Obtaining results in Ansys Mechanical from a Rigid Dynamics System

Hello!

I am interested in obtaining results from a rigid dynamics simulation use iron python scripting within Ansys Mechanical.

I tried using the legacy results reader to look up information on the results, but I am not sure where the documentation is for results like CFFTOT etc.

Furthermore it looks like the RBD solver is not using the same type of information as APDL, so the element id and real constant are not available under each result object in the solver data

Does anyone have any advice for a best practice on how to access the RBD results data from a Rigid Dynamics simulation? My guess is that there is a separate api that allows access to the results since it is a different solver, but I am not sure where that documentation is. I am looking for items such as the reference forces/moment and the follower forces/moments.

The motion loads transfer extension likely uses this API since it can extract things like the acceleration on a rigid body and joint loads, but there is no python code available in the installation to look at.

Any help would be appreciated, thank you for your time!

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Pernelle Marone-Hitz

Hello ! GetResultsData is a rather outdated method to extract results. I'd recommend exploring two methods:

use the Mechanical Automation API to insert the result and evaluate it, and use PlotData to access the data within this result
explore using DPF (though I am not sure how well it handles RBD results - @Ayush Kumar : thoughts ? )

Nick Ramseyer

Hi Pernelle! I've looked through the DPF documentation as well and it doesn't look like the Ansys RBD results that I'm looking for are covered. I'm guessing there is an unexposed api for the RBD solver that I can't access without having info about it. Joints in the model can have their results pulled in their reference system, so it must have a way of connecting a workbench joint to that unexposed api. It looks like it uses an .mbd file, so maybe there is a way to interact with that.

Pernelle Marone-Hitz

Hi Nick! Unfortunately I have no knowledge of RBD. Maybe @Gabriel Messager and @Ayush Kumar can provide further help.

Ayush Kumar

@Nick Ramseyer DPF doesn't expose RBD results completely, there are a selected few operators like joint forces, which work. Maybe sticking to the legacy results reader is the only option available for now. @Gabriel Messager can confirm?

Nick Ramseyer

Hey @Ayush Kumar and @Pernelle Marone-Hitz

I found some documentation in the Ansys Python interface, The RBD solver info can be accessed through the CSMOTION reference

So far it looks like it's possible to extract forces and other information using this interface, so it gets me mostly there. Although I'm having to hunt and peck through the objects in the CSMOTION to see how they work.

import clr

import os

import Ansys

import sys


clr.AddReference('Ans.Utilities')

ver=Ansys.Utilities.ApplicationConfiguration.DefaultConfiguration.VersionInfo.VersionString


awp_root=os.getenv('AWP_ROOT'+ver)

sys.path.Add(awp_root+r'\\aisol\\bin\\winx64')

clr.AddReference('Ans.MotionSolver.MSolverLib.CSMotion')


from Ans.MotionSolver.MSolverLib import CSMotion




joint_object_id = 323

joint = CSMotion.CS_Joint.Find(joint_object_id)