Polymer foams are widely used in the transportation, packaging and construction sectors. Thanks to their low density, they allow to reduce the mass of structures while keeping a good rigidity (sandwich structures) and offering thermal (insulation) and mechanical performances (impact resistance).

Consisting of a small fraction of material compared to that of the gas they trap, cellular materials and polymer foams in particular have a high compressibility, which translates into a mechanical behavior in volume change very specific to this type of material. When used in sandwich structures as energy absorbers, polymer foams are subjected to multiaxial mechanical loadings for which volume change (compressibility) but also shape change (shear) of the foam are observed. In order to propose a behavioral model capable of describing this type of multiaxial behavior, it is therefore necessary to experimentally study the volume change behavior of polymer foams.
The work presented here proposes to use an experimental device called “hydrostatic cell” placed in an electromechanical compression machine and allowing the hydrostatic pressurization of a polypropylene foam sample under quasi-static conditions. For this, the sample is introduced into the closed “cell”, filled with an incompressible fluid and then pressurized by the piston of the compression machine.

The research work presented here was also interested in studying the influence of the geometry on the mechanical behavior in volume change of the Polypropylene foam.