3-Point and 4-Point Bending Fixtures for Uniform Moment Flexural Testing

These fixtures are used with universal testing machines to evaluate the bending properties of materials under controlled loading. They cover both 3-point and 4-point configurations, so one fixture family handles routine and more demanding flexural work.

They suit any material that must be characterized in bending. To match a set to your work, request a personal quote.

In a 4-point setup, two loading rollers apply force at equal distances from the supports, which produces a region of constant bending moment between the load points. Because there is no shear force in that middle region, failure is driven by pure bending.

That clean stress state is the main reason to choose 4-point. Learn more about our tensile testing equipment.

A 4-point test spreads the load across two noses and removes shear from the middle section, giving a more even stress distribution than the single-line load of a 3-point test. This is valuable when shear would otherwise influence the result.

It is the preferred method where uniform bending stress matters. To choose the right configuration, talk to our team.

The even stress distribution makes 4-point testing well suited to:

• Brittle materials
• Plastics and composites
• Concrete beams

These benefit from loading that minimizes shear in the gauge region. Explore the full grips and fixtures range.

The right choice depends on a few factors:

• Whether shear in the gauge region must be minimized
• The material, such as brittle composites or concrete
• The standard, such as ASTM D6272 or C78

Those point to the configuration you need. Email sales@tensilemillcnc.com.

Common reference standards include ASTM D6272 for plastics and ASTM C78 for concrete flexural testing. ASTM C78 evaluates the flexural strength of concrete using a simple beam with third-point loading, a classic 4-point arrangement.

The fixture is matched to the method and specimen. See our standards and certification.

They measure flexural modulus and deformation behavior with as little effect from shear loading as possible. Flexural modulus describes bending stiffness, and the clean stress region also supports the study of fracture characteristics.

This makes 4-point a strong choice for stiffness and fracture work. Learn more about our tensile testing equipment.

The assembly includes two upper loading rollers and two adjustable lower supports. The rollers apply the load at two points while the supports hold the specimen, and rollers keep friction low as the specimen bends.

This layout is what creates the constant-moment region. Learn more about our tensile testing equipment.

Yes. The support span can be set to match specimen size and testing requirements, which lets you meet the span-to-depth ratios that flexural standards call for.

Correct span setup is essential for a valid modulus. To set up a test, request a personal quote.

Between the two loading noses the bending moment is constant and shear is effectively zero, so any failure in that region is caused by bending alone. This gives a cleaner measure of flexural modulus and strength, especially on brittle materials.

Removing shear is the key advantage of 4-point loading. To discuss your material, talk to our team.

They are used in construction material testing, composite manufacturing, and research environments to study bending performance and fracture under stable, repeatable loading.

Each of these relies on controlled, comparable flexural conditions. Explore the full grips and fixtures range.

Yes. Concrete beams are a primary use, typically under ASTM C78 with third-point loading. The fixture is sized and rated for the loads concrete flexural testing requires.

This makes it a fit for construction materials labs. To set up a concrete test, request a personal quote.

You can request a personal quote or order online. Sharing your material, standard, and specimen size lets us recommend the right fixture and span.

For a configuration matched to your testing, request a personal quote.