Finding yield stress with only modulus of elasticity and Poisson's ratio?

In summary, the conversation is centered around finding the yield stress of a material using only the given properties of modulus of elasticity and Poisson's ratio. The problem involves calculating the minimum amount of aluminum needed to support a block at a certain height, but the yield stress value is unknown. Various equations and methods are discussed, but the solution ultimately depends on knowing the yield stress.
  • #1
leoflc
56
0
Is it possible to find the yield stress of a material with only modulus of elasticity and Poisson's ratio?

I was given a problem that:
What is the min. aluminum needed to support a block (10 Newton) to 1 meter high? E=70GPa and v=0.3 are the only given aluminum properties.

I would know how to solve it if I knew the yield stress.
Can anyone give me some help?

(I know the yield stress for Al is usually around 270-275, but let's pretend we don't know that).

Thanks a lot!
Leo

-----------------------------------
This is what I have so far:
use Hooke's Law for strain x, y, and z.
stress x = stress z = 0; stress y is in the vertical direction.
strain x = strain z = (-v*stress_y)/E

and I'm stuck...

Thanks.
 
Last edited:
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  • #2
I would use Area=(PL)/(Epsilon*E)

Hope that helps
 
  • #3
EQ said:
I would use Area=(PL)/(Epsilon*E)

Hope that helps

Thanks for the reply.
I might be missing something, but I don't know how to get the strain "Epsilon".
 
  • #4
What application is the problem centered around? A beam? A column? The way you have things worded here it's impossible to help you with your question.
 

1. What is yield stress?

Yield stress is the amount of stress that a material can withstand before it begins to deform permanently. It is an important parameter in determining the strength and mechanical properties of a material.

2. Can yield stress be determined with only modulus of elasticity and Poisson's ratio?

Yes, yield stress can be estimated with only the modulus of elasticity and Poisson's ratio using the following formula: Yield stress = (Modulus of elasticity * Poisson's ratio) / (1 + Poisson's ratio)

3. How accurate is the estimation of yield stress with only modulus of elasticity and Poisson's ratio?

The estimation of yield stress using only modulus of elasticity and Poisson's ratio is not as accurate as using other methods, such as conducting a tensile test. However, it can provide a reasonable estimate for initial design purposes.

4. What are the limitations of using only modulus of elasticity and Poisson's ratio to determine yield stress?

Using only modulus of elasticity and Poisson's ratio to determine yield stress does not take into account the effects of factors such as material microstructure, temperature, and loading rate, which can all influence the yield stress of a material. Therefore, the estimation may not be accurate for all scenarios.

5. Are there any other methods to determine yield stress?

Yes, there are other methods to determine yield stress, such as conducting a tensile test, performing hardness tests, or using stress-strain curves. These methods provide more accurate and reliable results, but may require more time and resources compared to the estimation using only modulus of elasticity and Poisson's ratio.

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