Warrning message - "No usable starting vectors are available; no ritz modes can be found"

[compe_ad]

Hi all! I am running into an error message while performing modal analysis using ritz vector. Please see attached image. My model works fine if I switch to eigen vector. Can you please help me understand what is the error here and how can we debug?

 

[JoshPlumSE]

How is your mass source (MASS) defined?

 

[compe_ad]

It is defined as shown below. Area load is applied to the slab under SDL load case.

 

[li0ngalahad]

probably you have some instabilities in your model (ill-conditions), unlike Eigen, Ritz most of the times will not run if there's an instability.