抄録
In this study, the stress concentration factors of a slotted curved beam subjected to uniform bending are reported.
The experiment was carried out by the photoelastic method. Epoxy resin plates with thickness of 6mm were used as specimens, and a uniform bending moment was applied. The width of the curved beam and the length of the slot were maintained as constant. The radius of the curvature was varied in four steps (including the case of a straight beam) and the radius of semi-circle at both ends of the slot, and also the eccentricity of the slot from the center line of the beam were changed in three ways, respectively.
The stress concentrations along the upper and lower edges, through the minimum cross section and around the slot were examined, and the stress concentration factors at four main points were measured for several cases of the test conditions mentioned above. Moreover, the ratio of stress of the curved beam to that of the straight beam at each corresponding point was also investigated.
From the experimental results, the following conclusion has been made.
(1) The s.c.f. at the upper or lower edge of the beam decreases or increases, respectively, with the increase of curvature. But the s.c.f. at the upper or lower end of the slot shows an inverse tendency to that at the edge. As to the effect of eccentricity, the approach of the slot to each edge raises the s.c.f. at the edge. This trend is identical for the s.c.f. at the upper or lower end of the slot, when the slot approaches the upper or lower edge, respectively. The maximum values of s.c.f. obtained in this experiment are 1.4 and 1.8, respectively, for the lower edge of the beam and for the upper end of the slot.
(2) The ratio of stress of the curved beam to that of the straight beam is more than unity at the lower edge of the beam as well as at the upper end of the slot in all cases. This fact confines our attention to these points.
(3) In order to secure that none of the stresses at several main points of the slotted curved beam become specially large, it is desirable to locate the slot on the centre line of the beam, avoiding the eccentricity of the slot.
