Crush energy absorbing characteristics of graphite/epoxy square tubes

In the present study, effect of stacking sequence on the peak load and the average sustained load of graphite/epoxy square tubes is investigated using the crush test. In the crush test, compressive load is applied on the top of composite square tubes under the stroke control with cross-head speed of 0.3mm/sec. The experimental data shows that the square tube with [(+45/45)(4)](T) has the highest peak load. Whereas tubes with [(0)(8)](T) and [(90)(8)](T) showed poor crush energy absorbing characteristics, tubes with [(0/90)(4)](T) had the improved peak load and the average sustained load. In addition to the experimental survey, the finite element analysis is used to estimate the peak load of the graphite/epoxy square tubes with [(0/90)(4)](T) and [(0+/- 45/90)(2)](T). The first buckling mode of the tube is superimposed to the perfect geometry and the distributed compressive load is applied on the top of the tubes for failure analysis. The lowest applied compressive load that makes failure criteria equal to one is regarded as the peak load of each tube. The estimated peak loads of the composite tubes with [(0/90)(4)](T) and [(0+/-45/90)(2)](T) agreed well with the measured peak loads using the failure analysis.