With industrial partner Arianegroup, we studied the mechanical behavior of three propellant-like materials. Two materials were made of an inert matrix with about 55% of sifted 250 microns ammonium perchlorate (AP) or RDX particles. The last material was the polymer matrix filled with about 20% of aluminium 3 microns particles and filled with AP fillers. These materials were tested in uniaxial tension and showed very different stress-strain responses.
The local damage around the particles is strongly dependent on the matrix/filler adhesion properties as one can see here. For the similar macroscopic applied strain, according to the filler/matrix properties, polymer fibrils may persist around the particles or complete matrix debounding may be witnessed.
A tool was designed to generate microstructures for finite element simulations with possible damage at the matrix/filler interface.
Using a cohesive zone model to account for the damageable interface at the filler/matrix, it was possible to:
- Show how the adhesion properties impact the local damage across the microstructure
- Make a link between the local damage and the macroscopic stress-strain response
- Recognize the adhesion properties of the three materials of interest
See the reference for more details.