Abstract
Recent research has shown that, during integrated piercing, the yarn tension can displace the needles from the centers of the holes in the piercing template. To reduce the damage done to the needle tips when the needles and the hole walls collide when the needle displacement is too large, this paper proposes a method for optimizing the needle shape that satisfies the strength constraint while targeting minimum needle displacement. First, the optimal objective function and strength constraint conditions for the tip displacement of the integrated puncture needle are established, which are affected by many factors. Then, the feature selection method of machine learning is used to reduce the dimensionality of the objective function after data reduction, and the feasible region of key features is reduced to avoid falling into the local best point in the optimization iteration. Finally, machine vision is used to measure experimentally the tip displacement of a needle array. The results show that the average tip displacement is reduced by 18.16–31.42% and the collision risk is reduced from 43.14% to 5.54%. It shows that the optimization method of needle shape based on feature selection is effective for reducing needle tip impact damage during integrated piercing.
Highlights
Carbon/carbon (C/C) composite preforms have received much attention in recent years because of their excellent properties of high specific strength, high specific modulus, and good ablation resistance
Integrated piercing (IP) on 3D fabrics has good overall structure and fiber volume fraction; they are excellent substrates for high-performance and heatinsulating C/C composite materials and are used widely in aircraft brake pads and rocket nozzles after curing C/C composites [1,2,3,4,5]. e distance between the needle tip of the steel needle array and the hole center of the template is determined by the structure and geometric parameters of the steel needle array [6,7,8,9,10,11]. e distance directly affects the uniformity of fiber volume fraction and the distribution of the damage degree between the tip and the hole wall
Previous studies have modeled the yarn tension around the needle bending stage during the IP of woven carbon cloth, and the curve of the needle tip has been optimized for the different IP stages, but most of those studies did not consider comprehensively how the displacement is influenced by the fabric structure, the piercing-needle shape parameters, and the piercing template parameters
Summary
Carbon/carbon (C/C) composite preforms have received much attention in recent years because of their excellent properties of high specific strength, high specific modulus, and good ablation resistance. As a special application form of truss optimization in the field of textile machinery, the shape optimization of steel needle array aiming at reducing the impact damage of needle tip is a highly nonlinear optimization problem. A feature selection method is proposed to reduce the feasible region of optimization problems under constraints. It can avoid the metaheuristic algorithm falling into the local optimal solution range of nonkey factors in the iterative solution process. A single-needle displacement model satisfying the strength requirement is proposed, which takes into account the fabric structure parameters, needle shape parameters, and punching template parameters. The results of this optimization are applied to an experiment, and data samples of the needle tip displacement of a steel needle array are obtained using machine vision. e mean and variance of the needle displacement in the needle array from the corresponding hole center of the piercing template are analyzed to test the accuracy and applicability of the theoretical model
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