C-CFRTP 3D Printing Double-bridge-curves Connection Path Planning Strategy

Continuous carbon fiber reinforced thermoplastic resin matrix plastics(C-CFRTP)have been widely used for high-end equipment in aerospace,transportation and other fields due to its advantages of light weight,high strength,and easy realization of integrated component manufacturing.With the increasingly demanding performance requirements of high-end equipment,the demand for weight reduction and efficiency will become more urgent in the future.Not only will the amount of C-CFRTP continue to increase,the application range will also shift from simple structural components such as plates and barrels to impellers and honeycombs.While the traditional C-CFRTP manufacturing process represented by "laying-curing" is capable of forming simple components as a whole,it can no longer meet the precise forming requirements of complex components.In this context,C-CFRTP component 3D printing technology with high flexibility and high applicability emerged,opening up a new way for precise forming of complex components.However,myriad jumping paths and gathered connection paths could be inevitably induced due to the many types of features and scattered filling paths during FDM of complex C-CFRP parts,resulting in inferior part quality.For this point,this paper has proposed the double-bridge-curves connection path planning strategy with both continuity and scattered connection-points effect,established the implement method of both intra-layer and inter-layer scattered connection-points effects,and developed the related engineering software.The main research contents are as follows:(1)Aiming at the problem of clustering and frequent breakpoints in the 3D printing of C-CFRTP complex components,the double-bridge-curves connection scheme has been proposed with both continuity and scattered connection-points effect.The graph theory models of single-bridge-curve connection and double-bridge-curves connection have been established revealing the reasons for myriad jumping paths and gathered connection paths.Based on this,a double-bridge-curves connection path planning strategy has been established,which realized C-CFRTP raw fiber printing,simplified the structure and control system of C-CFRTP 3D printer,and broadened the application scope of co-extrusion FDM technology;(2)In order to explore the influence of different paths connection schemes and connection points distribution forms on the specimen performance,the mechanical properties of specimens using the three types strategy that single-bridge-curve connection,double-bridge-curves connection with gathered connection-points,and double-bridge-curves connection with scattered connection-points have been compared and analyzed.The results show that the use of the scattered connection-points effect could greatly improve the strength,toughness,strain rate,load synchronization and load time of the sample,which verifies the reliability of the double-bridge-curves connection path planning strategy;(3)In order to implement the double-bridge-curves connection path planning strategy,the relationship equations of the tensile strength and the connection points distance have been established between the intra-layer and inter-layer,respectively,and the law of the specimen performance enhancement made by scattered connection-points effect has been analyzed.Based on this,a synergistic enhancement method between intra-layer and inter-layer of the scattered connection-points effect has been proposed,and the effectiveness of the method has been verified through the mechanical performance test.The results show that the strength of the specimens could be increased to the state of specimens without connecting point,which provides a new idea for the realization of C-CFRTP high-performance 3D printing;(4)The C-CFRTP 3D printing path planning software and C-CFRTP 3D printing path outputting software have been developed to realize the conversion of model-paths-Gcode.Own to the two sorts of software,many complex feature specimens(such as concave holes,honeycombs,quilting frames,et al)have been successfully printed,which has improved the efficiency and accuracy of path planning.