Flexure test
Along with the tensile test and the compression test, the flexure test is one of the types of loading most frequently occurring in practice. It is therefore of considerable importance when it comes to testing a wide range of materials. Flexure tests are accordingly used in determining the mechanical properties of steel, plastics, wood, paper, ceramics and other materials.
Why flexure tests?
Flexure tests are performed to determine important mechanical characteristics. In particular, this test is used for tests on brittle materials, since the specimen causes metrological problems during the tensile test due to its failure behavior.
What can you determine using a flexure test?
Depending on the material, different material properties can be determined. The results of the flexure test show, in particular, the material behavior near the surface of the specimen. The deflections measured are approximately four times greater than the extensions in a tensile test.
Typical test results are:
- Strength testing of materials
- Calculation of the flexural stress and strain
- Flexural modulus
- Bending stiffness
- Flexural resistance
- Stress at 3.5 % elongation
- Stresses and elongations at the yield point and at specimen break
- etc.
2-point flexure test
The 2-point flexure test kit is suitable for testing of paper, cardboard, and films. It is used to determine the bending stiffness (using the beam method) and bending resistance of paper, board, and cardboard, e.g. to DIN 53121, ISO 5628 and DIN 19304, plastic films for example to DIN 53350 and coated textiles.
3-point flexure test
The loading device consists of two parallel-positioned anvils for the specimen and an upper anvil positioned centrally between the anvils. The upper anvil applies the load to the specimen.
Depending on requirements (standard), the anvils and upper anvils must have fixed, rotating or rocking mountings to enable testing in accordance with specifications.
The test is mainly used for tough and elastic materials.
To minimize frictional influences during testing the anvils can be mounted so as to rotate around their longitudinal axis. Rocking mountings can be used with the upper anvil and anvil supports to ensure that they are parallel to the specimen.
4-point flexure test
As with the 3-point flexure test, the 4-point flexure test kit consists of two parallel-positioned anvils which, depending on the test requirements, must have fixed, rotating or rocking mountings.
The difference from the 3-point flexure test lies in the way in which the load is applied to the specimen. This is done via 2 upper anvils located symmetrically to the anvils. The bending moment is then constant between the two force application areas.
This test is primarily used to determine the modulus of elasticity in bending for brittle materials.
