Triaxial braided sandwich composite guide bar potentially used in high-speed warp knitting machine

Integrated manufacturing technology was applied to fabricate a 3-D triaxial braided sandwich composite (TBSC) guide bar based on a real geometric shape. The axial compression, three-point bending, and vibration performance of bar specimens were investigated. Frequencies and vibration modes of the TBSC bar at free and constraint conditions were obtained by the numerical model, and the parametric analysis of different braiding angles was carried out. Effectiveness of the full-scale model was verified by vibration experiments. It is found that the frequency of TBSC and steel guide bar were close at the order 1 and 2; but when the order was higher than 2, the TBSC frequency was significantly improved. For the steel bar, axial periodic torsion and cross-section distortion were found at the orders 4, 5, 6, and 8; While for the TBSC structure, transverse bending was the main vibration deformation. Under a constrained state, the bending deformation was either localized at one end or in the middle of the bar, less than 1/3 length of the whole bar. The effect of braiding angle was significant on the deformation morphology. The increase of braiding angle had a negative effect on the frequency at the order 1 to 6. But such tendency changed at higher orders from 7 to 14. The frequency of [+15/0/-15](3) and [+75/0/-75](3) TBSC bars were much lower than that of [+30/0/-30](3) and [+45/0/-45](3) counterparts. If the maximum deformed displacement is considered, the [+45/0/-45](3) configuration will be the best choice, especially for vibration resistance at high frequency.