고체역학 (Beer) — Pure Bending: Problem 4.157

4.157 (a) Show that the stress at corner A of the prismatic member shown in Fig. a will be zero if the vertical force P is applied at a point located on the line \[ \frac{x}{b/6} + \frac{z}{h/6} = 1 \] (b) Further show that, if no tensile stress is to occur in the member, the force P must be applied at a point located within the area bounded by the line found in part a and three similar lines corresponding to the condition of zero stress at B, C, and D, respectively. This area, shown in Fig. b, is known as the kern of the cross section.