cross section crash boxes

(a) (b)
Figure 3.13. a) Schematic of the buckling initiator and b) experimental and simulation
deformation of the tube with and without buckling initiator (Source: Zhang,
et al. 2009).
Bambach et al.(Bambach, et al. 2009) studied the dynamic crushing of thin
walled composite steel-carbon fiber reinforced plastics (CFRP) square tubes. Carbon
fiber layers were braided in two different combinations on the same sample: one
transverse and one longitudinal layer (1T1L), and two transverse and two longitudinal
layers (2T2L). Two deformation modes, ductile stable progressive deformation without
and with partial delamination, were observed (Figure 3.14). It was reported that CFRP
braiding of steel square tubes increased the dynamic mean crushing load by 82%. SEA
values of composite steel-CFRP square tubes were found 52% higher than those of steel
square tubes and 94% higher than those of CFRP square tubes.
The effect of damage parameters on the axial crushing behavior of 6060T5 thin-
walled aluminum square extruded tubes was investigated (Galib, et al. 2006). Tensile
tests on five different geometries of 6060T5 Al tube material were performed to identify
the damage parameters of Lemaitre's damage model. Simulation results were compared
with those of experimental impact tests. It was noted that experiments showed negative
loads on the deformation history (Figure 3.15(a) arrows). This was attributed to the
restriction of the vertical differential displacements of the constraints in the simulation.
Numerical absorbed energy values agreed with those of experiments (Figure 3.15(b)).
The used damage model also well represented the failed sections of the tested square
6060T5 square tubes (Figure 3.15(c)).
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