Stresses and deformations in overlapped diesel engine crankshafts - Part 1: experimental results

Single-throw, epoxy resin models of five overlapped crankshafts with side-by-side connecting rods have been loaded in pure torsion or bending. Bending loads considered are those due to the radial or tangential components of the connecting rod force and those due to pure radial bending or radial bending due to journal displacement. After the photoelastic frozen-stress cycle, deformations and stresses in the crankpin and journal fillets were measured. The principal stresses were determined over the whole highly stressed (toroidal) fillet surfaces. At each angular position around the crankpin and journal the magnitude, meridional position and direction of the greatest principal stress were obtained. In torsion these maxima were fairly constant with angular position, whereas in bending they varied linearly, as in a simple beam in bending. The results were expressed as stress concentration factors based on nominal stresses in a bar of the same diameter as the crankpin.