Problem 1.1: Two solid cylindrical rods AB and BC are welded together at B and loaded as shown. Knowing that d1 = 30 mm and d2 = 50 mm, find the average normal stress at the midsection of (a) rod AB, (b) rod BC. Problem 1.7: Each of the four vertical links has an 8 × 36-mm uniform rectangular cross section, and each of the four pins has a 16-mm diameter. Determine the maximum value of the average normal stress in the links connecting (a) points B and D, (b) points C and E. Problem 1.13: An aircraft tow bar is positioned by means of a single hydraulic cylinder connected by a 25-mm-diameter steel rod to two identical arm-and-wheel units DEF. The mass of the entire tow bar is 200 kg, and its center of gravity is located at G. For the position shown, determine the normal stress in the rod. Problem 1.36: A steel pipe of 400-mm outer diameter is fabricated from 10-mm thick plate by welding along a helix that forms an angle of 20° with a plane perpendicular to the axis of the pipe. Knowing that the maximum allowable normal and shearing stresses in the directions respectively normal and tangential to the weld are σ = 60 MPa and τ = 36 MPa, determine the magnitude P of the largest axial force that can be applied to the pipe.