Error % with AMS

Altair Forum User

Dear Experts,

 I am running 100% AMS for one of my crash simulations. The reduction in simulation time is encouraging with increase of the target time step. However I am confused with the plots of velocities,accelerations plotted with an overlay of conventional mass scaling case (/DT/NODA/CST). The plots are not matching (by default). I would like to know what would be possible error percentage for accpeting the results with respect to the velocity and acceleration plots. I know the error % with respect to mass and energy . However does the same apply for velocities and accelerations or if there is any other standard for v and a???

 

 

Thanks in advance,

Altair Forum User

Hi Raghav,

I don't think there is a standard or followed error percentage criteria for acceleration and velocity plots. I'll check regarding this and will update you if I find any details related to this.

 

gopal_rathore

Hi,

I think you can also go for a comparative study between AMS usage and natural time step case. With some hand calculations and the simulation results the effect can be seen. Generally I think AMS is not imposed during crash phenomena but can be used to accelerate time during phenomena like free fall, rigid body motion etc. I have been using it in such scenarios and has shown significant time reduction.

Altair Forum User

Hi,

 

Thanks for the reply. AMS can be used in crash phenomena as well. There are some examples of frontal crash and side impact citied on help pages. It would be really helpful for me if there is a criteria of acceptance with respect to velocities and accelerations for benchmarking the results wiith respect to that of conventional mass scaling results

Altair Forum User

Hi Raghav,

Although the Help suggests that it can be used for crash analysis it is not recommended because AMS modifies high frequencies in the system and in a dynamic event this can change results.  In quasi-static simulation this isn't an issue.