The stress distribution in a bolted joint and the pressure distribution on the bearing surface of a nut have been examined by three-dimensional photoelastic experiment. As a result of this experiment: (1) The experiment shows that the stress distribution in a bolted joint has unaxially symmetric, since the screw part has an unaxi-symmetrical shape. (2) The pressure distribution on the bearing surface of a nut has an unaxial symmetry corresponding to that stated above. (3) It can be seen that the screw part of the bolted joint is acted upon by the bending moment due to the asymmetric pressure distribution.
