Abstract
The paper describes the results of repeated stress bending tests to determine whether the resistance of welded plates to repeated stresses depends on the size of the plate, or in other words, if there is a “scale effect”; and to compare the results obtained from welded plates with those from plates with holes drilled in them. The tests were carried out in the bending machine‡ designed by one of the authors.
In the second§ and third‖ reports of the Welding Research Committee the results of repeated stress tests on 
-inch butt-welded plates and on 3-inch butt-welded plates had shown that from the smaller butt-welded plates a higher fatigue range from zero minimum stress had been obtained than from the 3-inch butt-welded plates. A detailed examination of the welds did not indicate a satisfactory explanation of the difference, and it appeared desirable, therefore, to make further tests on specimens of various thicknesses to determine whether the lower fatigue range was due to the size of the specimen.
The results given in the paper show that for specimens from 1 inch to 3 inches in thickness made in three different works no scale effect is indicated. The tests made on drilled plates confirm others previously carried out, and show that drilling a hole in a plate reduces the fatigue range load very considerably. The results from the thick welded plates show that with well-controlled welding, fatigue ranges for the welds as high as those from the black plate can be obtained.
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