Flexible Hybrid Fastening Systems and Installation Processes
Fasteners are often installed through holes drilled in individual pieces to be joined. While significant advancements have been made in fasteners over the past several decades, construction techniques such as using composites (including wood, fiberglass, and carbon fiber), in particular, have exposed serious limitations to existing fastener capabilities. Advance fasteners are often required for dissimilar and advanced materials, especially modern composite structures. These specialized fasteners must deliver high strength and fatigue resistance, along with ease of manufacture and repair.
Description of Technology
Michigan State University has developed a hybrid fastening system with an associated installation process. The most basic form of the invention involves a standard fastener type coupled with a liquid or elastomeric insert filler material. To use the system, the fastener is installed in much the same fashion as a normal fastener and serves a similar function, with an axial load applied to ensure adequate shear strength. In addition, however, a filler material (such as polyurethane, silicone, or epoxy) is added to the joint to help seal out moisture and debris contamination and lower contact stresses, yielding better fatigue performance. Conceptually, the filler material is installed either through direct injection, or through a capsule that is installed within the joint and which opens and allows the filler to flow into the joint as the fastener is secured.
- Higher joint strength: Exhibits the combined benefits of fastener, insert, and adhesive patch elements.
- Increased fatigue performance: The lower contact stresses and filled joint helps prevent contaminant entry.
- Less sensitivity to misaligned work pieces: The filler adjusts misalignment voids.
- Better sealing against moisture and debris contamination: The filler provides a complete joint seal that is challenging when fastening composite materials.
- Less dependence on precision-drilled work piece holes.
- Composite Structures
- Wind Turbines
2 Patents issued, patent number US9,464,658 and US10,400,813
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Michigan State University