Understanding Principle Stresses: Calculating X & Y Stress

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In summary, the conversation discusses the concept of principle stresses and how to calculate the stress in the x and y directions. The speaker suggests drawing a free body diagram and practicing intuition to determine the loads needed. They also recommend reading a book on elasticity theory and offer to send a helpful example through email.
  • #1
2slowtogofast
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I need some help understanding principle stresses.
I understand the formula i have problems calculating the stress in x and the stress in y to plug into the formula. More simply how do i know what contributes to the stress in x and the stress in y for a given problem.
 
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  • #2
The first thing you should do is to draw a free body diagram of an element in the area you are interested in. The loads imposed will affect that FBD. That is what tells you what you need. Granted, there is a certain amount of practice and intuition involved as well.
 
  • #3
It's called elasticity theory. Try reading a book.
 
  • #4
Brian_C said:
It's called elasticity theory. Try reading a book.

Oh, come on, Brian. He has a legitimate question and your reply was a bit harsh.

To answer your question, there are several steps you'll need to go through. Send me private message with your email address and I'll send you a .pdf of a good example. Good luck!
 

1. What are principle stresses?

Principle stresses are the maximum and minimum stress values experienced by a material or structure at a specific point. They are important in understanding the behavior and failure of materials under different loading conditions.

2. How are principle stresses calculated?

Principle stresses can be calculated using the equations σ1 = (σx + σy) / 2 ± √[(σx - σy)^2 / 4 + τxy^2] where σ1 is the maximum principle stress, σx and σy are the normal stresses in the x and y directions, and τxy is the shear stress.

3. What is the significance of calculating X and Y stress?

Calculating X and Y stress allows us to determine the principle stresses and understand how a material or structure will respond to different loading conditions. This information is crucial in designing and analyzing structures to ensure their safety and efficiency.

4. How can principle stresses be used in material selection?

The knowledge of principle stresses can help in choosing the right material for a specific application. Materials with high strength and stiffness are suitable for structures experiencing high principle stresses, while materials with high ductility and toughness are better for structures experiencing high shear stresses.

5. Are there any limitations to the principle stress calculations?

Yes, principle stress calculations assume that the material or structure behaves in a linear elastic manner. This means that the stress-strain relationship follows Hooke's law, and the material does not undergo any permanent deformation. In reality, materials may exhibit non-linear behavior and undergo plastic deformation, which can affect the accuracy of the calculations.

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