Velocity results not saved by default on dynamic response analysis

Sergio

Hi Victor, would be possible in the next version to have the velocity results saved by default in dynamic response analysis? Now as is not saved, i'ts necessary to re-run the calculus if one missed to ask for before.

mmartin

Sergio, last week I copied the displacements over time (of a single node )into an excel file in order to determine velocities and accelerations.
And I also plotted the results.
I must admit this is stuff and you can be wrong anytime due to hand made operations and copy and paste things.
I wish this should the implemented in future versions of MW or CCX or both.

Manuel

Victor

This is a tricky design compromise.

What happens now is if there are no field variables (such as first time solving a new model), it automatically adds most of the relevant ones that can't be generated after solving, and that includes velocity for dynamic response.

But since that's usually only on the first solve, if you've already solved it as, say, static, then change to dynamic response, it doesn't automatically add more field variables and you end up not having velocity.

I'm a bit reluctant to make it add field variables when you change analysis type because you might switch back and forth between them have an unwanted velocity to keep popping back up and having to delete it over and over again. Maybe that's an acceptable price to pay to avoid having to repeat the solve though. I'm not sure.

Sergio

That was the problem, I start with a modal analysis to check that all the parts of the assembly stay glued, and then change to dynamic response analysis... one hour solving and have finish without velocity results.

Victor

Sorry about that. It's been a frustration for others too. In some cases, it shows a warning, but probably not for velocity. Hopefully I can find a solution.

prop_design

Hi Victor,

Didn't the old versions of Mecway use to automatically create the results when you selected an analysis. I thought this was something that changed a few versions back. I really liked when it automatically created the results. I was really sad to see that feature go. To solve the issue you are worried about, perhaps a pop-up warning would work. So if you select a new analysis, it would warn you that you were about to delete the current results. One other thing along the same lines would be if you created a linear or non-linear analysis then you switched to modal analysis with pre-stress, it would use those results. Right now it has to re-solve for stress, so it's wasted compute time. Also, it only uses linear pre-stress. I would be nice to have the option to use non-linear pre-stress. I'm not really sure how to elegantly implement that. However, this is something you can do in some software. So there has to be a way.

I guess one solution would be to have modal analysis with pre-stress as an analysis option. That way if you switched from a solved stress analysis it could ask if you wanted to save the results for the modal analysis.

Lastly, it's hard to clear out all the results when you switch analysis. Delete all would be very useful here. I have to manually delete all the formulas and things. I usually do a stress analysis and then switch to a modal analysis. It's quite a pain because of the lingering items in the solve tree.

Anthony

Victor

Yea, it used to, but it was causing problems when there was too much data, especially in dynamic response where the all the time steps can make it huge.

I probably won't get it to reuse existing stress. It's a good idea but too low priority.

I think CCX allows nonlinear prestress. It might just be a matter of adding the NLGEOM parameter. Not sure though.

Gotcha about deleting all the solution items. It's on my list.