Dynamic compression of cellular materials

Cellular structures can have excellent energy absorbing abilities and this is particularly important for where we want to reduce the effects of car collisions on their occupants or even to mitigate the effects of an explosive blast on a vehicle. SEIT has been involved in the study of the dynamic behaviour of a whole range of cellular materials to better understand their energy absorbing mechanisms. Fig 1 shows the an example of the type of cellular structure that is found with a metallic foam; in this case it is an aluminium foam although it is possible to produce these types of foams from other metals such as titanium.

X-Ray image of a metallic foam.

 

One of the challenges we have is visualising and understanding how the pores collapse during dynamic loading conditions. We can use computational tools to asses this. Fig 2 shows an example of how these foams collapse during dynamic loading after an impact at 219 m/s. The advantage of computational approaches is that we can very easily change the material parameters to understand which material properties are advantageous in enhancing the foams energy-absorbing abilities.

Computational model of the dynamic collapse of an aluminium foam with time.