Spec yield and ult strengths - true or engineering stress?

Thread starter blue24
Start date Apr 25, 2015
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Engineering Stress Yield

In summary, there are two main types of stress: true stress and engineering stress. True stress takes into account the effect of deformation on a material, while engineering stress does not. Ultimate strength and yield strength are two measures of a material's strength, with ultimate strength being the maximum stress a material can withstand before breaking and yield strength being the maximum stress it can withstand before permanent deformation. True stress and engineering stress are calculated differently, with true stress taking into account the change in cross-sectional area due to deformation. Both measures are important in engineering applications, but engineering stress is more useful for comparison between materials and determining yield points, while true stress is more useful for understanding a material's behavior under extreme conditions.

Apr 25, 2015

blue24

Are the yield and ultimate strengths that you find in specs (e.g. ASTM A36) true stress or engineering stress values?

Thanks!

Andrew

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Apr 25, 2015

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blue24 said:

Are the yield and ultimate strengths that you find in specs (e.g. ASTM A36) true stress or engineering stress values?

Thanks!

Andrew

Engg stress.

1. What is the difference between true stress and engineering stress?

True stress is a measure of the actual applied force on a material, taking into account the change in cross-sectional area due to deformation. Engineering stress, on the other hand, is a measure of the applied force on the original cross-sectional area of the material. In other words, true stress takes into account the effect of deformation on the material, while engineering stress does not.

2. How is ultimate strength different from yield strength?

Ultimate strength is the maximum stress that a material can withstand before it breaks. It is a measure of the material's strength under extreme conditions. Yield strength, on the other hand, is the maximum stress that a material can withstand before it starts to deform plastically (permanently). It is a measure of the material's ability to return to its original shape after being subjected to stress.

3. Is true stress always higher than engineering stress?

No, this is not always the case. In some materials, the true stress may be lower than the engineering stress. This is because as the material deforms, its cross-sectional area decreases, leading to a decrease in the true stress. However, in most cases, the true stress is higher than the engineering stress.

4. How do we calculate true stress and engineering stress?

True stress is calculated by dividing the applied force by the actual cross-sectional area of the material at that point (taking into account the change in area due to deformation). Engineering stress is calculated by dividing the applied force by the original cross-sectional area of the material before deformation.

5. Which stress measure is more useful in engineering applications?

Both true stress and engineering stress are important in engineering applications. However, in most cases, engineering stress is more useful as it allows for easier comparison between different materials and makes it easier to determine the yield point of a material. True stress, on the other hand, is more useful in understanding the behavior of a material under extreme conditions.