Solving Stress-Strain Curve: Ultimate Stress, Units Confirmation

In summary, the conversation revolves around creating a stress-strain curve for a soft aluminum alloy and finding the ultimate stress. The person has attached a screenshot of their graph and formulas. They are unsure about how to find the ultimate strength and ask for confirmation on their units. The expert summarizes that ultimate strength refers to the stress at fracture and confirms that the units are correct.
  • #1
aaronfue
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0

Homework Statement



I was creating a stress-strain curve for a soft aluminum alloy (as stated in problem) and was looking to find the ultimate stress and ensure my units were all okay.

I have attached a screenshot of my graph. And a separate screenshot with the formulas.

Homework Equations



E=σ/ε
σ=P/A
ε=δ/L0

The Attempt at a Solution


I think I have my graphs correct. I am aware of how to get the modulus of elasticity, yield strength, but the ultimate strength is confusing me on this one. It couldn't be the strength at fracture. How can I find it?

Also, if anyone could confirm that my units are set up correctly, I would greatly appreciate it.
 

Attachments

  • stress-strain1.JPG
    stress-strain1.JPG
    47.9 KB · Views: 439
  • stress-strain2.JPG
    stress-strain2.JPG
    49.8 KB · Views: 451
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  • #2
Ultimate strength means the stress at fracture. Once the sample fractures, it cannot support any more stress.

Your units look OK.
 
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1. What is the purpose of solving a stress-strain curve?

The purpose of solving a stress-strain curve is to determine the mechanical properties of a material, such as its ultimate stress and strain, which can help in designing and predicting the behavior of the material under different conditions.

2. What is ultimate stress and how is it calculated?

Ultimate stress is the maximum stress a material can withstand before it breaks or fails. It is typically calculated by dividing the maximum force applied to the material during a tensile test by the original cross-sectional area of the material.

3. What are the units used for ultimate stress?

The units for ultimate stress depend on the system of measurement being used. In the International System of Units (SI), ultimate stress is measured in megapascals (MPa). In the US Customary system, it is measured in pounds per square inch (psi).

4. Why is it important to confirm the units when solving a stress-strain curve?

Confirming the units is important because using the wrong units can lead to incorrect calculations and conclusions about the mechanical properties of the material. It is also important for comparing data from different sources and ensuring consistency in measurements.

5. Can the stress-strain curve be used for all types of materials?

The stress-strain curve can be used for most types of materials, including metals, plastics, and ceramics. However, it is important to note that different materials may have different types of stress-strain curves and may behave differently under different conditions.

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