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Some confusion about BUSH settings in Motionview

I currently have a device that is mounted on a rubber spring. I plan to model it using a bush, but I found that during startup, the device will flatten the bush under its own gravity, which is not in bush with the actual working conditions of the device. How do I set it up and apply a preload to the bush to counteract gravity? Will this affect the performance of the bush?

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Accepted answers

Christopher_Fadanelli

Hi @Jin1 ,

I would suggest either a preload in the bushing or add a new force to offset the equipment. Are you able to share the archive model?

Best,

Christopher Fadanelli

Praful

Hello @Jin1

Yes. The total preloads in all supporting bush should match with the weight of the equipment. In addition, I would recommend to use a Static run before running transient. You may use Analysis type - "Static + Transient" in MotionView.

Christopher_Fadanelli

Hi @Jin1 ,

Yes static will be ran first to reach an equilibrium state. This can be coupled in EDEM.

Quick example, two spring mass model with static+transient.

Design Time:

When transient is ran:

Best,

Christopher Fadanelli

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All comments

Christopher_Fadanelli

Hi @Jin1 ,

You can apply a constant preload in the Preload tab. Pretend that the bushing is made up of spring/dampers along each axis. You will define the respected stiffness and damping. Do all axes need to have non-zero values? No they technically don't. I would only stress that for any directional that has stiffness applied, you need at least 1% damping in the same direction.

Are you able to provide details about the rubber spring or model?

Best,

Christopher Fadanelli

Jin1

Is it possible to offset the equipment's own gravity by preloading? Or there is a better way.

Jin1

Hello, you may have misunderstood what I mean. In multi-body computing, the equipment starts slowly, and the movement may be slower at the beginning, but the equipment will squeeze the bushing under the action of its own gravity, causing the whole equipment to sink. I just want to eliminate the deformation of the bushing under the gravity of the equipment. Then I thought of using preload, but I don't know whether this method is correct and whether it will affect the performance of the bush.

Christopher_Fadanelli

Hi @Jin1 ,

I would suggest either a preload in the bushing or add a new force to offset the equipment. Are you able to share the archive model?

Best,

Christopher Fadanelli

Praful

Hello @Jin1

Jin1

If I use static+tran for analysis, can it be understood that static is before tran, and then the system reaches a static equilibrium state? Can this setup be coupled with EDEM? I haven't had time to try yet,

Christopher_Fadanelli

Hi @Jin1 ,

Yes static will be ran first to reach an equilibrium state. This can be coupled in EDEM.

Quick example, two spring mass model with static+transient.

Design Time:

When transient is ran:

Best,

Christopher Fadanelli

image.png