The beam is made of a polyester that has the stress- strain curve shown, if the curve can...

The beam is made of a polyester that has the stress- strain curve shown, if the curve can be represented by the equation σ = [20 tan-1(15€)] ksi, where tan-1(15€) is in radians, determine the magnitude of the force P that can he applied to the beam without causing the maximum strain in its fibers at the critical section to exceed ϵ max = 0.003 in./in.