Mass matrix is not positive definite

[Anonymous]

@Rafal.Gawedaplease help. I'm getting the same error and i can't proceed with my calculations.

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

You have to create a model with accurate geometry and coherent meshes. I may not be able to move the walls so that they connect together next time. I'm attaching the corrected model.

Please watch the recordings of the 2nd Robot webinar where I explained the techniques for correcting such issues:

https://forums.autodesk.com/t5/robot-structural-analysis-forum/robot-structural-analysis-webinars/td-p/5523337

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[Anonymous]

Thanks @Artur.Kosakowski.

2

[Anonymous]

@Artur.Kosakowski, one more thing please: how come the file you have sent me is smaller as compared to what i get after running analysis?

[Artur.Kosakowski]

Hi @Anonymous

The file I attached was without results.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[Anonymous]

This problem happened to me several times because of modifications to the model. I mean, I make substantial modifications by removing old elements and adding new ones, changing the loads, a lot of changes, and this is what leads to a clash in the definitions in the model. Through experience, I chose all the elements, Then I chose save substructure and then ran the updated file, and there was no problem