Charpy impact test

[1] The test was pivotal in understanding the fracture problems of ships during World War II.

In 1901, Georges Charpy proposed a standardized method improving Russell's by introducing a redesigned pendulum and notched sample, giving precise specifications.

[5] The apparatus consists of a pendulum of known mass and length that is dropped from a known height to impact a notched specimen of material.

The size of the sample can also affect results, since the dimensions determine whether or not the material is in plane strain.

An exact DBTT may be empirically derived in many ways: a specific absorbed energy, change in aspect of fracture (such as 50% of the area is cleavage), etc.

For these reasons, impact tests are not widely used for assessing the fracture-resistance of low-strength materials whose fracture modes remain unchanged with temperature.

Impact tests on natural materials (can be considered as low-strength), such as wood, are used to study the material toughness and are subjected to a number of issues that include the interaction between the pendulum and a specimen as well as higher modes of vibration and multiple contacts between pendulum tup and the specimen.

The impact energies of high-strength materials other than steels or BCC transition metals are usually insensitive to temperature.