questions about system of units in adams 1

[cromanon]

hello people, i am working with a cosimulation between adams and matlab simulink, for this i was using the mmks units system, the simulations are going great, but i have a doubt with your input units system, it turns out that the system i have simulated in adams, the input is torque, but i am not clear which is the unit of measure, they are mNm or Nm. I suppose that I can see it inside the program but I do not find where, someone can help me to clarify this doubt about the system of units referring to torques and forces.

 

[GregLocock]

The standard we use is N mm kg s. Hence g is 9801. Hopefully you'll notice the problem there.

Units are user selectable in Adams/View

Widely separated magnitudes in a matrix can cause numeric difficulties (conditioning problems).

Be careful when using inconsistent units.

Choose units so that model states (displacements and velocities) are reasonable values. For example, choosing "mm" for displacements of a rocket which travels thousands of kilometers is a poor choice.

Choose units so that stiffness values are not very large.

Choose time units appropriate to the phenomena being studied.


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[GregLocock]

At least in 2019.2 the first thing you are asked with a new model is what units to use. You can then go into /Settings/Units to see what the model uses

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[GregLocock]

Yeah, he posted in the right forum. Not like you, originally.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[cromanon]

Wow, with your example you made it very clear that we must be rigorous with the units in which you work, in fact, I had overlooked that gravity is 9801 in the MMKS system, now everything makes more sense and also I know how to change the units at will, in my case is /Settings/Units. Now I have no doubt that in my case the rotational force I have to apply should be in Nmm and not in Nm or mNm as I asked at the beginning.

Thank you very much for the answer. Regards