p. 121-132
Authors investigated the optimum configuration problem around a hole in an infinite elastic plate under the uniform loading in the previous report. Although two optimum configurations expressed by the mathematical descriptions for the given aspect ratio were proposed, there was a remaining problem that the value of the stress concentration factor could be decreased further a lower limit value. In this report, the fundamental property of the stress distribution around a hole is studied, it has been shown that the optimum stress distribution which have the minimum value of the stress concentration factor must be uniform in tension and compression stresses respectively. Authors propose the method of conformal mapping and the iteration method using the variational principle of the stress function to find the optimum configuration having that of stress distribution. As the result of investigation, the optimum configuration have a part which sticks out like an angle. The minimum value of the stress concentration factor for the given aspect ratio is shown and the standard of judgment for practical usage is determined