# Stress/strain graph of copper past its elastic limit

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#1

Does the graph of D imply that the material can undergo elastic hysteresis, and therefore it is wrong because copper does not undergo elastic hysteresis? Or is B the answer because the graph of D curves a lot more than B, and therefore the strain wouldn't decrease when the stress is removed?
0
7 years ago
#2
(Original post by originaltitle)

Does the graph of D imply that the material can undergo elastic hysteresis, and therefore it is wrong because copper does not undergo elastic hysteresis? Or is B the answer because the graph of D curves a lot more than B, and therefore it wouldn't be able the strain wouldn't decrease when the stress is removed?
I believe that a hysteresis loop starts and ends at the origin like so:
http://www.diracdelta.co.uk/science/...s/image001.gif
0
6 years ago
#3
I think answer is A because stress-strain diagram is real function diagram i.e strain is independent variable and stress is dependent variable and in real valued functions independent variable gives only unique(i.e single value) value of dependent varialvle ,as in all three i.e B,C,D strain gives multiple values for single strain
0
6 years ago
#4
(Original post by priyanshmishra)
I think answer is A because stress-strain diagram is real function diagram i.e strain is independent variable and stress is dependent variable and in real valued functions independent variable gives only unique(i.e single value) value of dependent varialvle ,as in all three i.e B,C,D strain gives multiple values for single strain
Here's the textbook diagram:

If you remove the stress at C the material returns to O'

Which answer do you think is correct.
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3 years ago
#5
its B. A describes the energy required to stretch the wire. C cannot be the answer as the wire will want to unstretch back the way it did, so it will take the linear straight part. with D, it won't curve back once you have passed the elastic limit (limit of proportionality) of the wire. instead you can think of it as if the wire has a new youngs modulus. youngs modulus' are found by finding the gradient of the linear line of stress over strain. therefore when the wire is unstretching, it will take a linear path not a curved one- A.
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