Adonis:  when i try starting run, the following error message appears: "zero shear modulus at element "0".
I was wondering if it was due to the assignment of mechanical properties to the materials, but I exclude it as I tried to vary the parameters.

Yes, it means the material property is not assigned to every element before solving the model.

Properties had to be reassigned. They had not been implemented initially. Now everything is regular. Thank you