Experimental determination of bending behavior of multilayered and multidirectionally-stitched E-Glass fabric structures for composites

Abstract

The aim of this study was to experimentally determine the bending behavior of developed multilayered multistitched E-Glass preform structures. For this reason, a bending rigidity test instrument based on the cantilever test principle was used. A bending rigidity test was conducted on all developed multilayered multistitched E-Glass preform structures. Yarn linear density and fabric density influenced the bending rigidity of single layer E-Glass fabric. The single layer fabric's bending rigidity depended on the off-axis angle orientations in the fabric plane. On the other hand, the bending rigidity of the multilayered unstitched E-Glass fabric structure depended on the number of fabric layers. The bending rigidities of the multilayered four directional hand and machine stitched E-Glass preform structures were high compared with one and two directional hand and machine stitched E-Glass preform structures. The bending rigidities of all heavy (6 step/cm) machine stitched E-Glass preform structures were high compared with light (2 step/cm) machine and hand (1 step/cm) stitched E-Glass preform structures. In addition, the bending rigidities of all developed multilayered hand and machine stitched E-Glass preform structures were higher than those of unstitched preform structures due to stitching. In addition, the multilayered multistitched preform structures showed a low order of bending curvatures compared with the multilayered unstitched preform structures. The results indicated that the number of stitching directions and stitching steps substantially affected the bending rigidity of the developed preform structures. Stitching yarn type was also a parameter for the bending behaviorof the multistitched preform structures. It was considered that the unstitched fabric structure could be easily formed whereas the directional stitched E-Glass preform structure became stiff and could not be easily formed.