The Blast Behavior of Fiber Reinforced Thermoplastic Laminates

This article presents the results of a series of blast tests on a carbon fiber-reinforced poly-ether-imide (PEI) and a glass fiber-reinforced PEI composite. Initially, the fracture properties of the two composite systems were characterized through a series of flexural and interlaminar fracture tests. Blast testing was then undertaken on a ballistic pendulum facility, capable of measuring the impulse imparted by the plastic explosive. Delamination, localized fiber buckling, fiber fracture, and shear failure at the boundary of the clamped plates were identified as the primary failure mechanisms in the laminates, with their severity depending on the panel thickness and the applied impulse. Delamination was very localized along the center plane of the laminate, a reflection of the very high interlaminar fracture toughness of these composites. The critical impulse for rear surface fiber fracture has been found to increase rapidly with laminate thickness for the range of panels considered here. The impulses associated with the onset of rear-surface fiber fracture and complete failure of the target were similar, suggesting that rear surface fiber fracture is a pre-cursor to complete failure in these laminates. Limited tests on the glass fiber-reinforced PEI system showed that it offers a superior blast resistance to its carbon fiber counterpart.