A steel bar ABCD consists of three sections: AB is 30mm diameter and 300mm long, BC has a square cross section 35 mm on a side and is 400mm long and CD has a diameter of 15mm and is 100mm long. The sections have a common axis along the length of the bar. The bar is subjected to an axial compressive load which induces a stress of 40 MPa on the region of the largest cross section. Determine the change in length of the bar.

E= 210 GPa

v = 0.30

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