Characterization of deformations of multiaxial warp knitted fabrics during forming process

The typical structure (with four inserting yarn systems) of multi-axial warp knitted fabrics shows unsatisfactory conformability according to hemisphere pressing experiments. The structure containing only two bias inserting yarn systems (TBMWK fabric), however, proves to possess good conformability. The forming behavior of TBMWK fabric was characterized. It is found that the two bias inserting yarn systems tend to gather always along the weft direction, and the angles between them along this direction are basically linear to the perpendicular distances from the measured points to the longitudinal axis of the hemisphere. And the trendline's slope of the above relation is not sensitive to the magnitude of diameter of the pressing hemisphere. The shape of flat TBMWK fabric that can yield the corresponding hemisphere is close to a rectangular, not to a square as presented by the woven fabric.