A Model to Estimate the Stress-Strain Behavior of Polyimide Electrospun Fabric

Nonwoven structures consist of fibers with different orientations. Studying the mechanical behavior of nonwoven materials is very complicated and laborious in terms of the random nature of their constituent fibers. In this study, a suitable approach based on existing models is proposed to predict the stress-strain behavior of electrospun polyimide (PI) non-woven fabric as a function of the volume fraction, orientation distribution, and stress-strain behavior of its constituent fibers. 18 different discrete orientations from 0 to 180 degrees are considered to specify the fiber orientation distribution in the fabric. To avoid difficult and complex experiments on the fibers constituting the nonwoven fabric, the constants and characteristics of the stress- strain curve of a single fiber were determined by fitting the fabric stress- strain curve predicted by the model to the results of the fabric experimental tensile test. The comparison among the predicted stress- strain curves by the model and the experimental results for PI nonwoven fabric in two different loading directions of 0 and 45 degrees shows the validity of the method used in obtaining the stress- strain behavior of the fabric.