Enhanced design approach for keyed connections considering shaft keyway deformation

Abstract Keyed connections (KC) are among the most common types of shaft-hub connections (SHC) due to their simplicity in assembly and disassembly. However, the current design standard DIN 6892 limits torque transmission based on critical surface pressure, which may underestimate performance because it neglects the complex interaction between material properties, geometry, and loading conditions. This study introduces a new design criterion based on the related critical plastic deformation at the shaft notch, allowing a more accurate assessment of torque transmission, particularly for low-strength ductile steels where surface pressure exceedance is the predominant failure mode. Numerical simulations using ABAQUS and experimental tests on a hydraulic torque bench were carried out for KC made of C45+N and 42CrMoS4+QT steels. Comparison with DIN 6892 Method B shows that the proposed criterion better represents the actual transmission capacity and accounts for variations in shaft diameter. This approach enables more efficient use of material strength and supports resource-efficient SHC design.