static analysis option in MotionSolve dynamic analysis?

Han_Z_61 · 2025-01-17T13:01:16+00:00

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In MotionSolve, the initial static analysis is run before the dynamic analysis starts. For example, an initial static analysis is a gravity analysis to find the initial status of the suspension and other changes, too, before the dynamic analysis is performed.

My question is if there is option in MotionView/MotionSolve to turn off this static analysis option?

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GTT Adam

Hi @Han_Z_61,

The simulation type simply needs to be changed from STATIC+TRANSIENT to only TRANSIENT if it falls under the Default Analysis.

Hope this helps!

Adam Reid

GTT Adam

Expanding on my last post:

For the Default Analysis, the Analysis Type can be changed from TRANSIENT, to STATIC+TRANSIENT, to STATIC, etc.

However, it should be noted that for standard events from the Vehicle Tools Extension, such as driven events or KnC events, that this option is not shown:

That is because the STATIC simulation is required to get either the vehicle up to speed or to find the initial position of the half/full-car model. These are scripted events and thus taking the STATIC portion out of these events is not feasible.

What type of event are you trying to take the settling behaviour out of?

Hope this helps!

Adam Reid

Han_Z_61

Hi, Adam

Thanks for your quick response, much appreciated.

I understood the static analysis is needed to get the vehicle's initial position for the following dynamic event simulation. However, my vehicle model is set up upon the data (for example, hard-point coordinates of the suspension components like upper/lower control arms, coil spring, etc.) taken from a vehicle CAD model which is positioned under kerb weight.

Once the static analysis is conducted, the vehicle will be re-positioned due to the gravity, which moves the vehicle away from its design positions.

As you mentioned, all the events from the Vehicle Tools Extension there is not an option to deactivate the static analysis.

Do you have any ideas to resolve this "problem"?

Han Z

GTT Adam

Hi @Han_Z_61,

Don't you want the vehicle to adjust under gravity? If the assembled position is set to curb weight and you are simulating it at GVW, then you should want the suspension to adjust accordingly. If you are worried about springs, set the preloads to free length instead of force so that it will accommodate any vehicle mass configuration.

Hope this helps!

Adam Reid

Han_Z_61

Many thanks, Adam

To answer your question, "Don't you want the vehicle to adjust under gravity?"

In some use case, the answer is YES as you mentioned the vehicle needs to be adjusted if simulation is run at GVM. In other case, NO. I also want to study the vehicle at kerb weight. In this case the vehicle is not going to be re-positioned. By the way, our vehicle being developed is an autonomous electric vehicle.

I may try the spring preloads to tune the model, see what happens.

Cheers,

Han Z

GTT Adam

Hi @Han_Z_61,

It is strongly recommended to design all vehicle models so that they can easily change between mass configurations. By using the Free Length option, the User only needs to assert what the correct 0 force length is for the spring and thus the model will settle appropriately regardless of the mass of the vehicle body.

Hope this helps!

Adam Reid