Dear sir,
We found that the same model which can run in Comsol 5.3a report errors in Comsol 5.4, it showed the partial defferentiation of y-axis of u(displacement) was undefined. The warned expression is shell.u_ty, which means the velocity in y-axis, it is OK in Comsol 5.3a, so what's the right expression for it in Comsol 5.4?
Best regards!!