buigtest

Buigtest is a mechanical test that determines a material's behavior under bending loads. It is widely used to assess flexural strength and stiffness. In a typical setup, a rectangular specimen is supported at two points and loaded either at the center (three-point bending) or at two points (four-point bending).

Measurements are made of the applied load and resulting deflection. From the data, the flexural strength (modulus of rupture, MOR) and the flexural modulus (stiffness) are derived. The test can be performed on a range of materials, including metals, polymers, composites, wood and ceramics.

Three-point bending uses a central load with a single span between supports, while four-point bending applies two loading points to create a constant bending moment in the region between the loads. The geometry of the specimen—width b, depth d, and span L—affects the results, and consistent preparation and alignment are important for comparability.

For a rectangular section, MOR is commonly calculated for a simply supported beam with a center point load as MOR = (3FL)/(2bd^2), where F is the maximum load, L is the span, b is the width and d is the depth. The flexural modulus is obtained from the slope of the initial portion of the load–deflection curve using beam theory.

Standards such as ASTM D790 and ISO 178 specify specimen geometry, testing procedures, and data reporting. Interpretations depend on material type and processing, as properties can be anisotropic or influenced by moisture, flaws, or prior treatment.