Reinforcement of knitted 3D pieces
3D knitted fabrics: knitting additive manufacturing

A knitted fabric is made up of loops, each of which contains a reserve of yarn that makes it highly deformable. However, it is possible to block the structure by inserting straight (non-corrugated), non-knitted yarns in the desired directions (figure 26 ). If these yarns have a high Young's modulus, i.e. are not very extensible, then the knitted fabric will have low or no deformability in these particular directions. An example is given in figure 27 with a circumferential reinforcement yarn in a elbow tube.