Hi,(adsbygoogle = window.adsbygoogle || []).push({});

Got to the last question in my mechanics problems list and just cant get it!

You have a brass tube with steel bar inside.

The brass tube is 400.12mm long; longer than the steel bar which is 400mm long.

You have to calculate the stress in both objects when a compression load of 60kN is applied.

I thought the first thing to do would be calculate how much force it required to shrink the brass tube down to the same length as the steel bar. Which is easy: F=stressxarea so F=16.488kN.

So now both materials are the same length so from this point on any change in length must be identical for both objects.

E is given as 100kN/mm2 for Brass and 200kN/mm2 for steel.

The area (cross sectional) of the brass tube is 550mm2 and 616mm2 for the steel bar.

At this point it all goes wrong! (I know what the answers are as they`re given but I cant get the right numbers....:grumpy: ).

I imagine its probably related to the fact the the change in lengths must be identical but how you apply that thinking has just irritated me.

Any ideas much appreciated!

Thanks

Calum

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# Homework Help: Stress problem

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