When manufacturing a square plate with a pinhole, the following conclusions were obtained as a result of analyzing the effect of changes in the size of the grid filling the inside of the plate and the presence or absence of a pinhole on the stress concentration factors. 1. It can be seen that in the case where there is a pinhole, the overall stress concentration factors is twice as high as in the case where there is no pinhole. In addition, in the case where there is no pinhole, it can be seen that the stress concentration factors fluctuates at a certain standard depending on the position of the pinhole and the internal grid, and in the case where there is a pinhole, it decreases at a certain point and then increases again. 2. In the case where there is no pinhole, when the L/H ratio increases from 0.1 to 0.3, the Kt value increases from 1.8 to 2.7, an increase rate of approximately 50%. Similarly, in the case of a pinhole, when the L/H ratio increases from 0.1 to 0.4, the Kt value increases from 2.0 to 3.0, an increase rate of about 50%.

In this study, when manufacturing a rectangular plate with a pinhole, the following conclusions were obtained as a result of analyzing the shape characteristics of the unit cell that fills the interior of the plate and the effect of changes in the size of the pinhole on the stress concentration coefficient. 1. The stress value generated in the case of the completely empty model was 13.9 MPa, which is an 18.8% increase in stress compared to the stress value 11.7 MPa generated in the fully filled model. However, since the weight of the empty model is 43.6% lower than that of the filled model, it is believed to be very advantageous in terms of cost. 2. The stress concentration coefficient value is lowest for the solid model and highest for the hollow model at the same d/H value. In other words, you can see that the values are changing within the boxes of the solid model and hollow model. However, the grid matching model is closest to the solid model and the filling rate is as low as 33.4-9.1%, showing the most stable strength when filling empty space.