On the Stiffening of the Edge of the Hole in an Orthogonally Aeolotropic Plate with a Circular Hole : Continuation-Stiffened with a Flanged Coaming Plate and with the Double Stiffening Plates

As a means of reducing the circumferential stress concentration in a plate, in the preceding report, we took up the case of stiffening with a coaming plate around the edge of the hole to supplement the doubling plates. Further, to reduce such concentration of stress, stiffening flanges are attached on the coaming plate or double stiffening plates are used. This paper deals with the effect produced by the coaming plate having the stiffening flanges (namely, the flanged coaming plate), and the effect produced by the double stiffening plates on the stress distribution in an orthogonally aeolotropic plate under uniform tension. In the case of the flanged coaming plate, the circumferential stress around the edge of the hole dcreases in proportion to the increase of the area of the cross section of the stiffening flanges. But, if the stiffening flanges are not attached within an effective distance from the plate within the distance of about five times of plate thickness, there is hardly any reduction of the circumferential stress concentration, even if large stiffening flanges are used. Next, in the case of the double stiffening plates, we assume that the displacements are zero at the junction of the base plate and the coaming plate. Thus, the use of the double stiffening plates is the most effective of the various methods for reducing the circumferential stress concentration.