Difference between actual and visual rupture point?

Replies

• 

  CE Designer

  Do you mean true vs. engineering stress points?
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  Ammar Aziz

  yes certainly! i am talking about true and engineering stress point. but what is the relation between actual and visual rupture point with true and engineering stress points.
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  CE Designer

  I am not certain, I have honestly never come across the terms actual and visual rupture point.
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  Ammar Aziz

  here is the picture attached so although from figure the actual and visual rupture point or true and engineering stress point are in same vertical line then what does it shoes?
• 

  CE Designer

  OK Point 3 on the red graph is called the Engineering Stress (Visual) point.
  When the graph peaks at the Ultimate Tensile strength necking begins soon after. When necking sets in the cross-sectional area of the specimen is shrinking. The load bearing capacity is therefore reducing. This means that the force required to further strain the specimen is smaller.
  
  Engineering Stress is calculated using the applied load divided by the original cross sectional area of the specimen (not the cross-sectional area of the necking region). So the Force required to strain is decreasing and the area is remaining the same (Stress = Force/Area) This is why the graph dips.
  
  However the Actual Stress should be calculated using the instantaneous cross-sectional area , not the original. Since the area is decreasing the actual/true stress will be higher as shown at point 3 on the blue graph.
  
  I Hope this helps you.
• 

  Ammar Aziz

  thank you very much. now i got the clear concept.