Evaluating the ductility and fracture toughness of a material
The flexural bend test is a qualitative test that is used to evaluate both the ductility and soundness of a material. Bend tests provide a simple way to describe the material's ability to resist cracking or other surface irregularities during one continuous bend. No reversal of the bend force is normally employed when conducting these tests.
The three or four point bending test, also known as the flexural test, provides values for the modulus of elasticity in bending Ef, flexural stress σf, flexural strain εf and the flexural stress-strain response of the material. The main advantage of a three-point flexural test is the ease with which specimens can be prepared and tested. However, the results of the testing method are sensitive to the specimen geometry, loading and strain rate.
The fracture toughness of a specimen can also be determined using a flexural test. The stress intensity factor is located at the crack tip of a single edge notch bending specimen. There are several reference documents that detail bending/flexural testing methods for a variety of materials and Bose® ElectroForce® test instruments have been utilized for a variety of these types of applications.
E6 Terminology Relating to Methods of Mechanical Testing
E8/E8M Test Methods for Tension Testing of Metallic Materials
ISO 12135: Metallic materials. Unified method for the determination of quasi-static fracture toughness
ISO 12737: Metallic materials. Determination of plane-strain fracture toughness
ASTM D790: Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials
ISO 178: Plastics—Determination of flexural properties
ASTM E1290: Standard Test Method for Crack-Tip Opening Displacement (CTOD) Fracture Toughness Measurement
"Chapter 4 Mechanical Properties of Biomaterials". Biomaterials - The intersection of Biology and Material Science. New Jersey, United States: Pearson Prentice Hall Bioengineering