Does the stress-strain behaviour of PTFE-coated glass fibre fabrics depend on the load history?

                                
==Abstract==

It is known that PTFE-coated glass fibre fabrics show a mechanical saturation behaviour under repetitive monotonous loads [1]. That means that the stress-strain behaviour changes from load cycle to load cycle. This behaviour is convergent so that stiffness values strive towards asymptote values. However, when using these fabrics in membrane structures they are subjected to various natural load histories which lead to biaxial stresses with different stress ratios in different orders. The question arises whether loads of different orders lead to a different material response. If so, stiffness parameters would not be global but would have to be given dependent on the order of loads.