Computing Lateral Deflection of a Shaft: A Step-by-Step Guide

In summary, if you do not have the moment function, you will need to integrate the E*I*y'' ODE to compute the deflection.
  • #1
Ballena Joseph
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How do I compute the horizontal and vertical lateral deflection of the shaft?
 
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  • #2
Google "lateral deflection of shaft". This PDF on shaft design from the University of Northern Illinois looks like a good starting point.
 
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  • #3
You don't compute the deflections until you know the loading, as a general rule. What loads the shaft in your case of interest?
 
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  • #4
Dr.D said:
You don't compute the deflections until you know the loading, as a general rule. What loads the shaft in your case of interest?
I have computed loads from shear and moment diagram.
 
  • #5
If you have the moment function, then you are ready to integrate E*I*y'' =M(x) to get the deflection y(x).

If the shaft is uniform, this is quite possibly something you can do in closed form. If it is not uniform, it may be necessary to resort to numerical integration to solve the DE. C.R. Mischke developed a neat method for dealing with many point loads on a non-uniform shaft; you may want to look for it in the literature.
 
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  • #6
Dr.D said:
If you have the moment function, then you are ready to integrate E*I*y'' =M(x) to get the deflection y(x).

If the shaft is uniform, this is quite possibly something you can do in closed form. If it is not uniform, it may be necessary to resort to numerical integration to solve the DE. C.R. Mischke developed a neat method for dealing with many point loads on a non-uniform shaft; you may want to look for it in the literature.
I can't understand. I want a sample problem in order for me to understand all that you said. And also I need a reference or textbook with proper explanation in lateral deflection. One of my friend suggests that the book of P. H. Black and O. E. Adams, Jr. will help help me regarding with my problem about lateral deflection.
 
  • #7
You said that you have the moment diagram, M(x). Then, at that point you have a second order ODE that governs deflection,
E*I*y'' = M(x)
In principle, all that is required is to integrate twice. Assuming that E and I are constants, this comes down to
E*I*y' = int(M(x), dx) + c1
E*I*y = int(int(M(x), dx), dx) + c1*x + c2
where c1 and c2 are determined by the boundary conditions. That is really all there is to it.
 
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  • #8
Dr.D said:
You said that you have the moment diagram, M(x). Then, at that point you have a second order ODE that governs deflection,
E*I*y'' = M(x)
In principle, all that is required is to integrate twice. Assuming that E and I are constants, this comes down to
E*I*y' = int(M(x), dx) + c1
E*I*y = int(int(M(x), dx), dx) + c1*x + c2
where c1 and c2 are determined by the boundary conditions. That is really all there is to it.
Do you have a sample problem, Sir? Because I really don't understand just by the given formula.
 
  • #9
I've showed you how to work the problem in a fairly general way. Now, I think it is time for you to put forth some effort and work the specific case of interest on your own. I know how to work this problem, but I cannot learn it for you.
 
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  • #10
Dr.D said:
I've showed you how to work the problem in a fairly general way. Now, I think it is time for you to put forth some effort and work the specific case of interest on your own. I know how to work this problem, but I cannot learn it for you.
Okay Sir, thanks for all of your concern and help. I will give my best just to try to understand my own problem.
 

1. What is lateral deflection of a shaft?

Lateral deflection of a shaft refers to the amount of displacement or bending that occurs in a shaft when it is subjected to a load or force perpendicular to its axis.

2. What causes lateral deflection of a shaft?

Lateral deflection of a shaft can be caused by various factors, including the type and magnitude of the load, the material properties of the shaft, and the support conditions at its ends.

3. How is lateral deflection of a shaft measured?

Lateral deflection of a shaft is typically measured by using a dial gauge or other precision measuring device to determine the amount of displacement at specific points along the shaft.

4. What are the potential consequences of excessive lateral deflection in a shaft?

Excessive lateral deflection in a shaft can lead to reduced performance, premature wear and fatigue, and even failure of the shaft or the machine it is a part of.

5. How can lateral deflection of a shaft be prevented or minimized?

Lateral deflection of a shaft can be prevented or minimized by using appropriate design and material selection, ensuring proper alignment and support, and regularly inspecting and maintaining the shaft and its surroundings.

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