Resonating Dynamic Analysis

[Ramone1]

I have created a model in which the force on a point increses over the time of my analysis. I have modelled this by creating a number of forces which I apply over certain times. These forces move parts of the mechanism upwards against gravity.

When I run the dynamic analysis the results show the mechanism resonating back an forth against gravity rather than moving in a gradually upwards in a smooth motion as you would expect.

Is this how Pro-E shows this effect or am I applying the forces incorrectly. Can anyone tell me how I can change this to give a more realistic result.

Thanks in anticipation

 

[sabrejim]

I am new to ProE but have a lot of experience with FEA. I am assuming you are using Mechanica built into ProE. From your result I believe what you have run with a dynamics analysis is actual a modal analysis. This calculates the natural frequencies of the system from just the mass and stiffness of parts. Forces are ignored in this type of analysis. The plots are the mode shapes for each natural frequency.
What I think you are looking for is something called a "transient dynamic analysis". This would take into account the intertia of the objects and can include the effect of gravity. Loads can be applied as a function of time and would either be ramped between timesteps or step changed. I believe you would want ramped. I am not familiar with Mechanica so I don't know the term for this in Mechanica but I hope this helps.