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What is Flexural Testing?

Flexural properties are an essential factor in the determination of stiffness from a compression or tensile angle. In bending, a beam is subjected to both compression & tensile stresses. The flexural test is useful for gaining knowledge of pound force, Psi and tangent modulus factors. Currently, 2 procedures (A & B) exist for this standard and both are used for qualifying incoming resins and compounds. Usually a 3" long x 1" wide by 1/8" thick specimens are used for qualification. Other configuration specimens are used, but it depends on the molded parts or raw resin supplied.

1.1 The Flexural Testing  methods (ASTM D 790) cover the determination of flexural properties of un-reinforced and reinforced plastics, including high-modulus composites and electrical insulating materials in the form of rectangular bars molded directly or cut from sheets, plates, or molded shapes. The Flexural Test methods are generally applicable to both rigid and semi-rigid materials. However, flexural strength cannot be determined for those materials that do not break or that do not fail in the outer surface of the test specimen within the 5.0 % strain limit of these test methods. The Flexural Test methods utilize a three-point loading system applied to a simply supported beam.

1.1.1 Flexural Test Procedure A, designed principally for materials that  break at comparatively small deflections.

1.1.2 Flexural Test Procedure B, designed particularly for those materials, that undergo large deflections during testing.

1.1.3 Flexural Test Procedure A shall be used for measurement of flexural properties, particularly flexural modulus, unless the material specification states otherwise. Flexural Test Procedure B may be used for measurement of flexural strength only. Tangent modulus data obtained by Flexural Test Procedure A tends to exhibit lower standard , deviations than comparable data obtained by means of Flexural Test Procedure B.

1.2 Comparative Flexural Tests may be run in accordance with either procedure provided that the procedure is found satisfactory for the material being tested.

1.3 The Flexural Testing values stated in SI units are to be regarded as the standard.

Specimens are usually Injection Molded or can come from molded parts (depending on configuration).

Should you need additional information about CRT Laboratories' Flexural testing capabilities please contact us via our RFQ Form or call us at (714) 283-2032. You may fax a request for a proposal at (714) 283-1365.