Numerical Simulation Of Thin-walled Metallic Square Tube With Aluminium Foam Filler Under Impactload

Thin-walled metallic square tubes with aluminium foam filler was widely used in improving structure crashworthiness and reducing structure weight.Based on ansys ls-dyna simulations,researches were carried out to study the deformation and energy absorption of thin-walled metallic square tubes with aluminium foam filler subjected to impactload.The simulations was carried on from different length-width ratio,flakiness ratio of the metallic tube and different foam density-distribution and made a simulation about the response of the bumper with filled tube under impactload. The materials of metallic tube and aluminum foam were described by number 24 piecewise linear plastic hardening and number 63 crushable foam material model.Shell 163 and Solid 164 element were used to mesh the metallic tube and aluminum foam.Triggers were introduced in the simulation to make the deformation stable,but did not affect the total deformation of structure.The 1/4 model was established because of symmetry,the corresponding semmetry constraints, contact set and boundary conditions were appended in order to reduce simulation process time, increased the simulation accuracy.Compared to use the empty metallic square or aluminium foam square alone,this composite structure could decrease the weight while maintaining or even improving stiffness,shorten the length of fold caused by crushing and increase the specific absorbed energy value,so it was effective in energy absorption applications,keeping the peak force below the limit that causes damage.The numerical results were compared with the experimental result and gave an excellent agreement. So the experimental method was right.Conclusions were as follows:(1) Compared to using aluminium foam or metallic tubes alone, thin-walled metallic square with aluminium foam filler could greatly smaller von misses stress and bigger the amount of absorbing impacted-energy.(2) The longer the model length,the smaller the densities of aluminum foam filler,the thinner the thickness of metallic tube,when compressed,generated more and better regularity drapes, caused less degree destruction to the metallic tube.when impacted,the composite structure filled with different density distribution aluminum foam generated less drapes than the lower density aluminum foam filler,but more drapes than the higher density aluminum foam filler.(3) The thicker the lateral thin-walled metallic tube, when impacted,the bigger the Von misses stress;but the values of foam filler densities,different density distribution aluminum foam and the length-diameter ratio of the model had little effect on that. (4) Increasing the thickness of the thin-wall metallic tube or the value of aluminum foam density could strengthen the ability of absorption energy,but the length-diameter ratio of the model had little effect on that.The composite structure filled with different density distribution aluminum foam had a bigger ability of absorption energy than filled with lower density aluminum foam,but smaller than filled with higher density aluminum foam.(5) The effect of using composite structure instead of empty metal cylinder as the energy-absorbing component of bumper was obvious, this way could reduce the deformation of bumper and increase impacted absorbing energy.