4. Consider a stepped beam modeled using two beam elements. The cross-sections are circular.

Use Young's modulus E = 80GPa, yield stress ay = 250MPa, and L = 1 m. When F2 = F3 =

1,000N, calculate the minimum diameters of two sections so that the beam does not fail with safety margin of 100 MPa.

A y 1 2

^ ¦

2L L —s-