Processes Controlling the Dynamic Fracture of Brittle Solids,
CALIFORNIA INST OF TECH PASADENA
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A brief summary of some experimental results on dynamic fracture of brittle solids is presented. A complete presentation of the various aspects of dynamic fracture is discussed. The experimental configuration used in these experiments simulate pressurized semi-infinite cracks in an unbounded medium for the duration of the experiment 150 microsec. The pressure loading on the crack faces is achieved by an electromagnetic loading device. The principle of the method is as follows A cooper strip is doubled up and inserted into a slit machined into a large plate. A high current on the order of several thousand amperes is passed through the copper strip. The current in one leg of the strip interacts with the magnetic field generated by the other leg, and the result is a pressure force on the faces of the machined slit. The current is derived from a capacitor-inductor circuit and the time dependence of the current pulse and hence that of the pressure resembles a trapezoidal history with a 25 microsec rise time and 160 microsec total duration. This device is capable of delivering crack face pressures of up to approximately 60 MPa.