Experimential Study on Failure Mode and Ultimate Shear Bonding Force of CFRP Plate-Steel Interface under Anchor Compression

In order to study the paste failure mode and ultimate shear bonding force of CFRP plate-steel interface anchor bonding, a single-sided shear test was carried out on a total of 15 carbon fiberboard (CFRP)-steel composite beam structure specimens in five groups. The test results show that for organic adhesives, the uniform anchoring method can improve the bearing capacity of the construction; for organic adhesives, the ultimate shearing when the specimen is peeled with inorganic glue is used. The bonding capacity is greater than that of specimens with organic adhesives.

Welding and Riveting Hybrid Bonding of 6061 Al and Carbon Fiber Reinforced Composites

Welding and riveting hybrid bonding technology was applied to join 6061 aluminum alloy and carbon fiber reinforced plastics (CFRP). The laser-arc hybrid welding process and stepped rivets were used in the experiments to reduce the impact of the poor heat resistance of composites. The effect of hybrid welding arc current on the formation and mechanical properties of 6061 Al/CFRP joints was studied. Tensile shear load up to 4.65 kN was achieved by adjusting process parameters. The welding process and mode of the fracture were analyzed. The hybrid bonded joint obtained consisted of two parts: a welded joint of Al plate and Al rivet, and a bonded interface between Al plate and CFRP plate. The mechanical properties of the hybrid joint were mainly determined by the Al plate/Al rivet welded joint. The results of the study show that there are three interfacial bonding mechanisms between aluminum and CFRP. In addition to mechanical bonding between the Al plate and CFRP plate, there were also metallurgical bonding of Al-Mg intermetallic compounds with resin matrix and chemical reactions of aluminum with resin and carbon fibers at the interface, which could improve the mechanical properties of the joints.

Method of Designing a Friction-Based Wedge Anchorage System for High-Strength CFRP Plates

The cables of high-strength carbon fiber reinforced polymer (CFRP) plates are starting to be applied to large spatial structures. However, their main anchorage systems rely on the adhesive force, which entails risks to their integrity resulting from aging of the binding agent. In this study, a friction-based wedge anchorage system was designed for CFRP plates. The working mechanism of the proposed anchorage system was explored both theoretically and experimentally. The anti-slip mechanism and condition of CFRP plates were formulated so that the equivalent frictional angle of the contact surface between a CFRP plate and wedges must not be smaller than the sum of the dip angle of the wedge external conical surface and the frictional angle between the wedges and barrel. An analysis of the stress distribution in the anchorage zone of the CFRP plate was conducted using the Tsai-Wu failure criterion, which concluded that the compressive stresses should be reduced on the section closer to the load-bearing end of the anchorage system. Furthermore, the anchorage efficiency coefficient was proposed, which depends on stress concentration coefficients, plate thickness, length of anchorage zone, dip angle of wedge external conical surface, and its frictional angle. Then, it was determined that the minimum length of an anchorage zone for the CFRP plates with various specifications should be at least 49 times larger than the CFRP thickness. A finite element analysis and static tensile tests on six specimens were carried out. The experimental results revealed that the anchorage efficiency coefficient of the optimized anchor reached 97.9%.