Understanding Beam Boundary Conditions for a Rotating Shaft

In summary, based on your limited information, it appears you are trying to find the static deflection curves for a beam that is located in a rotating shaft. You need to find the critical speed of the shaft, based on the loading conditions.
  • #1
Ben9622111222
31
0
Hello,

Can anyone help me find the boundary conditions of the below given beam please. Its a clamped-free beam but the overhanging sectiona and the mass makes it confusing. Actually I am puzzled about finding the initial conditions.
 

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  • #2
It's not clear what type of analysis you want to perform on this arrangement.

Based on what little information you have provided, it appears you have two overhanging beams, one of which has a mass attached to the end. If you want to do a static structural analysis, you can treat each beam independently. If there is some vibration analysis going on, the method of clamping may need to be considered.
 
  • #3
Yes. I am doing vibration analysis. Do you suggest pinned arrangement instead?
 
  • #4
Ben9622111222 said:
Yes. I am doing vibration analysis. Do you suggest pinned arrangement instead?
I'm not suggesting anything at this point. I'm just trying to understand what it is you're looking for.
 
  • #5
Kk.. Please have a look ath the link below
http://ijiet.com/wp-content/uploads/2013/02/53.pdf

You can see, that the initial conditions here are easy enough to get and also proceed forward. In my case its not, due to the overhanging section

I am trying to make an equation like equation 10 in the above link for my system.
 
  • #6
Ben9622111222 said:
Kk.. Please have a look ath the link below
http://ijiet.com/wp-content/uploads/2013/02/53.pdf

You can see, that the initial conditions here are easy enough to get and also proceed forward. In my case its not, due to the overhanging section

I am trying to make an equation like equation 10 in the above link for my system.

Is there any forced excitation of this beam? If so, where is it located?
 
  • #7
No there is no forced vibration. The rod is flexible, and it is rotated by a motor. the motor position is the clamped support shown. So when the rotation stops there will vibration at the tip. to modal this, I need to find the beam boundary conditions.
 
  • #8
Ben9622111222 said:
No there is no forced vibration. The rod is flexible, and it is rotated by a motor. the motor position is the clamped support shown. So when the rotation stops there will vibration at the tip. to modal this, I need to find the beam boundary conditions.
You need to 'model' the beam.

Well, you have certainly been keeping things close to the vest here. Based on your earlier posts, I never would have guessed you were looking at a rotating shaft.

Since the motor is located at an intermediate point in the shaft, each portion of the shaft will have two different static deflection curves, based on the loading conditions of the beam. When the beam starts to rotate, a whirling vibration will be set up. The critical speed of the shaft can be estimated by applying the Rayleigh method or Dunkerly's method.
 

1. What are beam boundary conditions?

Beam boundary conditions refer to the constraints or limitations placed on a beam structure at its ends or supports. These conditions dictate the behavior of the beam and affect its overall stability and strength.

2. What are the different types of beam boundary conditions?

There are four main types of beam boundary conditions: simply supported, cantilever, fixed, and continuous. Simply supported beams have supports at both ends that allow for rotation and movement of the beam. Cantilever beams have one end fixed and the other end free to move. Fixed beams have both ends fixed, which restricts rotation and movement. Continuous beams have more than two supports and are often used for longer spans.

3. How do beam boundary conditions affect the structural analysis of a beam?

Beam boundary conditions play a crucial role in determining the forces, stresses, and deflections in a beam. Different boundary conditions will result in different load distributions and structural responses. Therefore, it is important to accurately determine and consider the boundary conditions when analyzing a beam structure.

4. What factors should be considered when selecting beam boundary conditions?

The selection of beam boundary conditions depends on several factors, such as the type of load applied, the material properties of the beam, the span of the beam, and the desired level of stability and strength. Other factors, such as cost and construction limitations, may also influence the choice of boundary conditions.

5. Can beam boundary conditions be changed or modified after construction?

In most cases, beam boundary conditions are determined and designed before construction begins. However, in some situations, it is possible to modify or change the boundary conditions after the beam has been built. This may require additional structural support or reinforcement to ensure the stability and safety of the beam.

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