ASTM D5379
Iosipescu Shear
Test Fixture
ASTM D5379 – Standard Test Method for Shear Properties of Composite Materials Using the V-Notched Beam Method - PDF
Theory
ASTM D5379 defines a shear testing procedure for composite materials, including carbon fiber-reinforced polymers, ceramics, and advanced metallic composites. Developed in the 1980s, this method remains one of the most established shear testing techniques for composite materials. In recent years, ASTM D7078 (V-Notched Rail Shear Test) has gained prominence as an alternative, particularly when edge crushing at the specimen’s loading face is a concern. ASTM D5379 is used for more rigid samples while D7078 is for floppier samples.
This test utilizes a small, V-notched specimen subjected to shear loading perpendicular to the normal plane. The test is conducted under a controlled displacement rate using a compression testing machine to generate consistent and repeatable results.
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Specimen Geometry
The standard specimen measures approximately 3 inches (76 mm) in length and features symmetrical V-notches at both the top and bottom, machined at a 45-degree angle. This notched configuration serves to localize shear stress within the central region of the specimen, ensuring that failure occurs within the intended shear plane.
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Test Setup and Equipment
ASTM D5379 testing requires the use of an Iosipescu shear fixture, specifically designed for compatibility with a Universal Testing Machine (UTM) in Compression mode. Universal Grip Company (UGC) provides a comprehensive range of shear fixtures compliant with ASTM standards, ensuring precise alignment and load application.
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Data Analysis and Calculations
Shear strength is determined by dividing the peak load observed during testing by the cross-sectional area of the shearing region. In addition to shear strength, the ASTM standard outlines supplementary calculations, including shear modulus and strain analysis. To enhance measurement accuracy, strain gauges can be affixed directly to the specimen, capturing localized shear strain and deformation characteristics. Video Extensometers can also be used instead of strain gauges, saving time and materials costs.
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Related Standards
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