A contribution to the analysis of the intrinsic shear behavior of fabrics

TLDR

The in‑plane shear behavior of textiles is the most studied mechanical property because it is essential for forming on double‑curvature surfaces, yet it is complex due to relative yarn and fiber movements, and two main tests—picture‑frame and bias—are used. This study aims to analyze and explain discrepancies between picture‑frame test results from different laboratories by linking the experimental test to the fabric’s intrinsic in‑plane shear behavior. The authors employ a simplified analytical model of the picture‑frame test and a specially instrumented picture‑frame that tracks and adjusts yarn tensions while measuring the strain field optically. They find that results from the two tests on the same fabric can differ significantly, highlighting the need to consider the test–fabric association.

Abstract

The in-plane shear behavior of textile performs is the most studied mechanical property because this mode of deformation is necessary for forming on double curvature surfaces. The resulting mechanical behavior is complex and specific considering the possibilities of relative movements between yarns and fibers. Two main tests are used: the hinged framework or ‘picture frame’ and the tensile test at 45° or ‘bias test’. Nevertheless, the results obtained by different labs using these two tests on the same fabric can be significantly different. Using a simplified analytical model of the picture frame test and a specific instrumented picture frame that enables us to track and adjust yarns tensions and to measure the strain field through optical measurements, this article analyzes and explains the origin of these discrepancies and concludes in dealing with the association between the experimental test used and the intrinsic in-plane shear behavior of a fabric.