An infinite 6061-T6 aluminum alloy beam of b X b square cross section resting on an...

An infinite 6061-T6 aluminum alloy beam of b X b square cross section resting on an elastic foundation of k carries a concentrated load P at its center (Fig. 9.2). Using a factor of safety of n with respect to yielding of the beam, compute the allowable value of b. Given: E = 70 GPa, = 260 MPa (Table D.1), k = 7 MPa, P = 50 kN, and n = 1.8