Izodprøver

Izodprøver, or Izod impact tests, are a class of pendulum impact tests used to assess a material’s resistance to sudden fracture when struck. The method is widely employed for plastics and is also used for metals and composite materials. In a typical test, a standardized notched specimen is clamped in a support and struck by a swinging pendulum. The energy absorbed by the specimen from the pendulum until fracture is measured and reported as the impact strength, usually expressed in joules or kilojoules per square meter for notched samples (Izod impact strength).

Standard test methods exist, with ASTM D256 being a prominent example for plastics. The Izod test is related to the Charpy impact test, but differences in specimen mounting and notch orientation mean that results are not directly interchangeable between the two methods. Interpreting Izod results requires care, because factors such as temperature, notch geometry, specimen orientation, and testing rate can influence the measured impact energy.

Uses and significance include quality control in plastic production, material selection in product design, and comparative screening of formulations, fillers, or additives. The test provides a quick, relatively inexpensive measure of a material’s ability to withstand sudden loads. However, it provides only a single aspect of toughness and may not capture all failure modes, so it is typically used alongside other mechanical tests in a broader materials-evaluation program.

Historically, the test is named after developers from the early 20th century and has become a standard tool in materials testing, especially within the plastics industry.