Learning Forum

[Consti9_9]

Hello,

I am currently trying to illustrate the diffrence between a linear and a progressive spring.

For the linear spring the reaction froce is linear when I apple a displacement in the analysis.

But as shown in the picture for the progressive spring (variation in the outer diameter and the distance between windings) the reaction force still stays linear.

Do you maybe see a mistake here?

Screenshot 2022-05-07 163846.png

[peteroznewman]

The mistake is if you have not defined self-contact between the turns of the spring coil. If the coils pass through each other in the simulation, you will get a linear spring. It is only progressive when adjacent coils touch each other.

[Consti9_9]

Okay, how can I define this option?

[peteroznewman]

Add a frictional contact and select the coil surface as both the target and the contact side of the pair.
Try solving this in Static Structural instead of Explicit Dynamics.

[Consti9_9]

So there is no way that the progressiv spring characteristics can be seen in an structual transient analysis?

-> I was trying to simulate a Suspension with a progressiv Spring and with a linear spring and see the diffrences there

Tried simulation but with the static simulation I can not see the force over time

[peteroznewman]

In Static Structural, you would apply a displacement to compress the spring over 1 second. You can see the force over time if you insert a Probe, Reaction Force on the Displacement.
In Transient Structural, you could apply a displacement to compress the spring over 1 second.

[Consti9_9]

So there is no diffrence between the static and the transient other then the mass which is calculated in the transient with what you said or?

With the static analysis I have problems with showing me the reaction force over the probe feature but I have to try that again

[peteroznewman]

The main difference between static and transient structural analysis are the extra terms in the equation.
Statics is [K]{x} = {F}
Transient is [M]{a} + [C]{v} + [K]{x} = {F(t)}

[Consti9_9]

Yeah this i know, but if I simulate this in static I canÔÇÖt see the force over time it just shows me the final condition

[peteroznewman]

Not true. In Static Structural, under Analysis Settings, use Minimum Substeps larger than 1 and you will get results on the way to the final condition. For example, if you set the Minimum Substeps to 31, you will get 30 results between 0 and the final condition.

[Consti9_9]

I tried to do substeps and there is not a progressive Force reaction either am I doing something wrong here?

And just for future simulations as u know Ansys very well, when I simulate a suspension in transient strucutal simulation does the linear and progressive behaviour from the spring have an effect on the solutions? Because I dont see any huge diffrences in the results. But this is maybe because the spring doenst compress much or?

[peteroznewman]

Try using line elements in Static Structural as shown in this discussion: https://forum.ansys.com/discussion/20614/defining-self-contact-in-static-structural-in-spring-line-body-and-plate

[Consti9_9]

What do you mean with line elements? I have to use this exact model spring because I want to show the diffrence in this two springs?

[Consti9_9]

Maybe I can explan why I need this simulation. I simulated two suspensions one with the linear spring and the other one with the progressiv and put a displacement on the suspension. But its build like a two mass oscillator so I meassure the displacement at the top of the suspension. And there the diffrence between the progressiv and the linear is not huge which susprises me a little bit but this is maybe due to the little compression the spring does.