Generally, there are two types of bending tests: 3-point bend and 4-point bend. The materials that are tested using the flex test method vary from metal, plastic, wood, laminates, particle board, dry wall, ceramic tile to glass. Bending tests vary greatly based on the product being tested.
There are a variety of industry standards which are mostly based on the sample material under test. Bending tests generally involve the measurement of ductility of a sample material. Bending tests may involve taking the sample material to a specific limit and determining the load measurement and its relationship to a load specification (pass/fail). Or, it may involve bending a material until the material experiences a break and determining both the load and deflection required to initiative the break limit.
Typical graph showing 3-point bend strength test: