ASTM D5766 Open-Hole Tensile Strength of Polymer Matrix Composite Laminates
Standard At A GlanceMaterials
ASTM D5766 determines the open-hole tensile strength of multidirectional composite coupons. The composite coupon geometry has to be in accordance with test method ASTM D3039. ASTM D5766 is designed to produce tensile results on multidirectional polymer matrix composite laminates mainly used in the aerospace industry for material specifications, research and development, quality assurance, and structural design and analysis.
Materials Testing System
Because the forces required for ASTM D5766 testing are relatively high, a floor model universal testing system such as Instron's 6800 Series is recommended. The properties of composite materials are highly directional, making it especially necessary to test with a system that is well-aligned and repeatable. An AlignPRO fixture and precision manual or hydraulic wedge grips are necessary in order to test specimens within alignment requirements and without slippage.
ASTM D6484 Test Setup
Bluehill Universal Software
2580 Series Load Cell
2742 Series Hydraulic Wedge Grips
Testing Tips and Tricks
This testing is performed in accordance with ASTM D3039, but instead of a uniform coupon, the specimen is modified with a centrally-located hole. When calculating the ultimate tensile strength based on the cross sectional area, the hole's presence is disregarded.
ASTM D5766 requires that the specimen coupon have multidirectional fiber orientations in a minimum of two directions. Typical test results include the ultimate tensile strength, the width of specimen-to-hole diameter ratio, hole-diameter-to-coupon-thickness ratio, and, if desired, the edgewise percent bending in accordance with ASTM D3039.
The only valid failure mode in determining the ultimate tensile strength is one that passes through the prefabricated hole in the test coupon. A break outside of this location does not deliver valid test results.
Instron 6800 Series Universal Testing Systems provide unparalleled accuracy and reliability. Built on a patent-pending Operator Protect system architecture with an all-new Smart-Close Air Kit and Collision Mitigation features, the 6800 Series makes materials testing simpler, smarter, and safer than ever before.
Instron’s universal testing machines are designed to perform the most common types of testing used in the composites industry, including but not limited to in-plane tensile, through thickness tensile, interlaminar shear, compression in end, shear, or combined loading, and compression after impact.
Available in 100 and 250 kN capacities, Instron's 2716-028/30 precision manual wedge grips provide reliable gripping for a wide range of materials as well as repeatable alignment that meets Nadcap requirements.