Answer:
Such an effect could be caused by free edges, which can be deformed almost infinitely during the form-finding process. In this case, it is difficult to achieve a state of equilibrium.
As a basis for the form-finding, there should be no free edges on the membrane surface. Cables must be arranged on the free edges of the membrane whose stiffness can be based, for example, on the folded or strengthened membrane edge strips.
