Izod Impact Test – Specimen Dimensions

Specimen Dimensions for ASTM and ISO Standards

A single-point test called “Notched Izod Impact” evaluates a material’s resistance to being struck by a swinging pendulum. The kinetic energy required to start a fracture and keep it going until the specimen is fractured is known as Izod impact. Izod specimens have notches to stop the specimen from being damaged by impact. This test can be used to compare materials for overall toughness or to quickly and easily check whether a material meets specific impact qualities.

ASTM requires a specimen that is 64 x 12.7 x 3.2 mm (212 x 12 x 1/8 inch) in size. The most typical specimen thickness is 3.2 mm (0.125 inches), however, 6.4 mm (0.25 inches) is preferable since it is less prone to crushing or bending. The specimen’s notch has a depth of 10.2 mm (0.4 inches). 

Impact energy according to ASTM is measured in J/m or ft-lb/in. By dividing the impact energy in J (or ft-lb) by the thickness of the specimen, the impact strength is obtained. Typically, the test result is the mean of 5 specimens.

The Type 1A multi-purpose specimen with the end tabs removed serves as the ISO standard specimen. The final test sample is 80 x 10 x 4 mm in size. The specimen has an 8mm depth under the notch.

The ISO impact strength unit is kJ/m2. By dividing the area under the notch by the impact energy in J, one can compute the impact strength. Typically, the test result is the mean of 10 specimens.

The harder the material, the higher the final numbers.

Video 01: Demonstration of Izod impact test

Video 01: Demonstration of Izod impact test

Comparative Analysis of Notch Groups:

The specimens with a notch at a 45-degree angle showed a 55% greater impact resistance than the parts with a 90-degree notch.

Products Tested in Testing Labs

• Rigid plastics
• Plastic insulating material
• Glass fiber reinforced plastic