Abstract:

In a car frontal impact, the crash box and bumper act as a buffer to first absorb a portion of the impact energy and then transfer the remaining downward to the body structure, while the structures enabling the optimal energy absorbing capacity to advance the frontal crashworthy safety are concerned. Thin-walled flip tubes implement energy absorption under compressive loading by the flipping process with lower averaged and peak forces, whichis expected to benefit buffering impact. However, the kinetic complexity in flipping process is likely to cause structure tilting overleadingincreasing structural stiffness and instability to fail its expected energy absorption quality. As stable flipping concerned, based on the study of the energy absorption characteristics of multiple flip structures and aluminum foam, a split flip tube structure filled with aluminum foam is presented. The comparative studies of the stability and energy absorption effects for the structures with or without foam cores are carried out. The result shows that the aluminum foam-filled flip tubes have much improved effects in both stability and energy absorption, while the application simulations express that using them as the car energy-absorbing boxes has the same good properties, especially by the worst cases of impacting with tilting angles.Finally, design optimization for the structural parameters is obtained by the NSGA-II algorithm.

Key words: flip tube, flipping stability, foam aluminum, energy absorbing box