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Cushion Polyurethane Sandwich Composite Structures Strengthened by a Concave-Convex Fabric Panels
Ting-Ting Li,Peiyao Liu,Bing-Chiuan Shiu,Hongyang Wang,Hao-Kai Peng,Jia-Horng Lin,Ching-Wen Lou 한국섬유공학회 2022 Fibers and polymers Vol.23 No.12
In order to improve the low velocity impact resistance, flexible PU foam composites (FPUC) with a sandwichstructure are proposed. The interlayer is composed of a concave-convex fabric structure while the top/bottom layers are madeof polyurethane foam (PU). The core is prepared as follows. Seven warp knitted spacer fabric types (WKSF) (WKSF.1-7) arelaminated with different number of layers to form cuboids, which are fixed firmly between two layers of low melting pointpolyester (LMPET) fabrics via hot melting. The effects of spacer yarn density, spacer yarn inclination angle, combination ofspacer fabrics, and number of lamination layers on the dynamic cushion performance are evaluated. With the impact energybeing 16 J, FPUs demonstrate an energy absorption level that is 19 % and 39 % greater than PU and WKSF. Furthermore,ultra-high molecular weight polyethylene fabric can effectively enhance the surface strength. Finally, the results arecomputed via theoretical prediction formulae of dynamic buffer resistance is in conformity with the experimental test results.
Zheng HaoXin,Huang MingHui,Zhan LiHua,Zhu YanMei,Liu PeiYao 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3
In the PID controller design, three sensitivity functions are used as the design indexes of mixed sensitivity. In order to select the weighted functions of the three sensitivity indexes, a method of determining the weighted functions based on dynamic tracking performance is proposed. The method is applied to the performance test of the servo control system of steering gear. The test results show that the hybrid sensitivity is used as the design index of the servo system PID control, and the control system has strong anti-interference ability and good tracking performance.