In this study, we developed a long split Hopkinson pressure bar (LSHPB) for mechanically characterizing soft materials at intermediate strain rates. Using a proper pulse shaper, a loading pulse over 3 ms was produced for compression experiments on a PMDI foam material at the strain rates in the order of 10/s. The pulse shaping technique minimized the dispersion effects of stress wave when propagating through such a long bar system. Consistency of stress-strain curves obtained from the LSHPB and an MTS in the same strain rate range shows that a gap currently existing in intermediate strain-rate range is closed by the introduction of the LSHPB.

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Crack initiation and propagation along interfaces are influenced by interface morphology under quasi-static loading conditions. In this article, the loading rate and surface topography effects on energy dissipation during dynamic fracture of an aluminum/epoxy interface were experimentally investigated. Four-point bending specimens with a precrack on the interface were dynamically loaded at high rates with stress waves. The aluminum side of the interface on the specimen had four surface roughness levels. The study of surface morphology effects at high rates is the original contribution of this research. The results indicate that surface morphology significantly affect the energy dissipation during the dynamic fracture of the interface. At a specific roughness, fracture toughness and energy dissipation increase with increasing loading rates.

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