Flexural Strength Test

The bending strength or bending strength of a material is defined as its ability to resist deformation under load. In international standards, the maximum bending stress value obtained is defined as bending strength. For materials that deform significantly but do not break, the yield load, typically measured at 5 percent deformation or stretching of the outer surface, is determined as flexural strength. The material is under compressive stress at the concave surface and tensile stress at the convex surface.

The two basic standards used to measure flexural strength are:

• ISO 178 Plastics - Determination of bending properties
• ASTM D790-17 Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials

The values ​​obtained in the test methods presented in these two international standards rarely differ significantly. These tests also describe the method of measuring the flexural modulus of a material, that is, the ratio of stress to strain at flexural deformation.

The ISO 178 standard describes a test method for determining the bending properties of solid and semi-rigid plastics under defined conditions. This method includes a range of test rates. The method is used to investigate the bending behavior of test specimens and to determine the flexural strength, flexural modulus and other aspects of the flexural stress/strain relationship under defined conditions. This test method is mainly suitable for the following materials:

• Thermoplastic molding, extrusion and casting materials and rigid thermoplastic sheets, including filled and reinforced compounds, in addition to unfilled types
• Thermosetting molding materials and thermoset sheets, including filled and reinforced compounds.

The test methods described in the ASTM D790-17 standard utilize a three-point loading system to apply a load to a simply supported specimen. This method is used to determine the flexural properties of unreinforced and reinforced plastics, including high-modulus composites and electrically insulating materials. It is generally applicable to both rigid and semi-rigid materials. However, it is not suitable for materials that do not fracture or yield within a 5 percent strain limit at the outer surface of the test specimen.

Our organization also provides bending strength testing services with its trained and expert staff and advanced technological equipment, among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors.