Hi Shirin Samani

You used a combination of the shell elements (S3R) and solid 3D elements (C3D4). So there are three questions:

First, are you sure that you already defined the proper sections for both of the element types?

Second, are you sure that the elements are in a good combination at their intersection in terms of the degree of freedom (to avoid the singularity)?

And third, why don’t you use only one element type to avoid the above issue?

Hi, I guess you need to determine the proper element size for your model by doing a mesh convergence. Moreover, you need to double check material properties that you are assigned for your model.

Dear Shirin,

This error is usually due to incompatible property and element type definition. Try to change your element type from surface element to shell.

Also in the property menu check what properties are assigned to the identified element set.

You can also refer to the following link:

https://www.youtube.com/watch?v=IdKyz9BTLLA

Hi Mohammadreza Moeini

Regarding the points you noticed, I checked again the detailed properties of elements in 3 matics and I found an extra surface. by deleting that surface I could do this analysis with some warning.

Thanks indeed

Shirin