Simulating a vibrating motor

[AndrewSears]

I am trying to simulate two vibrating motors on a piece of equipment.  The equipment sits on springs.  Attached is an image of one screen type.  I have a video of the motors on start up.  If it will help visualize what is going on let me know and I will email it to you.

My goal is to be able to use MES to simulate start up, run for a few seconds, shut down, and be able to accurately simulate the boundary conditions where the motors would be in contact with the support.  All of this without including the motor body.  The centrifugal force and RPM are known.  The motor body geometry and material can't be verified so I am assuming that the motor body encounters significantly less strain than the supporting structures.  The geometry of the weights generating the centrifugal force and the shaft they mount to are known.

I collected data from a physical model that we built and the results match those shown with Inventor's Dynamic Simulation (DS).  The only problem with the DS model is that I can't simulate start up, shut down, or the interactions between the weights in the vibrating motors. 

Any advice is appreciated.

Regards,

Andrew

[John_Holtz]

Hi Andrew,

I would try something like the following:

1. Use "Remote Loads" to create a "spoke" of line elements from a point on the center line of the shaft to the mounting points of the motor structure.
2. The elements could be truss if you want to minimize the stiffness effects that the motor provides, or beam elements if you want to consider the motor to be rigid.
3. At the point where the line elements come together, add one force in the vertical direction and assign it to load curve 1. And another force in the horizontal direction and assign it to load curve 2.
4. If the center of gravity (C.G.) for the motor structure is at the same point, add a lumped mass to the point to account for the motor mass. If not at the same location, draw a beam element from the C.G. to the point and apply the lumped mass at the C.G. (This would also require the line elements to be beam elements so that the mass of the motor gets properly transmitted.)
5. Use Excel to calculate the vertical force over time. The first column can be the time, the third column can be the motor speed (or acceleration and calculate the velocity from the acceleration in the fourth column, etc), and the second column would be the calculated force (F=m*w^2/r)*sine or cosine to split the force into the proper vertical component.
6. Save the spreadsheet data as a comma separated (CSV) file.
7. Import the spreadsheet data into a load curve.
8. Repeat steps 5 through 7 for the horizontal force.
9. Naturally, the load curve magnitude would be 0 after the motor stops. If the duration of the simulation is longer, you will be able to see what happens afterwards.

See the attached image, too.

[AndrewSears]

Thanks John.  I will send you an update.

Andrew

[mingyargd]

Hello Andrew, im trying to simulate exactly the same as you asked in this post, can you guide me how you did it?

Thanks