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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.

How does the flexure test work?

There are three different types of flexure tests:

  • 2-point flexure test
  • 3-point flexure test
  • 4-point flexure test

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.

In the 2-point flexure test, the specimen is gripped at one end and loaded with a test die on the exposed side.

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.

In the 3-point flexure test, the specimen is positioned on two supports and loaded in the center with a test die.

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.

In the 4-point flexure test, the specimen is positioned on two supports and loaded in the center with a test die with two points of contact.

Test tools for flexure tests

For flexure tests, ZwickRoell offers a comprehensive range of different test tools—from flexure test kits to flexure tables and dies to upper anvil holders and other accessories.

You can find a selection of test tools for flexure tests here:

Test tools for flexure tests

Flexure tests in different industries

Flexure tests
ISO 14125, ASTM D7264
Flexure tests on composites (3-point and 4-point flexure tests) are performed to easily determine important mechanical characteristics.
to Flexure tests
2-point flexure test paper
ISO 2493-1, DIN 53121, ISO 5628, DIN 55437-3, DIN 19304
Determination of the flexural strength of paper and cardboard
to 2-point flexure test paper
3-point flexure test on paper and cardboard
About factory standards
Solid board, paper-based composites and reel cores
to 3-point flexure test on paper and cardboard
4-Point flexure test on corrugated board
DIN 53121, ISO 5628
to 4-Point flexure test on corrugated board
Flexure test on ceramics
EN 843-1 and ISO 6872
The test kit is designed for flexure tests on ceramics to EN 843-1, specimen shapes A and B, and ISO 6872.
to Flexure test on ceramics
3-point flexure test kit for small plate bending test
This 3-point flexure test kit is used to perform the small plate bending test according to VDA 238-100:2017-06 for determination of the bending angle with the objective of reaching conclusions about the deformation behavior of metallic materials during forming processes with dominant bending elements (e.g. hemming operations) or during crash loading.
to 3-point flexure test kit for small plate bending test

Testing machines for flexure tests

Other Tests

Tensile Test to Tensile Test
Compression test
and compression testing machines
Compression tests are used to characterize the behavior of a material under compression load and determine different material properties, including the elastic limit, the proportionality limit, the yield point, and more.
to Compression test
Fatigue test
Definition and description:
to Fatigue test
Hardness Testing to Hardness Testing
Impact test to Impact test
Drop weight test to Drop weight test
Biaxial test to Biaxial test
Test methods for sheet metal forming to Test methods for sheet metal forming