Why is the maximum y value different from the centroid?

In summary, the conversation discusses the sectional area of a beam under axial force and moments. The centroid and second moment of area around both axes have been found, and the individual is seeking to compute the maximum axial stress. The provided section can be found at the given link, and the correct answer was obtained by using Navier's formula. However, there is confusion regarding the values of ymax and zmax in the formula and how they relate to the results. The individual is advised to look at stress distribution diagrams for further clarification.
  • #1
kasse
384
1
I've got a sectional area of a beam that is subjected to an axial force N = -100 and momenst M(y) = -50 kNm and M(z)= - 120 kNm. I've found the centroid and the second moment of area around both axes.

How can I compute the maximum axial stress?

Here's the section: http://www.badongo.com/pic/624173


Edit:
I got the correct answer after trying Naviers formula several times:

Max stress = N/A + (M(z)*y(max))/I(z) + (M(y)*z(maks))/I(z)

What I don't understand is: Why is y(maks)=124 and not 151??
 
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  • #2
Well, if you got the correct answer, you should ask yourself what ymax and zmax represent in your formula and compare them with your results.
 
  • #3
Look at the stress distributions diagrams.
 

1. What is axial stress?

Axial stress is the internal force per unit area that is generated within a beam when it is subjected to an axial load or force. It is also known as direct stress or normal stress.

2. How is axial stress calculated?

Axial stress can be calculated by dividing the axial load or force by the cross-sectional area of the beam. The formula for axial stress is σ = F/A, where σ is the axial stress, F is the axial load, and A is the cross-sectional area.

3. What is the difference between axial stress and bending stress?

Axial stress is caused by a force that is applied along the length of the beam, while bending stress is caused by a force that is applied perpendicular to the length of the beam. Axial stress results in a change in length of the beam, while bending stress results in a change in shape or curvature of the beam.

4. How does axial stress affect the strength of a beam?

Axial stress can significantly impact the strength of a beam, as it can cause the beam to fail or deform if the stress exceeds the material's yield strength. It is important to consider both axial stress and bending stress when designing a beam to ensure it can withstand the expected load without failing.

5. What factors can affect the axial stress of a beam?

The axial stress of a beam can be affected by various factors, including the magnitude and direction of the applied load, the cross-sectional shape and size of the beam, and the material properties of the beam. Temperature changes, corrosion, and other environmental factors can also impact the axial stress of a beam.

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