An alloy of steel has a youngs modulus of 180gpa elastic...

An alloy of steel has a Young’s modulus of 180GPa, elastic limit of 0.002 and ultimate tensile strength of 860MPa. An alloy of aluminium has a Young’s modulus of 70GPa, elastic limit of 0.004 and ultimate tensile strength of 110MPa. a) Sketch a stress-strain graph for both of these alloys, plotting them on the same graph b) Label significant positions on the graphs c) Compare and contrast the mechanical properties of these alloys

Transcript

00:02 Hello, for this problem, we are given the properties of an alloy of steel and the properties of an alloy of aluminium.

00:11 We are told to draw this on the same graph, on a stress strain graph, and then compare their mechanical properties.

00:23 So here, i'll go ahead and plot my stress strain graph for these two materials.

00:33 This here is strain sigma, this is stress rather, and this is strain.

00:49 I'll use the red color for steel and i'll use another color for aluminium.

00:55 Now we were given the following properties that the young's modulus of steel is 180 giga -pascals.

01:10 We are told the elastic limit for steel is 0 .002.

01:17 The ultimate tensile strength for steel is 860 mp a we are also given properties for aluminum we are told that the youngest modulus of aluminum is 70 gigapascals we are told that its elastic limit is 0 .004 and that its ultimate tensile strength is 110 megapascals if i plot this sketch plot of this on this um stress string curve this the curve for steel will be something like this while that for aluminum will be something like this let us notice the following things now i'll start again for steel this here becomes this elastic limit the point where this stops being linear i'll just trace that down and that is 0 .002 while for aluminum this becomes the elastic limit where it stops being linear and i'll mark that as 0 .004 about two times that of steel and this point here is what we call the yield point.

03:07 I will label that there the yield point of steel and for aluminum this here becomes the yield point for the aluminum.

03:20 Again we can see the ultimate 10 size strength of steel is about 860 mp so i'll just trace that there this is about 860 mp while that for aluminum is about 110 mp when i trace that and this point is the fracture points for steel this is the fracture point let me call that f while this is the fracture point for aluminum one interesting thing here is let us look at the slow of the linear paths for steel and aluminum.

04:09 Steel has a higher slope in the linear region, what we call the elastic region than aluminum.

04:17 And the reason for that is simple.

04:19 The reason for that is because the youngs modulus of steel is higher than the youngs modulus of aluminum...

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