Numerical and experimental study on friction connections performance-asymmetric and symmetric (AFC/SFC)
This paper presents experimental test results and a finite element model validation of Asymmetric Friction Connections (AFC) and Symmetric Friction Connections (SFC) under a quasi-static cyclic sliding displacement regime. The experimental tests were conducted using M24 bolts. The numerical simulation of friction connections was developed using the finite element software ABAQUS. It was shown that the AFC and SFC hysteresis shapes are almost rectangular with the significant differences in the magnitude of strength, bolt force reduction during the sliding, damage severity and wear mechanism and reparability. Calibrated finite element model results were in good agreement with the experimental results under cyclic quasi-static loading regime. The numerical stress distribution, equivalent plastic strain, and the bolt force obtained at different sliding displacements were validated with the experimental tests. Effective friction coefficient varied between 0.14 to 0.18 for the AFC with wire brushed surfaces and 0.40 to 0.48 for the SFC with a similar configuration and preparation. The maximum strength reached 410 kN and 125 kN during the second run for the SFC and the AFC respectively. The wear mechanism and damage severity regarding volume and geometry of loose wear particles and formed grooves are higher in the SFC due to the higher friction coefficient as a result of different frictional behaviour in sliding surfaces. The loss of pretension force for the AFC reached 45% after 5250 mm cumulative travel, and it was 9.0% for the SFC. The maximum strength degradation reached 15% and 20% for the SFC and the AFC respectively. Both AFC and SFC are reparable connections. After replacing bolts and/or shims both configurations gave almost stable hysteresis behaviour to 13125 mm cumulative travel.