Drop-weight impact towers are frequently used to generate low velocity impact damage. Typically, the falling mass will be instrumented, containing a load-cell for measuring the load-time trace. The output signal can be integrated to yield a load-displacement trace, a more useful type of curve. Impact loading results in the following failure mechanisms in composites: delamination, fibre fracture, matrix cracking and fibre-matrix debonding. There are no specified tests for characterizing the impact response of composites and many different procedures are adopted.
It is often difficult to achieve very low energy impacts with a drop weight impact tower. For low energy impacts, one can use a pendulum.