Powder Epoxy for One-Shot Cure, Out-of-Autoclave Applications: Lap Shear Strength and Z-Pinning Study

Large composite structures manufactured out-of-autoclave require the assembly and bonding of multiple parts. A one-shot cure manufacturing method is demonstrated using powder epoxy. Lap shear plates were manufactured from powder epoxy and glass fiber-reinforced plastic with four different bonding ca...

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Bibliographic Details
Published in:Journal of composites science 2021-09, Vol.5 (9), p.225
Main Authors: Noble, Thomas, Davidson, James R., Floreani, Christophe, Bajpai, Ankur, Moses, William, Dooher, Thomas, McIlhagger, Alistair, Archer, Edward, Ó Brádaigh, Conchúr M., Robert, Colin
Format: Article
Language:English
Subjects:
Adhesion
Adhesives
Autoclaves
Bonded joints
co-curing
Composite structures
Costs
Curing
Digital imaging
Fiber pullout
Fiber reinforced polymers
Glass fiber reinforced plastics
Glass-epoxy composites
Investigations
Lap joints
lap shear strength
Manufacturing
Mechanical properties
Military aircraft
out-of-autoclave manufacturing
Pinning
powder epoxy
Production methods
R&D
Research & development
Resins
Scanning electron microscopy
Shear strength
Viscosity
Z-pinning
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Summary:Large composite structures manufactured out-of-autoclave require the assembly and bonding of multiple parts. A one-shot cure manufacturing method is demonstrated using powder epoxy. Lap shear plates were manufactured from powder epoxy and glass fiber-reinforced plastic with four different bonding cases were assessed: secondary bonding using standard adhesive film, secondary bonding using powder epoxy, co-curing, and co-curing plus a novel Z-pinning method. This work investigates the lap shear strength of the four cases in accordance with ISO 4587:2003. Damage mechanisms and fracture behavior were explored using digital image correlation (DIC) and scanning electron microscopy (SEM), respectively. VTFA400 adhesive had a load at break 24.8% lower than secondary bonding using powder epoxy. Co-curing increased the load at break by 7.8% compared to powder epoxy secondary bonding, with the co-cured and pinned joint resulting in a 45.4% increase. In the co-cured and co-cured plus pinned cases, DIC indicated premature failure due to resin spew. SEM indicated shear failure of resin areas and a large amount of fiber pullout in both these cases, with pinning delaying fracture phenomena resulting in increased lap joint strength. This highlights the potential of powder epoxy for the co-curing of large composite structures out-of-autoclave.
ISSN:2504-477X
2504-477X
DOI:10.3390/jcs5090225