STRESS-DISTRIBUTION IN GUDGEON PINS

Frozen stress photoelastic tests were carried out on four shapes of gu dgeon pins, loaded in a piston of realistic shape by a realistic conne cting rod. The results showed that the greatest stresses occurred in t he gaps between the piston and connecting rod at the horizontal positi on in the bore. Measured compressive hoop stresses and calculated shea r stresses there were up to 21/2 times the mean shear stress. Thick ri ng calculations slightly overpredicted the compressive stresses and th e tensile hoop stresses at the vertical position, i.e. they are 'safe' . The greatest axial stresses were smaller than the above. Measured pi n deflections between the piston bosses were less than the results of simple beam calculations, which ignored the restraints exerted by the piston. Ovalization of the cross-section was largest in the middle.