Effects of notch's position along a rod that is in tension

In summary, the positioning of a notch on a rod will have a significant impact on the stress concentration, with a notch at the middle of the rod having a greater effect than a notch at the end. This stress concentration can lead to cracking and a decrease in rod strength, especially under fatigue loads. However, the exact effect of the notch position is difficult to analyze and is dependent on various factors such as the cross section and depth of the notch. For a static analysis, the notch position only becomes important when there is a side force or a misalignment of end attachments. Dynamic analysis, such as for a spinning shaft, will be more complex. Further research and information can be found on the effects of notches from sources such as the University
  • #1
yonese
15
1
Say I have a rod with a notch at the very centre and another ro with a notch at the very end. Both rods are identical in length radius materials etc. Who would be impacted by the notch more? And if then both were to support a load at the end of the rod (both in tension), what effects would the load have on the stress concentration caused by the noth? Obviously any cracks under fatigue loads will significantly reduce the rod strength, but how does the effect positioning of a notch vary?

I understand a notch causes a stress concentration that typically leads to local plastic strain which eventually leads to cracking. I'm certain that the positioning of a notch will affect the stress concentration, I just don't know how. I am also guessing that a notch at the middle of the rod will have more significant effect than a notch at the end.
 
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  • #2
yonese said:
I'm certain that the positioning of a notch will affect the stress concentration, I just don't know how.
For a static analysis, the position of the notch will only become important when there is a side force or a misalignment of the end attachments.
The dynamic analysis of a spinning shaft with a notch, will be more complex.
 
  • Informative
Likes berkeman
  • #3
See diagram.

Simplistically (because it is a very non-linear problem):

The average stress at B is P/Area B
The average stress at A is P/Area A, which is higher

The stress will therefore fall as you move away from the notch. The rate and shape of fall will be dependent on the bar cross section shape, the notch shape and notch depth and is difficult to analyse simply.

As long the bar is longer than the area where the stress is varying (and assuming you are loading the entire end faces uniformly) the length of the bar is irrelevant. If it isn't, it isn't.

There is a stress concentration at the tip of the notch.

Google for lots of information - eg NOTCHES AND THEIR EFFECTS from the University of Toledo.

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1. What is the purpose of studying the effects of notch's position along a rod in tension?

The purpose of this study is to understand how the position of a notch on a rod that is under tension affects its overall strength and ability to withstand stress and load. This information can be useful in engineering and design applications, as well as in predicting the failure of materials under tension.

2. How does the position of the notch affect the strength of the rod?

The position of the notch can significantly impact the strength of the rod. Placing the notch at a point of high stress concentration can weaken the rod and increase the chances of failure. However, placing the notch at a point of low stress concentration can have minimal effect on the strength of the rod.

3. Is there an optimal position for the notch along the rod?

There is no one optimal position for the notch along the rod. The best position depends on the specific application and the desired strength and performance of the rod. It is important to consider the stress distribution along the rod and place the notch in a location that minimizes stress concentration.

4. How does the material of the rod affect the effects of notch's position?

The material of the rod can greatly influence the effects of notch's position. Different materials have varying strengths and stress distribution patterns, which can impact the position of the notch. For example, a brittle material may be more susceptible to failure at the notch than a ductile material.

5. What other factors should be considered when studying the effects of notch's position along a rod in tension?

In addition to the position of the notch and the material of the rod, other factors that should be considered include the size and shape of the notch, the type of loading (tension, compression, bending), and the environmental conditions (temperature, humidity, etc.). These factors can all play a role in the overall strength and performance of the rod.

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