Crash Testing Of Advanced Composite Energy-Absorbing, Repairable Cabin Subfloor Structures

This paper describes an exploratory development research program to investigate advanced composite energy absorbing (EA) subfloor structure concepts that are also repairable and readily producible. The EA subfloor concepts were developed in a step-by-step manner that began with element design support tests and culminated in full-scale drop tests of a repaired crash-damaged composite cabin. The three EA concepts investigated were an improved sandwich (double pandown) design, an integrally tube-stiffened design, and a sine wave design. Based on the element testing, two of the EA concepts, the double pandown sandwich and the sine wave were selected and successfully drop tested in a full-scale repaired composite cabin test section. Comparisons of the cabin drop test results and the KRASH analysis depended on the accuracy of the load-deflection data from design support tests. The correlations show good agreement with the double pandown sandwich subfloor, but KRASH showed higher accelerations and correspondingly lower deflections than test for the sine wave subfloor due to a reduction in EA efficiency for the inclined impact test condition.