What is a Charpy pendulum impact test?

A test for determining toughness, or the tendency of a material to resist breaking on being subjected to sudden shock. A 3 point bend test configuration, where a notched specimen is supported on both ends and an impact hammer strikes the middle to break the piece in half.

How is a Charpy pendulum impact test performed?

Typically executed on a pendulum testing machine, the Charpy impact test is performed on both notched or unnotched specimens by means of three-point support. It is standardized in ISO 179 and ASTM D6110 (the most commons). Prismatic specimens have to be produced in according to the corresponding molding material standard. The specimens can be obtained directly by injection molding or by cutting from sheet. The Charpy test standard distinguish between a configuration in which the direction of impact is parallel to dimension b with impact on the narrow longitudinal surface h*l of the specimen (edgewise) and one in which the direction of impact is parallel to dimension h with impact on the broad longitudinal surface b*l (flatwise), as shown in the figure below.
For the Charpy test, pendulum hammers in according to standard ISO 13802 are used with a nominal impact energy range from 0.5J to 50J and impact velocities of 2.9 m/s and 3.8 m/s. When a test is performed, the energy absorbed by the specimen is calculated from the difference between the pendulum hammer height over specimen before and after impact and the mass of the pendulum hammer itself.