Research On Design And Printing Technology Of Continuous Carbon Fiber/Metal Wire Reinforced Multifunctional Structure

The aerospace multifunctional structures(MFS),which combines mechanical,electrical,thermal,and radiation-shielded functions to meet diverse application requirements,can greatly improve space utilization and reduce the system mass by compactly integrating a variety of functions and flexibly decreasing the number of redundant parts.Therefore,they serve as significant components of aerospace equipment.However,there are still many challenges in the design and manufacturing of MFS that restrict their further development.As MFS integrate different kinds of functions,their design,unlike that of traditional load-bearing structures,should achieve multiple aims.Not only should it be reasonable to arrange diverse functions in a limited space,but it should also establish an optimal design model coupled with multidisciplinary indexes.The highly integrated design of MFS also leads to manufacturing difficulties.Although additive manufacturing(AM)(3D printing)can be used to fabricate structures with complex shapes,the different materials in the MFS for regulating functional performances rely on their own independent fabrication devices and forming processes,which makes it difficult to constitute a unified manufacturing system.In addition,during manufacturing in an unknown and complex environment,the existing control methods lack the extraction and analysis of environmental information in real time and cannot achieve MFS printing and path planning simultaneously.In response to the above problems,the design and printing technology of aerospace MFS by using continuous carbon fiber and metal wires as reinforcements to control the structural and functional properties are investigated in this study.The panel structure is selected as the research object,and its mechanical,thermal,electrical,and radiation shielding performance requirements are analyzed.Then,the layout and optimization method of the MFS are proposed,and a multidimensional digital model that records multiple materials and process parameters is established.Based on the MFS design,AM processes of fused deposition modeling(FDM)matched with continuous carbon fiber and metal wire reinforced composites are studied,and the printing path is planned adaptively according to the characteristics of the infilled regions.Subsequently,semantic segmentation is applied to identify the unknown printing environment in real time,and an intelligent decision-making control method for the simultaneous processing of functional structure printing and path planning is developed.Finally,experimental verification of the in-situ AM of the MFS and the corresponding performance evaluation is conducted.The modular assembly of the satellite prototype is used to demonstrate the feasibility of the customization design and rapid manufacturing methods of the MFS.To design an MFS covering different requirements in a limited space and to establish the correlation between diverse functional characteristics from different disciplines,a layout method of discrete layering is proposed based on the idea of design for additive manufacturing(DFAM).The performance of each layer type is regulated by continuous carbon fiber and metal wire reinforced composites,and the mechanical,electrical,thermal,and radiation shielding features are then integrated in the design optimization model with a normalization procedure.A genetic algorithm is used to determine the design parameters with the optimization goal of functional performance maximization.According to the MFS design,a multidimensional digital model that contains different material properties and corresponding process parameters is established,and the visualization platform of the digital model is built and verified.According to the integrated manufacturing requirements of different materials in MFS design,a high-temperature composite print head compatible with flexible carbon fiber and rigid metal wire reinforcement is developed.After clarifying the relationship between the feed ratio and deposited filament width with high extrusion flux,a mechanical model describing the three-dimensional anisotropy and delamination behavior of printed structures is established based on the progressive failure principle,and the printing parameters of continuous carbon fiber and metal wire reinforced composites are investigated.Adaptive path-planning strategies based on computer graphics,deep reinforcement learning,and database search are developed for different regions in the MFS.The technological process of MFS manufacturing,from local planning to overall integration,is realized.To intelligently control the manufacturing system and enable independent decision-making in an unknown complex environment,semantic segmentation is applied to analyze the printing environment.The relationship between reality and simulation for path planning is established by extracting the environmental information.Taking the printing and repairing of the broken groove as an illustration,the Bi Se Net V2 network architecture is used to deal with low-level details and highlevel semantics separately to balance the efficiency and precision of image feature extraction.In deep reinforcement learning,a reward function including mainline and auxiliary rewards is established based on the deep Q-network(DQN)algorithm to incorporate print speed and print quality.The intelligent control method can improve the manufacturing efficiency of functional structures through the simultaneous processing of functional structure printing and path planning.Finally,the in-situ integrated AM verification of the MFS with continuous carbon fiber and metal wire reinforcement is carried out,and the mechanical,thermal,electrical,and radiation shielding functional performances of the MFS are evaluated by a combination of experiments and simulations.The traditional pure resin structure with the same overall size is selected as the control to reveal the performance improvement effects of the MFS in terms of mechanical stiffness,electrical signal transmission,heat conduction,and radiation barrier.The prototype of the micro-nano satellite is customized and tested using the proposed MFS design and manufacturing methods;the test results show that the methods can be used for the rapid assembly of aerospace equipment and ensure the normal operation of the functions,and provide a research basis for the development of aerospace equipment.