Warren R. Maines

Equation of state and isentropic release of aluminum foam and polyvinylidene fluoride systems

There is considerable interest in developing a better understanding of the dynamic behavior of multicomponent heterogeneous systems. This study investigates and compares the dynamic response of 21% dense aluminum foam, filled with polyvinylidene fluoride (PVDF or Kynar). Experiments were conduced in a 60 mm bore gun in a one-dimensional reverse plate impact configuration at velocities ranging from 350 m/s to 2200 m/s. The particle velocity of the backside of a thin anvil, also referred to as a witness plate, was monitored with a velocity interferometer. The resulting shock Hugoniot and isentropic release states are inferred from the particle velocity records using an impedance matching technique. The experiments indicate that the heterogeneous system achieves a wide distribution of states even though it was loaded in a one-dimensional plane-strain configuration. The system maintains its strength up to shock levels near 5 GPa, above which the PVDF appears to melt upon release. Simulations were conducted us...

High Velocity Uniaxial Strain Response of ERG Aerospace Aluminum Foam

We report the results of uniaxial strain experiments of ERG Aerospace aluminum foam, at 50% relative density up to 10 GPa. The reverse ballistic plate reverberation technique was used to obtain shock compression states of the material. In these tests, 6061 T-6 aluminum, oxygen free homogenous copper (OFHC), and tantalum were used as standard material targets and were shocked by an aluminum foam projectile traversing up to 2.0 km/s. The response of the target plates were monitored by three different velocity interferometers positioned at three different locations on the witness plate. This provided us with the compaction behavior of the foam material in three discrete locations per sample, due to the presence of porosity in the foam material.Copyright

Release states in aluminum foam

We report isentropic release states of uniaxial strain experiments and simulations on 6101 T-6 48-50% density open-cell aluminum foam compressed up to 10 GPa. Mesoscale simulations of the dynamic response of the foam are compared to experimental measurements and are used to build continuum constitutive relations. The mesoscale simulations capture the Hugoniot and the release behavior in the foam extremely well. The resulting constitutive relations built from mesoscale simulations compare favorably to those built from experimental results.