Dynamic or Impact Tests
Impact tests are designed to measure ability of the equipment or its parts to withstand shock loads. It involves a pendulum swinging down from a specified height, h1 to strike the test piece and fracture it. The length, h2 to which the pendulum rises after breaking the test piece is a measure of the energy used in breaking. After calculating the energy required to break the specimen, the impact strength can be found by the formula.
Impact strength = Energy in fracture /Cross-section area at notch
Charpy Test
For Charpy test, a notched specimen is mounted as a simple supported beam, and heavy pendulum is allowed to strike the specimen from fixed height. The notch is on the face directly opposite to where the pendulum strikes the test piece.
Izod Test
In this case a notched specimen is held in a vice in the form of cantilever and a heavy pendulum is allowed to strike the specimen from a fixed height. The blow is struck on the same face as the notch at a fixed height above it.