We have been investigating the response of structures
to the combined loading of fragments and pressure. Sources of pressure loading include
blast, hydrodynamic ram or combustion of vapors inside (say) a fuel tank. Typically the
plate is first perforated by fragment impact and then pressure loaded. Under the effect of
pressure loading, cracks propagate from the hole enlarging it or even leading to plate
rupture. We have characterized this weakening effect of the hole by testing, engineering
models and numerical simulation. The effect is expressed in terms of hole enlargement or
in terms of the decrease in the pressure pulse required to rupture the plate. Our results
relate this effect to the material properties and thickness of the plate, the size,
location and number of the holes and the pressure loading. Our results can be used to
design more survivable structures and more lethal weapons.
Good agreements are shown below between test results and ABAQUS simulations for the
case of one hole, two holes, and three holes in the plate. For the case of a plate with
one hole, we also have developed an engineering model that predicts crack length as a
function of plate and loading parameters. |
