Effect of printing parameters on the vibration behavior of an inverted slider-crank mechanism with flexible 3D-printed crank arms

This study investigates the effects of flexible crank arms manufactured with different additive manufacturing parameters—namely infill density, raster angle, and geometric thickness—on the vibration characteristics of an inverted slider–crank mechanism, and compares their performance with that of a rigid crank arm. An experimental setup was developed to measure vibration responses at the bearings of the inverted slider–crank mechanism. Initially, experiments were conducted using a rigid crank arm, and the resulting vibration data were recorded as a reference. Subsequently, 27 flexible crank arm specimens were produced with varying printing parameters, including raster angles of 45°, 90°, and 135°, infill densities of 50%, 75%, and 100%, and thicknesses of 26, 28, and 30 mm. Using the same experimental setup, the influence of these parameters on bearing vibration was experimentally investigated and compared with the rigid crank configuration. Finally, the experimental results were also compared with predictions from a rigid-body mechanism. The power spectral density (PSD) method was employed to evaluate and analyze the vibration responses. The results demonstrate that a flexible crank arm generally reduces the mechanism's vibration levels. However, excessive flexibility—particularly in specimens printed with a 50% infill density—led to significant shape deformation, adversely affecting the mechanism's dynamic behavior. Overall, the lowest vibration levels were achieved when the crank arm was manufactured with a 75% infill density, a 45° raster angle, and a thickness of 26 mm.