ASTM D5766 Open-Hole Tensile Strength of Polymer Matrix Composite Laminates

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.

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.

• 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.
• To learn more, purchase ASTM D5766