CQuad4 element is distorted (Zero or negative Jacobian)

Altair Forum User

Hi all, recently when using radioss bulk data to solve, Radioss appears to have this error. However the element check i did on the model i was about 0.4. is there a way to by pass jacobian check during radioss solving or is there any remedy on this problem?

kkandra

Hi,

In control card PARAM there is a option CHECKEL. Select that option and select no under CHECKEL_V1. That way you can skip element check.

KK

Altair Forum User

instead of using PARAM,CHECKEL,NO, it would be better if you fix the quality index of your element. try by moving its nodes or split the given element or remesh your part.

Tsherig

Dear all,

I have also encountered with error as zero or negative jacobin while modelling with 1-d beam element, for solution I have tried remeshing and setting the PARAM CHECKL to NO still the error retains. The error occured for 3 different member such the the error keeps cycling once after remeshing of each member and couldnot get rid off it. Can anyone help me sort this problem? The beam section is auto/default optistruct section with channel. 

Thank you  

Peter Randle

is this due to a resolution size do you need a deck written in double precision?

As numerical round up could be the issue. 

Are the errors at the extremity of the structure, Eg where the largest Node location are?

Adriano A. Koga

Peter Randle said:

is this due to a resolution size do you need a deck written in double precision?

As numerical round up could be the issue. 

Are the errors at the extremity of the structure, Eg where the largest Node location are?

yes, this is common when modeling large structures such as airplanes, trains, etc.

exporting in long format could help in these cases.

But still it is strange for a beam element to have this issue, unless it is a 3 node beam or something like this.

I belive a couple images, and the .out file would be great.

 

Siddhee agarwal

While performing linear static analysis on bicycle frame I'm getting errors repeatedly for which  I have attached the required files please guide me on this.