Effect of CF/PEEK plasticity behavior on the mechanical performance of interference‐fit joint

Abstract

Carbon fiber reinforced polyetheretherketone polymer (CF/PEEK) thermoplastic composites have a marked plastic yield stage compared to thermoset composites with epoxy matrix. During the interference fit riveting process, extrusion between rivet and composites laminate creates plastic deformation on the hole wall, which will enhance the bearing capacity of composites hole. Therefore, it is expected that the interference fit will play a greater advantage in enhancing the bearing strength of CF/PEEK riveted joint. Numerical and experimental study are applied to investigate the effect of interference fit on bearing strength of CF/PEEK riveted joint. Results show that the plastic deformation of CF/PEEK composites hole wall is positively correlated with the bearing strength of CF/PEEK riveted joint. When the interference fit size exceeds 2.6%, the bearing capacity of CF/PEEK riveted joint reduces because of the increase of fiber damage. It is concluded that the plastic deformation of riveted hole wall can enhance the bearing capacity of CF/PEEK riveted joint, while fiber damage reduces the bearing capacity of CF/PEEK riveted joint. As the increase of interference-fit size, bearing strength of CF/PEEK riveted joint raises first then decreases, the appropriate interference-fit size is in the range of 2.0%~2.6%, which is larger than that of thermoset composites.

Tests and Numerical Study of Single-Lap Thermoplastic Composite Joints Bolted by Countersunk

“…Experimental results have proved that thermoplastic composites do not have a well-defined yield point [ 39 ]. For this reason, the yield stress is always assumed to be 0 in many works [ 28 , 42 , 43 , 44 , 45 ]. An isotropic hardening function expressed by the equivalent plastic strain was adopted in this study: where and are determined by fitting the experimental hardening curve.…”

“…With the development of technology, thermoplastic composite materials have been increasingly used in modern industry and thermoplastic joints, such as pinned joints [ 7 ], riveted joints [ 26 , 27 , 28 ], and protruding bolted joints [ 29 , 30 , 31 , 32 ], have already been focused on. Yýlmaz and Sýnmazçelik [ 7 ] carried out experimental methods to investigate the bearing performance of the pinned joints of carbon fiber/polyphenylene sulfide (CF/PPS).…”

“…They found that the domed head rivet achieved higher fatigue limit strength at 2 × 10 6 cycles and higher bearing strength at static loading than that of the countersunk rivet and the failure mode under the fatigue load was determined by the load amplitude and the joint geometry. The influence of interference fit on the bearing strength of a carbon fiber/polyetheretherketone (CF/PEEK) riveted joint was investigated by Yao et al [ 28 ] using both experimental and numerical approaches. According to their research, the extrusion between the rivet and the composite laminate created a plastic deformation on the hole wall, which would enhance the bearing capacity of the composite laminate; the acceptable interference-fit size was in the range of 2.0–2.6% for the CF/PEEK riveted joint.…”

Process parameter–mechanical property relationships and influence mechanism of advanced CFF/PEEK thermoplastic composites

“…[7] Carbon fiber reinforced polyether ketone (CF/PEEK) composites, as an outstanding representative of advanced thermoplastic composites, are considered to be the most promising and fastestgrowing engineering materials, due to the extremely high toughness and high environmental resistance (heat resistance and corrosion resistance) of PEEK. [8][9][10][11] However, due to the high melting point and high melt viscosity of PEEK resin, how to disperse the molten PEEK resin in the CF bundles as uniformly as possible and achieve sufficient impregnation of the CF bundles is a major challenge in the molding process. [12,13] And importantly, the molding process is the key process to make raw materials into the required products, and its process parameters has an remarkable impact on the forming quality and comprehensive mechanical properties.…”

Tribological Characterization of Polyether Ether Ketone (PEEK) Polymers Produced by Additive Manufacturing for Hydrodynamic Bearing Application

“…The addition of small amounts of reinforcements, such as carbon fiber [22,23] and solid lubricants such as PTFE and graphite, improves both the mechanical and the tribological properties of PEEK polymers [24,25]. The heat treatment increases the hardness capacity and tensile strength of PEEK-based polymers [26].…”