Mechanical characterization of surface wrinkling properties in fibrous sheet materials by facile folding process

Abstract

Wrinkling and folding are crucial morphological and structural motifs in polymeric sheet materials. In this study, a simultaneous-mechanical test method was proposed to evaluate the wrinkling behaviour by simply constructing the folding deformations of fibrous sheet materials. The internal relationship between fabric folding and wrinkling was studied, and the similar power law relation of the wrinkling force and the number of folded layers between wrinkling and folding of fabrics was experimentally proved. This leads to a view of wrinkling from a hierarchical folding process, laying down the way to describe the disordered wrinkling by a facile folding test. The proposed test method and instrument can simulate the complex deformation and mechanical action during the wrinkling process by curve parameters extracted from the measured force-displacement curve. The correlation analysis between the curve parameters and wrinkling grades of subjective evaluation was conducted. Moreover, the prediction model of wrinkling grades was constructed and validated to give a direct overall evaluation of wrinkling grades for industrial application. The evaluation results of the prediction model based on the proposed mechanical test method showed good agreement with the traditional subjective evaluation results, which indicated that the designed method and instrument provided a feasible and effective measurement using a facile folding process for the surface wrinkling properties of fibrous sheet materials, enhancing our design and tuning capability for the morphology instability and wrinkling of fibrous sheet materials.