Dynamic tests on a cohesive and frictional material. Influence of high pressure and high strain rate on compaction and shear

Many of aggregate composites are made of small size particles mixed with a highly compliant rubbery polymer. When the loading leads to high pressures, the behaviour gets closer to this of cohesive, frictional, and compactable materials. When this kind of material is subjected to an impact, the loading domain is the case of high pressure (from 100 to 1000 MPa) and high strain rate (roughly 1000 s(-1)). An experimental study is led by using the technique of the SHPB. The specimens are small cylinders placed in a ring which creates a passive confinement by opposing to the radial displacements. The instrumentation of the ring allows to estimate the radial stress and the radial displacement. The main point is that it makes possible the follow-up of the spherical and deviatoric parts of the stress and strain tensors during the test, without restrictive hypothesis on the behaviour of the material. The results show a high sensitivity to the strain rate. The stresses evolutions show that the frictional phenomenon is sensitive even under high pressures.