A filleted plate of thickness t supports an axial load P. Determine the radius r of the fillet so that the same stress occurs at the hole and the fillets. Assume the plate is made of a relatively brittle metallic alloy. Use tables for finding the stress concentration factors provided at the end of the document.
Given: P = 50 kN, D = 100 mm, df = 66 mm, dn = 20 mm, t = 10 mm.