The assembly shown consists of an aluminum shell ( Ea = 70 GPa, αa = 23.6 x 10-6/ºC ) fully bonded to a steel core ( Es = 200 GPa, αa = 11.7 x 10-6/ºC) and is unstressed at a temperature of 20 ºC. Considering only axial deformations, determine the stress in the aluminum shell when the temperature reaches 180 ºC.