The compressive failure of various glasses under uniaxial shock loading has
been the subject of much recent discussion. Evidence of failure occurring
behind a boundary that follows a shock front has been accumulated by Bourne
and co-workers, and this boundary has been called a failure wave. The vari
ations in material properties across this front include complete loss of te
nsile strength, reduction in shear strength, lowered acoustic impedance and
sound speed, and opacity to light. While these observations are generally
held to be true, there has been no universally agreed mechanism for the pro
cess or processes that give rise to the failure. This work presents the res
ults of plate impact experiments that aim to identify the mechanism by whic
h the failure wave propagates in soda-lime glass and a fully filled lead gl
ass. Internal interfaces within the glasses show different effects in the t
wo materials that shed light upon the mechanisms that operate. The failure
wave propagates only after a delay in soda-lime glass, and the failed stren
gth of the material is increased at the inner interface compared with that
at the impact face. While the failed strength of the second tile is greater
, there is no delay in initiating fracture in the filled glass.