3371088
Badges: 5
Rep:
?
#1
Report Thread starter 2 years ago
#1
This is taken from last years unit 2 paper:
Why is the yield point at B and not C? Isn't the yield point the stress or force at which a large amount of plastic deformation takes place with constant or reduced load? On the graph, extension increases for a decrease in force at C, so why is B the yield point?

Name:  Untitled.png
Views: 110
Size:  44.3 KB
0
reply
anissabir95
Badges: 9
Rep:
?
#2
Report 2 years ago
#2
C is the Ultimate Tensile Stress. - strongest point of wire.
0
reply
3371088
Badges: 5
Rep:
?
#3
Report Thread starter 2 years ago
#3
(Original post by anissabir95)
C is the Ultimate Tensile Stress. - strongest point of wire.
But doesn't C also meet the criteria to be the yield point?
And what makes B the yield point?
0
reply
Gerry-Atricks
Badges: 22
Rep:
?
#4
Report 2 years ago
#4
B is the yield point, C is the UTS, you get some molecular rearrangement after yield point which lowers youngs modulus at that point but after UTS material is breaking so also some molecular reshuffle there. In general the little hump after the elastic limit is the yield point
0
reply
3371088
Badges: 5
Rep:
?
#5
Report Thread starter 2 years ago
#5
(Original post by glad-he-ate-her)
B is the yield point, C is the UTS, you get some molecular rearrangement after yield point which lowers youngs modulus at that point but after UTS material is breaking so also some molecular reshuffle there. In general the little hump after the elastic limit is the yield point
what from the graph made you identify B as the yield point? Just the fact that it comes after the elastic limit? Is that the only indication from the graph?
0
reply
Gerry-Atricks
Badges: 22
Rep:
?
#6
Report 2 years ago
#6
(Original post by exams292)
what from the graph made you identify B as the yield point? Just the fact that it comes after the elastic limit? Is that the only indication from the graph?
That the gradient of the graph has a slight dip add to that the fact that it's not the maximum of the graph suggests it must be the yield point
1
reply
3371088
Badges: 5
Rep:
?
#7
Report Thread starter 2 years ago
#7
(Original post by glad-he-ate-her)
That the gradient of the graph has a slight dip add to that the fact that it's not the maximum of the graph suggests it must be the yield point
Thanks! One last thing. Can the yield point and UTS point ever coincide?
0
reply
Gerry-Atricks
Badges: 22
Rep:
?
#8
Report 2 years ago
#8
(Original post by exams292)
Thanks! One last thing. Can the yield point and UTS point ever coincide?
No-as far as I know
0
reply
3371088
Badges: 5
Rep:
?
#9
Report Thread starter 2 years ago
#9
(Original post by glad-he-ate-her)
No-as far as I know
Ok, thanks, good luck on Wednesday
0
reply
Gerry-Atricks
Badges: 22
Rep:
?
#10
Report 2 years ago
#10
(Original post by exams292)
Ok, thanks, good luck on Wednesday
Thank you
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of East Anglia
    PGCE Open day Postgraduate
    Tue, 3 Mar '20
  • University of Bradford
    Postgraduate Open day/Evening Postgraduate
    Tue, 3 Mar '20
  • Queen's University Belfast
    Postgraduate LIVE Masters & PhD Study Fair Postgraduate
    Wed, 4 Mar '20

Do you get study leave?

Yes- I like it (498)
59.71%
Yes- I don't like it (43)
5.16%
No- I want it (237)
28.42%
No- I don't want it (56)
6.71%

Watched Threads

View All