I have this real graphic from a tensile test

In summary, the conversation discusses calculating the ultimate stress in relation to a stress versus deformation graph. The speaker mentions having a real graphic with two deformations and one stress, and explains that the orange curve represents stress versus unit deformation 1, the gray curve represents stress versus deformation 2, and the blue curve represents the average between the two deformations. The speaker seeks to calculate the fracture stress, which they believe is in the red rectangle, but acknowledges that the graphic in the last part seems illogical. The other speaker offers their opinion, stating that the red rectangles may not be the fracture stresses and suggesting that the increased load measured could be due to the testing machine rebounding. They also point out that the blue curve does not appear
  • #1
Queren Suriano
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Homework Statement


How can I calculate the ultimate stress? (I refere to the stress that it's in the green rectangle). I have a real graphic, I have two deformations, (it was 2 test, from the same material) and only one stress. The orange curve is Stress versus unit deformation 1, and the gray one is stress vs. deformation 2 . The blue one is the average between the deformation 1 and 2 vs Stress. The REAL graphic from I want calculate this, it's in the last part of the post

upload_2015-4-29_9-34-26.png


Homework Equations



[/B]

The Attempt at a Solution



I know that fracture stress is in the red rectangle. I know that the graphic in the last part of the curves, it's illogic (because the deformation "decrease") but the stress is ok, because is the real fracture stress

upload_2015-4-29_9-36-9.png
[/B]
 
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  • #2
I don't think the red rectangles are the fracture stresses. When the specimens failed the testing machine probably rebounded and since the machine is most likely calibrated using a strain gauge it gave you some negative displacement values. Not sure why an increased load was measured but I would be attempted to ignore these values.

Also the blue curve does not look like the average of the two curves to me.
 
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  • #3
Thank you for your opinion
 

Related to I have this real graphic from a tensile test

1. What is a tensile test?

A tensile test, also known as a tension test, is a type of mechanical test used to determine the strength and ductility of a material. It involves stretching a sample of the material until it breaks while measuring the applied force and the elongation of the sample.

2. Why is a tensile test important?

A tensile test is important because it provides valuable information about the mechanical properties of a material, such as its yield strength, ultimate tensile strength, and elongation. This information is crucial for designing and selecting materials for various applications.

3. How is a tensile test performed?

In a tensile test, a sample of the material is placed in a testing machine and subjected to a gradually increasing tensile force until it breaks. The force and elongation data are recorded to create a stress-strain curve, which can be used to determine the material's properties.

4. What does a real graphic from a tensile test show?

A real graphic from a tensile test shows the relationship between stress and strain for a particular material. It typically includes a linear elastic region, a yield point, and a plastic region, and can also show the material's ultimate tensile strength and fracture point.

5. How is a tensile test different from other mechanical tests?

A tensile test is different from other mechanical tests, such as compression or bending tests, because it specifically measures a material's response to tensile forces. This makes it particularly useful for materials that are used in applications where they will experience tension, such as in structural components or in the production of textiles.

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