Crashworthiness of extruded magnesium thin-walled square tubes

Axial compression tests were conducted on AZ31B magnesium and A6063 aluminum thin-walled square tubes with varied lengths and induced features at different compression rates. In compression, the magnesium tubes exhibited a "local buckling and fracture" mode, with three fracture patterns, i.e. "horizontal", "double-oblique", and "spiral" fractures. In general, the magnesium tube showed an inferior crashworthiness to the aluminum square tube. In addition, the effects of L/W ratio, strain rate and induced features on the crashworthiness of thin-walled square tubes were investigated. With an increase in the L/W ratio (L and W represent the tube length and width, respectively) from 1 to 4, the maximal force and global specific energy absorption decreased in a power-law trend for the magnesium tubes, while they remained approximately constant for the aluminum tubes. Furthermore, as the compression rate increased from 5 x10(-5) to 10 m/s, the primary crashworthiness parameters of the magnesium tubes increased in an approximately exponential manner, while for the aluminum tubes, they changed slightly. Finally, the involved induced features were proven to be not an effective method to improve the specific energy absorption of magnesium tubes, thus, more trigger types, locations, and sizes will be evaluated in future to improve the energy-absorption ability.