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It is required to design the screw of a screw-jack by buckling consideration. One end of the screw is fixed in the nut and the other end supports a load of 20 kN. The length of the screw between the fi xed and free ends is 500 mm, when the load is completely raised. The screw is made of steel 40C8 (Syt = 380 N/mm2 and E= 207 000 N/mm2). Assuming a factor of safety of 2.5, determine the core diameter of the screw. It is required to design the screw of a screw-jack by buckling consideration. One end of the screw is fixed in the nut and the other end supports a load of 20 kN. The length of the screw between the fi xed and free ends is 500 mm, when the load is completely raised. The screw is made of steel 40C8 (Syt = 380 N/mm2 and E= 207 000 N/mm2). Assuming a factor of safety of 2.5, determine the core diameter of the screw