Flexural Bend Fixtures

Flexural and bend tests are commonly used to test the stiffness, yield, and general strength characteristics of plastics, metal, ceramics and other rigid materials. We offer both 3 and 4 point configurations capable of a variety of spans and force ratings. We offer both general purpose and application specific fixtures.

TestResources Test Systems, Testers and Testing Machines as well as Instron®, MTS®, Tinius Olsen® and virtually any testing machine will perform bend or flexural tests when equipped with the correct accessories.

Flexure tests monitor behavior of materials in simple beam loading; or transverse beam tests. Specimens are supported as a simple beam, with the compressive load applied at midpoint, and maximum fiber stress and strain calculated. The three point bending flexural test measures bend or fracture strength, modulus of rupture, yield strength, modulus of elasticity in bending, flexural stress, flexural strain, flexural stress strain materials response. Flexural strength represents the highest stress experienced within the material at its moment of rupture.

There are many standard test methods: ASTM D-797 (elastomers), ASTM A-438 (cast iron) ASTM D-86 (glass), ASTM C-674 (fired whiteware), (ASTM A-360, steel products), welds (ASTM E-190), fiberboard (ASTM D-1037).

Test parameters to configure a test system include load, speed of loading, test method type, support span, sample geometry, and maximum deflection of the test. Test sample thicknesses and types affect equipment requirements.

Test beams are loaded at mid-span (three-point loading) or at two positions equidistant from the two supports (four-point loading). 3-point loading is a favorable configuration, but centered loading should be spread out to avoid local stress concentration. The length of beam typically is a ratio of 16:1. To spread loading use a large contact radius. ASTM D790 specifies 5 mm (0.197 inch) radii, and some ASTM draft documents specify 3.2 mm (0.125 inch).