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How to apply spline data as SFORCE input in MSC Adams

How to apply spline data as SFORCE input in MSC Adams

How to apply spline data as SFORCE input in MSC Adams

(OP)
Dear All,
I'll be grateful if someone might help me.

I have a SPLINE which summarise the trend of a load with respect to the time. I wish to apply it as a SFORCE in MSC Adams by using a SINGLE-COMPONENT FORCE.

I'm actually using the following code "AKISPL(time,0,input_2_12, 0)" but the simulation stops running showing this message:
ERROR: At time 3.545690582E-01 the integrator is unable to start/restart. Possible Causes:
(1) The accuracy required for the numerical solution can not be attained.
Relax (increase) the value of the acceptable integration ERROR.
(2) Incompatible redundant constraints, a lock up, or a bifurcation
situation. The latter two indicate a mechanism design problem.
(3) The system includes a zero (or relatively small) mass on a part with
an unconstrained translational degree of freedom.
Make sure you have mass on all parts with translational degrees of freedom.
(4) The system includes a zero (or relatively small) inertia on a part
with an unconstrained rotational degree of freedom.
Make sure you have inertias on all parts with rotational degrees of freedom.
(5) An Adams element has a function expression that equals exactly itself.
For example,
SFORCE/id1,I=id2,J=id3,ROT,FUNC=SFORCE(id1,jflag,comp,rm),and
DIFF/id4,IMPLICIT,IC=0,FUNC=DIF1(id4).
Similarly,
VARIABLE/id5, FUNC=VARVAL(id5)*TIME
equals itself at 1 second. Avoid setting an Adams element equal to itself.
I read about someone who used "*DTOR" at the end of the code to convert units (from degrees to radians) but I don't have any rotating joint or rotating motion.

Does anyone of you know how to apply this load correctly?

Thanks in advance,

Giuseppe.

RE: How to apply spline data as SFORCE input in MSC Adams

(OP)
Hi Greg,
thanks for your reply.

I agree with you to look just at the issue 5. I also think that my problem might be related to this suggestion "VARIABLE/id5, FUNC=VARVAL(id5)*TIME" but I still don't know where the issue is in my model.

When I import the dpline data, I define the column 1 as "independent column index" (which is the time data), then I use the code mentioned before to apply the SFORCE: "AKISPL(time,0,input_2_12, 0)".

Still working on it. I'll post something if I'll fix the issue soon. In the meantime I appreciate any suggestions.

Thanks,

Giuseppe.

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