The figure shows a test specimen fixed between upper and lower grips. The knife edges of an extensometer contact the specimen at two points.

To properly design a structural or mechanical component, the engineer must understand and work within the characteristics and limitations of the material used in the component.

Materials such as steel, aluminum, plastics, and wood each respond uniquely to applied loads and stresses. To determine the strength and characteristics of materials such as these requires laboratory testing.

One of the simplest and most effective laboratory tests for obtaining engineering design information about a material is called the tension test.