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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

Flexure tests on composites (3-point and 4-point flexure tests) are performed to easily determine important mechanical characteristics.
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2-Point Flexure Tests

ISO 2493-1, DIN 53121, ISO 5628, DIN 55437-3, DIN 19304
Determines the bending stiffness of paper and cardboard to ISO 2493-1, DIN 53121, ISO 5628, and DIN 19304, together with the technical quality of creasings to DIN 55437-3
to 2-Point Flexure Tests

3-point flexure test

3-point flexure tests in the following applications: Solid board, paper-based composites, or core tests are carried out in accordance with company standards.
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4-point flexure test

DIN 53121, ISO 5628
Bending stiffness of corrugated board to DIN 53121 or ISO 5628
to 4-point flexure test

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.
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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.
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Testing machines for flexure tests

Other Tests

Tensile Test

The tensile test is used to characterize the strength and deformation behavior under tensile load.
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.
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Fatigue test

In the fatigue test, material fatigue is evoked through a cyclic load with corresponding test frequency.
to Fatigue test

Hardness Testing

In hardness testing, is the resistance of a body to the indentation by another (harder) body is measured.
to Hardness Testing

Impact test

Impact tests are short-term tests, which provide information on the failure behavior of materials or components.
to Impact test

Drop weight test

The drop weight test is a mechanical test, in which a defined weight falls onto a specimen from a specified height.
to Drop weight test

Biaxial test

In the biaxial test—in contrast to the uniaxial tensile test—a specimen is loaded via two load axes.
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Test methods for sheet metal forming

Test methods for sheet metal forming provide characteristic values for metalworking and metal processing and include tests such as cupping tests, earing tests and hole expansion tests.
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