Two bars are unstressed and have lengths of $$25cm$$ and $$30cm$$ at $$20$$° as shown in Figure. Bar (1) is of aluminium and bar (2) is of steel. The $$cross-sectional$$ area of bars are $$20cm2$$ for aluminium and $$10cm2$$ for steel. Assuming that the top and bottom supports are rigid, stress in Al and steel bars in $$Nmm2$$ when the temperature is $$700C$$. (Nearly$$ $$) $$Ya=0.70$$×$$105N/mm2$$⋅$$Ys=2.1$$×$$105N/mm2$$α$$a=24$$×$$10$$−$$6/$$∘C and α$$s=12$$.×$$10$$−$$6/$$∘C

Question

Two bars are unstressed and have lengths of $$25cm$$ and $$30cm$$ at $$20$$° as shown in Figure. Bar (1) is of aluminium and bar (2) is of steel. The $$cross-sectional$$ area of bars are $$20cm2$$ for aluminium and $$10cm2$$ for steel. Assuming that the top and bottom supports are rigid, stress in Al and steel bars in $$Nmm2$$ when the temperature is $$700C$$. (Nearly$$ $$) $$Ya=0.70$$×$$105N/mm2$$⋅$$Ys=2.1$$×$$105N/mm2$$α$$a=24$$×$$10$$−$$6/$$∘C and α$$s=12$$.×$$10$$−$$6/$$∘C

Infinity Learn · Accepted Answer

Contraction of the two bars due to compressive stress $$=$$ Elongation of the two bars due to rise of temperature $$SlYAl+SlYSt=($$αAlLAlΔ$$t)Al+($$αStLsΔ$$t)StForce$$ in steel $$=$$ force in aluminiumSAl×$$AAl=SSt$$×ASt

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