How does the Charpy impact test differ from the Izod impact test?

In the field of materials testing, both the Charpy impact test and the Izod impact test are used to measure a material's resistance to sudden impact by calculating the energy required to fracture a notched specimen using a swinging pendulum.12

The primary difference between these two methods lies in how the test specimen is positioned and supported during the impact:

• Charpy Test: The specimen is held in a horizontal position, supported at both ends like a lintel over a door.12
• Izod Test: The specimen is held in a vertical, upright position, supported only at its lower end like a fence post.132

While both tests provide critical data regarding a material's impact strength and its tendency to fail at notches or flaws, engineers select between them based on the specific geometry, support requirements, and testing conditions necessary to accurately predict how a material will behave under actual service conditions.12