Fabrication and mechanical response of commingled GF/PET composites

Abstract

The mechanical properties and the response to mechanical load of continuous glass fiber reinforced polyethylene terephthalate (GF/PET) laminates have been characterized. The laminates were manufactured by compression molding stacks of novel woven and warp knitted fabrics produced from commingled yarns. The laminate quality was examined by means of optical and scanning electron microscopy.Few voids were found and the laminate quality was good. Resin pockets occurred in the woven laminates, originating from the architecture of the woven fabric. The strength of the fiber/matrix interface was poor. Some problems were encountered while manufacturing the laminates. These led to fiber misalignment and consequently resulted in tensile mechanical properties that were slightly lower than expected. Flexural failures all initiated as a result of compression, and it is possible that the compression strength of the matrix material, rather than its tensile strength, might limit the ultimate mechanid performance of the composites. Flexural failures for both materials were very gradual. The warp knitted laminates were stronger and stiffer than the woven laminates. The impact behavior was also investigated; the woven laminates exhibited superior damage tolerance compared with the warp knitted laminates.

Fracture and fatigue performance of textile commingled yarn composites

“…The experimental values of the tensile properties were slightly lower than those predicted by the rule of mixtures [7]. These deviations were probably caused by the poor fibre/matrix adhesion and the fibre misalignment during stacking and manufacturing.…”

“…bending and shear properties, and the compression behaviour of the two fabrics were examined [7] by means of the Kawabata Evaluation System (KES), which is an established method for the characterisation of mechanical and surface properties of fabrics and non-wovens.…”

Modelling of failure of structural textile composites

“…1, were produced from air-jet texturized commingled yarns consisting of E-glass fibers (GF) and polyethylene terephtalate (PET) fibers, 50% by volume. The manufacturing and mechanical properties of commingled yarn composites have been extensively reviewed by the authors [1,2].…”

“…Both the commingled yarn fabrics were more formable than the reference wool material, mainly due to the low shear losses and the high bending stiffness of glass fiber. More information on the measure of formability and the fabric properties involved are found in [2,3].…”

“…The static mechanical properties were determined in tension, flexure and in-plane shear [2] and are detailed in Table I and figure 2. Under conditions of flexure the warp knitted laminates were stronger and stiffer than the woven laminates in the warp direction while the woven laminates were stronger and stiffer when tested in the weft direction.…”