ASTM D6742
Filled-Hole Compression Fixture for Composite Laminates
ASTM D6742 Compression Fixture – Universal Grip Data Sheet (PDF)
ASTM D6742 is a practice for filled-hole tension and compression testing of multidirectional polymer matrix composite laminates. It adapts the open-hole tension and open-hole compression methods by installing a fastener or pin in the hole. Universal Grip supplies a stabilized compression fixture for the filled-hole compression (FHC) half of the practice.
What ASTM D6742 Measures
Filled-hole compression measures the compressive strength of a laminate with a fastener installed in a central hole. A filled hole behaves differently from an open hole because the fastener carries some of the bearing load, so FHC results feed bolted joint design and aerospace laminate allowables. Fastener type, fit and torque all affect results, so D6742 sets out the installation conditions that must be controlled and reported.
How the ASTM D6742 Test Works
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Prepare a flat laminate specimen with a central hole, as for open-hole compression.
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Install the specified fastener at the required fit and torque, and record both.
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Clamp the specimen between the support plates, with the fastener head and collar in the clearance cutout.
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Load the assembly through hydraulic grips or compression platens until failure.
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Calculate filled-hole compressive strength and report fastener details and failure mode.
Specimens and Setup
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Specimen geometry follows the open-hole methods that D6742 builds on; confirm it in your copy of the standard.
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Control and record fastener type, hole fit and installation torque, since all three change results.
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Make sure the fastener head and collar clear the support plates so they do not carry load.
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Check alignment so the specimen fails in compression at the hole, not by buckling or end crushing.
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Tell us specimen width and thickness, fastener size and loading method when ordering.
Universal Grip ASTM D6742 Fixture
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Support plates restrain the specimen against buckling under compression
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Clearance cutout accommodates the installed fastener head and collar
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Load introduced through hydraulic grips or end loading
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Precision-ground support faces maintain specimen alignment
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100 kN standard capacity; higher capacities on request
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Hardened steel with corrosion-resistant finish; for electromechanical and servo-hydraulic frames
Applications
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Bolted composite joint design data
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Fastener fit and torque studies
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Aerospace laminate allowables
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Material and fastener qualification
Related Standards and Products
Tell us your specimen width and thickness, fastener size, loading method and machine connection on our contact page and we will quote a D6742 filled-hole compression fixture. Request a quote
ASTM D6742 FAQ
What is the difference between open-hole and filled-hole compression?
Open-hole compression (ASTM D6484) tests a laminate with an empty hole. Filled-hole compression adds a fastener or pin in the hole, which supports the hole edges and changes how the laminate fails. Designers use both to understand bolted joints.
Does this fixture cover filled-hole tension too?
No. This is the compression fixture. Filled-hole tension specimens are pulled in tensile grips, typically hydraulic wedge grips, in the same way as open-hole tension (ASTM D5766).
Why does fastener torque matter?
Clamp-up from the fastener restrains the laminate around the hole and can raise or lower strength. D6742 requires fastener type, fit and torque to be controlled and reported so results can be compared.
How is load applied?
The specimen is loaded through hydraulic grips or by end loading between compression platens, while the support plates prevent buckling. Tell us which method your lab uses.
Can I use my open-hole compression fixture?
The FHC fixture shares its specimen geometry approach with open-hole compression fixtures, but it needs clearance for the fastener head and collar. Send us your fastener size and we can confirm what will fit.