Impact strength is the ability of a material to withstand impact
or shock load.
When the time for application of load on a material is very very
small, the material experiences the load in the form of shock or
impact. This impact load is always greater than the load when it is
applied gradually on a material.
Let's take a case
stress due to gradual load on a material
= P/A
stress due to sudden load or shock load or impact load(P)
=2P/A
Impact stress is always greater than gradually induced
stress in a material.
Therefore a materials impact strength must be higher to
withstand the shock load.
