How to Control Boom Arm Deflection on a Moving Vehicle?

[richard368]

I wish to dampen a boom arm, which at its fixed point is connected to a vehicle (arm length is 5m long).
The boom is 'L shaped' is attached to the to of the vehicle and extends 5m in the horizontal, then the second leg hangs down 5m, almost to the ground. The end of the boom arms contains lead with an approximate mass of 1000kg. The boom itself is made from box section steel, dimensions are shown in the pdf.

The vehicle has a maximum acceleration, in this case, of 0.25m/s/s, I wish for the deflection at the end of the boom arm to be no more than +/-10mm.
Once a steady velocity of 0.4m/s is reached the deflection at the end of the boom arm needs to be no more than +/-5mm, within 3 seconds.

When modelling it by hand what do I need to take into account the rotation of the horizontal beam, due to torsion? What else?

I need to know I am correct with my evaluation of the displacement of the end of the boom firstly. Then I can model it on FEA to calculate what damper I need. Or can this be done by hand??

Please help


Kind regards

Henry



[PLAIN]https://www.physicsforums.com/newattachment.php?do=manageattach&p=

 

[AlephZero]

I did a quick hand calculation based on the dimensions in your drawing, and the mass of the beam itself was significantly bigger than the 1000 kg "load".

So, I would suggest the first thing to do is make a finite element model to find the vibration modes of the arm. You will probably find there are several modes that will contribute to the motion you want to control.

You could then make a 1-DOF model for each mode and find the response of the beam to the pulse of acceleration of the vehicle. That will show which modes you need to worry about, and you can then decide on the best place to put a damper and what its parameters should be.

A final check (to make sure you didn't ignore anything important) would be to do a transient dynamic analysis of the full FE model.