of plastics is ASTM D256. The results are expressed in energy lost per unit of thickness (such as ft·lb/in or J/cm) at the notch. Alternatively, the results may be reported as energy lost per unit cross-sectional area at the notch (J/m or ft·lb/in). In Europe, ISO 180 methods are used and results are based only on the cross-sectional area at the notch (J/m). The dimensions of a standard specimen for ASTM D256 are 63.5 × 12.7 × 3.2 mm (2.5 × 0.5 × 0.125 in). The most common specimen thickness is , but the width can vary between . See also Impact force Fracture mechanics Shock (mechanics) References Further reading BS EN ISO 180:2001 - "Plastics. Determination of Izod impact strength" BS EN ISO 13802:2006 - "Plastics. Verification of pendulum impact-testing machines. Charpy, Izod and tensile impact-testing" Continuum mechanics Fracture mechanics Materials testing