Discussion

The anticipated shear–membrane locking has been detected in two adaptation modes including modification of the initial mesh. In the case of the standard *hp*-adaptation, the admissible error value has not been achieved. This is because the estimated error level and the discretization parameters in the adapted meshes have not been determined accurately due to the locking. In the adaptation with modification based on the maximum *p* possible, the admissible error value has not been achieved. This is because only further *h*-adaptation has been performed and further *p*-adaptation has not been possible as the maximum value of *p* = 8 has already been adopted. However, the admissible error value has been confidently achieved in the adaptation with the modification of the initial mesh based on the optimized value of *p*.

#### 5.2.4. An Octant of a Membrane-Dominated Shell
