Stress Concentration and Fatigue Strength of Notched Specimens Under Repeated Bending Moment : (4th Report.) Hollow Cylinder with a Diametral Hole. Part. 1

When a solid circular bar with a diametrally penetrated circular hole is bent by the bending moment applied at the remote section from the hole, the greatest stress occurs on the periphery of the hole. As to this subject T.Ishibashi. discussed theoretically and calculated the form-factor. To obtain easily the equivalent values of the form-factor of this notched bar, we assumed two dimensionally stressed semicircular notched plate under the bending moment in the plane of the plate, and caluculated this form-factor or the stress concentration by our experimental formula, and then treating in the same way for another forms of the hole, rectangle, ellipse, etc., we have adopted as the equivalent values of these form-factors. The adopted values from the equation are satisfactory to be used as equivalent values of the form-factor for the circular or the hollow shafts with above mentioned diametral holes as compared with our experimental results of the large type thin cylinders. As our fatigue experiments shows, the failure occurs at the point of the maximum stress concentration on the periphery of the hole and spread into the circumferential direction, the form factor is very important for the determination of the hole-shape.