Investigation into the Spall Strength of Cast Iron
The spall strength of cast iron has been investigated by means of planar plate impact experiments conducted in a vacuum. A single stage gas gun was utilized to drive projectiles to velocities between 100 and 300 m/sec, resulting in low to moderate shock loading of the cast iron specimens. Measurement of the stress histories were made with the use of commercial manganin stress gauges that were imbedded between the back face of the cast iron specimen and a low impedance backing of polycarbonate. Spall strength values were calculated utilizing the measured peak stress and minimum stress pullback signals captured in the stress history. Spall strengths were found to vary between 0.98 and 1.45 GPa for the cast iron tested. Postmortem analysis of recovered specimen has provided insight into the evolution of spall failure in cast iron and shed light on the varying nature of the spall strength values calculated. It was determined that the lower bound of strength values were associated with small scale microfailure, while the upper bound values corresponded to complete spall fracture.
KeywordsCast Iron Wave Speed Stress History Spall Strength Shear Wave Speed
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