Gas Spring - Dynamic simulation

[alex_negrea]

Hi All

I tried for a while now to create a dynamic simulation to discover the forces required to open/close a lid assisted by gas springs.

We use them for various lid weights and shapes, I’ve attached one example.

I think I managed to give all the elements the correct mass/material information, use the correct joint types as well. I struggle with the Spring/Damper/jack joint. I must be doing something wrong there as it is not behaving correctly.

The info we usually get from the gas spring is total length, how much it travels and the generated force.

Any advice would be highly appreciated.

Thanks,

Alex

[TheCADWhisperer]

Attach your assembly here.

[alex_negrea]

Cheers, attached.

[TheCADWhisperer]

I don't have time right now to fix every issue, but here is the progress I made thus far -

First I added a 2D contact to limit the travel up.  I would probably change your 3D Contact to 2D Contact as the motion is in a single plane.

I suppressed the Spring Force Joints, as I first want to find the Unknown Force required to lift the lid.

Before having Inventor calculate the Unknown Force required to lift the lid (relative to Revolution 8 joint, or a Prismatic Joint once the gas spring is properly constrained (for analysis)) - I first added a nominal operator applied force to the handle to start the lift.

But there are still 5 DOM that needs to be reduced to 1.

In the process of limiting some of the DOF on the mechanism - I expect it to give me an overconstrained condition as both gas spring cylinders aren't needed (for the motion/calculations).  What I expect to do is suppress one of them, get the other one properly constrained and then after having Inventor calculate the Unknown Force, I will simply divide that by 2 (for the 2 gas springs).

Now that the required Spring Force is known - it can be applied to the mechanism.

I'll let you chew on those observations for a bit and then come back later and spend more time on this (if still needed).

[alex_negrea]

I figured it out!

Thanks heaps!

[Anonymous]

Can this be done in Fusion ? I have imported a McMaster-Carr component into my design, a simple gas strut, but I don't think it has "built-in" motion where it can compress ?