Extraordinary states of highly localised pressure and temperature can be generated upon the collapse of impulsively driven cavities. Direct observation of this phenomenon in solids has proved challenging, but recent advances in high-speed synchrotron radiography now permit the study of highly transient, subsurface events in real time. We present a study on the shock-induced collapse of spherical cavities in a solid polymethyl methacrylate medium, driven to shock states between 0.49 and 16.60 GPa. Utilising multi-MHz phase contrast radiography, extended sequences of the collapse process have been captured, revealing new details of interface motion, material failure and jet instability formation. Results reveal a rich array of collapse characteristics dominated by strength effects at low shock pressures and leading to a hydrodynamic response at the highest loading conditions.
This Article contains errors. In the legend of Figure 1, "(a) Spectral flux per bunch through an on-axis 1 mm 2 area delivered by Beamline ID19 in the four bunch mode (40 mA storage ring current), including 2.8 mm diamond and 1.4 mm aluminium filtering. The total flux was 1.2 × 10 9 photons s −1 mm −2 on-axis. " should read: "(a) Spectral flux per bunch through an on-axis 1 mm 2 area delivered by Beamline ID19 in the four bunch mode (40 mA storage ring current), including 2.8 mm diamond and 1.4 mm aluminium filtering. The total flux was 4 × 10 7 photons/bunch/mm 2 on-axis. "
This paper presents a description and the demonstration results of a custom-designed bespoke Split-Hopkinson Pressure Bar (SHBP) which has been installed at the ID-19 beamline at the European Synchrotron Radiation Facility (ESRF). Building upon recent advances in realtime x-ray imaging, this system enables the study of dynamic mechanical phenomena through ultra-high-speed x-ray phase-contrast radiographs captured every 528 ns with high spatial-temporal resolution. By adding synchronized strain gauges measurements in the same experiment, bulk stress-strain behaviour can be correlated to the local processes underlying deformation, damage and failure. This article briefly outlines the newly installed hardware and its design. Demonstration experiments showing damage development in dynamically loaded Ti-6Al-4V and concrete are presented to underline the potential of an SHBP to be used in combination with synchrotron-based high-speed hard x-ray imaging. K : Inspection with x-rays; X-ray radiography and digital radiography (DR); Trigger concepts and systems (hardware and software) 1Corresponding author.
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