Altair RISE

A program to recognize and reward our most engaged community members

Nominate Yourself Now!

Actuators' forces

Hi guys!

I'm working with a cinematic model (how you can see in the attachments) and I'm interested to extract the actuators' force.

Runned the analysis, MotionView showed me some warnings and I don't know if those warnings may compromise the analysis.

Moreover I'd like to know if constraints are inserted correctly.

I want to specify that when I ask the output (actuators' forces) to motion solve, I obtain some forces which aren't equivalent to those that they should really be.

Thank you in advance,

Best Regards.

<?xml version="1.0" encoding="UTF-8"?>

Find more posts tagged with

English

MotionView/MotionSolve

Accepted answers

All comments

Altair Forum User

Hi,

Those warnings are redundancies. MotionSolve automatically adjusts these redundancies but sometimes this may affect the results. So it would be better if you check the joints and remove the redundancies in your model.

I want to specify that when I ask the output (actuators' forces) to motion solve, I obtain some forces which aren't equivalent to those that they should really be.

Thank you in advance,

Can you explain please?

Altair Forum User

Hi Prakash,

how can I check the joints and remove the redundant constraints?

Anyway...actuators' forces may be around 100kN, but with this model (maybe because of redundancies) I obtained forces of about 300-400N, much lower from those expected.

Altair Forum User

You need to remove redundancies as much as you can. Joints IDs will be printed in log file with redundancies.

If possible share the entire .mdl file which gives wrong/unexpected force output. This could be due to modelling issues

Altair Forum User

i can give you the .mdl file, but to see the results you have to import the h3d file 13 times and divide every component (because I have 13 different components).

Altair Forum User

OK. let me check, thank you.

Altair Forum User

As you can see in the attachment, I've 36 excessive constraints...

All the bodies can rotate around x-axis, but they can't translate along x, y, and z axis.

I don't know how to solve this problem...

best regards

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi Prakash,

do you have any news about the problem?

Best Regards

Altair Forum User

Unfortunately no. I will share some feedback soon.

Altair Forum User

Hi @FRAIUC

I think the problem is with the motion. Instead of applying motion on the joint can you apply motion using markers?

You can change the constrain types to remove redundancies, for example.

Kiran Govind

Hi Friends,

Similar case was experienced for my analysis even though it was not too complex as it is in his case. I was trying for a throttle pedal were initially there was 12DOF extra due to presence of 2 additional unconstrained member but when I constrained also the spring force showed upto around 80N but the value of pedal force was 0.0009N maximum. Can any one help for solving this issue.

Thank you