A Novel Preparation Method of Composite Bolted T-Joint with High Bending Performance Based on the Prepreg-RTM...

Area of Science:

• Materials Science
• Composite Materials Engineering
• Mechanical Engineering

Background:

• Developing advanced composite structures requires innovative joining techniques.
• Bolted T-joints are critical components in various engineering applications.
• Existing methods for composite T-joints face limitations in performance and manufacturing.

Purpose of the Study:

• To develop a novel polymer composite bolted T-joint using a prepreg-resin transfer molding (RTM) co-curing process.
• To evaluate the bending performance of the novel T-joint against conventional designs and aluminum alloy counterparts.
• To characterize the mechanical properties and failure mechanisms of the developed T-joint.

Main Methods:

• A co-curing resin system comprising 9368 epoxy resin (prepreg) and 6808 epoxy resin (RTM) was formulated.
• A novel bolted T-joint with internal skeleton and external skin was fabricated using the prepreg-RTM co-curing process.
• Experimental bending tests were conducted on novel T-joints, conventional RTM T-joints, and 2A12 aluminum alloy T-joints.

Main Results:

• The co-curing resins showed good compatibility. The novel T-joints exhibited excellent interface quality without defects.
• Failure modes included skin-skeleton separation and base panel fracture, with load transfer between components.
• Novel T-joints demonstrated significantly higher initial stiffness (1.65x), damage initiation load (5.89x), and ultimate load (3.45x) compared to conventional T-joints.
• Relative to aluminum alloy T-joints, the novel T-joints showed 1.44x higher initial stiffness and 2.07x higher ultimate load considering density.

Conclusions:

• The prepreg-RTM co-curing process is effective for fabricating high-performance polymer composite bolted T-joints.
• The novel T-joint design offers substantial improvements in mechanical properties over conventional composite and aluminum alloy joints.
• The study highlights the potential of this novel joint for structural applications demanding high strength-to-weight ratios.