) structures has grown rapidly in recent years for their superior properties of high specific stiffness and strength, superior load-bearing capacity, and excellent energy absorption capability. In the last decade, basalt has emerged as a contender in fibrous composites. The lack of scientific information about the utilization of basalt fibers on GSC fabrication was the driving force for the selection of this study. Furthermore, with the aim of evaluating the possibility to replace glass fibers, three -point bending test was conducted on iso-GSC panels reinforced by E-glass and basalt fibers. Two different types of iso-GSC panels containing a similar volume fraction of the unidirectional fibrous reinforcements (E-glass and basalt) in the epoxy matrix of the ribs were fabricated. According to load-displacement graphs, the bellow trend was observed when the samples loaded from the skin side; following an initial linear region and reaching a load peak, the curve was abruptly dropped and then showed a typical absorbed energy region. It would be worth mentioning that in these structures, a considerable energy absorption was observed after the primary failure related to the load peak. The results obtained on the two iso GSC panels were compared in terms of flexural properties (stiffness, load bearing capacity, and energy absorption) demonstrating a higher performance of the basalt-reinforced sample compared to the one reinforced by E-glass. This suggests the possibility to apply basalt as a possible replacement for E-glass which is nowadays largely employed in the fabrication of GSC structures.