Weft yarns were unravelled and removed from the weave structure prior to FTIR measurements to reduce the likelihood of spectra being recorded for the underlying warp fibres especially where weft threads had significant material loss.
Jute weft and cotton warp are common materials for Axminster carpets.
However, 3D woven composites feature more complex textile architecture then 2D woven materials, and in reality nominally straight warp and weft yarns can also possess significant waviness.
Using weft knitting as the textile formation technique minimises the need for cutting patterns, sewing, welding or gluing, when compared to conventional weaving and gives the possibility to integrate channels, openings, have varying widths and directional material properties, thus broadening the geometric design space.
Quasi-static test results revealed that the dominant damage mechanisms were matrix cracks contained within the weft yarns, which initiated at the thermally-detected material thermoelastic limit and were confirmed through SEM observations.
As mentioned earlier in the On-axis section, Lomov et al. (Ivanov et al. 2009; Lomov et al. 2009) have reported loading direction sensitivity (warp, weft, bias) of 3D woven composites but the materials were limited to ORT architecture.
Several of the most famous of these materials originated in this area, including baldachin, the richly decorated fabric with a warp of gold thread and a weft of silk, named after the city of Baghdad, and damask, named after Damascus (in Syria), the source of this richly patterned silk fabric.
But they are constructed in a similar way, using a technique called weft insertion to wrap a thin line of high-strength material such as Kevlar around a core made of specially processed elastic polyester.
The compressive strength of the materials was also found to decrease in both the warp and weft fiber directions with increasing test pressures.
Compared with prepreg taped material, the restrained damage area due to special designed stacking sequence, lamina thickness and the weft nylon binder make the woven fabric reinforcement a good choice for the fabrication of lightning protection structures.
