An energy dissipating mechanism for crushing square aluminium/CFRP tubes

A platen with cutting blades was introduced as a new energy dissipating mechanism to simultaneously cut and crush square bare CFRP tubes and CFRP tubes wrapped externally with aluminium sheets. The specially designed and manufactured platens with four round tip blades, four sharp tip blades and eight round tip blades were used to reduce the initial peak crushing force and increase the energy absorption of CFRP tubes. Notches were introduced at one end of tubes to control the location of the initial failure. Experimental results showed that the deformation mode of CFRP tubes and aluminium sheet-wrapped CFRP tubes that were crushed by platens with blades was a combination of splaying progressive and transverse shearing failure mode. More damage was observed to CFRP plies when tubes were crushed by using round tip blades. Tubes cut and crushed by a platen with eight round tip blades had a lower initial peak crushing force, higher mean crushing force, larger energy absorption and higher specific energy absorption in comparison with counterpart tubes crushed by flat platens. A comparison between the new trigger mechanism proposed in this study (cutting blades) and other different trigger mechanisms used in published literature was made.