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Video Series: Impact Testing

Izod impact testing is a tool used in determining various characteristics such as strength, brittleness, and toughness of plastic, composite, and other polymer materials. Undergoing physical testing such as impact testing is crucial for materials in terms of quality control and specification purposes. The toughness of the material determines how well it can absorb energy. Materials such as glass or ceramics tend to be more brittle, meaning they are not as tough and break easily. Glass or ceramics would have lower absorption rates than copper or aluminum, which are not considered brittle. The toughness of a material can also be dependent on the temperature. For instance, when a material has a decrease in temperature, it becomes more brittle. Thus, to ensure accurate reading, we test at room temperature. 

For Izod impact testing, a bar is held vertically to achieve a vertical level fall and the specimen is struck near the top. The test can be run on both notched and unnotched specimens. A hammer pendulum system applies force to neat, filled, rigid, or semi-rigid polymers to determine impact energies. For a notched specimen, the pendulum strike produces a stress concentration that increases the probability of a brittle fracture. However, when an unnotched specimen is struck, it is used to evaluate unreinforced materials where a stress-concentrating notch is not desired. 

The Charpy test is another method to test for toughness of a material. It can also be run using the pendulum weighted system. However, for this test, a bar is fixed horizontally and the specimen is stuck near the middle. There are two types of notches when it comes to the Charpy test; a V-notch and a U-notch. The difference resides in the depth and radius with the U-notch having a larger depth and radius than the V-notch.  Both of the impact tests are performed in accordance with ASTM D4812, D256, D6110 and ISO 179, 180 standard methods to ensure accuracy across all industries. 

These material characteristics are used for material qualification programs, comparisons of materials for second source procurement, and to aid in the root cause analysis in material failure investigations. Find out more about our Impact Testing on our website or in our video below!