than 0.6. Standards ISO 12135: Metallic materials. Unified method for the determination of quasi-static fracture toughness. ISO 12737: Metallic materials. Determination of plane-strain fracture toughness. ISO 178: Plastics—Determination of flexural properties. ASTM D790: Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials. ASTM E1290: Standard Test Method for Crack-Tip Opening Displacement (CTOD) Fracture Toughness Measurement. ASTM D7264: Standard Test Method for Flexural Properties of Polymer Matrix Composite Materials. ASTM D5045: Standard Test Methods for Plane-Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials. See also References Materials testing Mechanics