Layup temperature is a vital factor that affects the production quality of automated fiber placement for thermoset composites.For high quality production,this paper proposes a new prediction model of layup temperature...Layup temperature is a vital factor that affects the production quality of automated fiber placement for thermoset composites.For high quality production,this paper proposes a new prediction model of layup temperature by considering the structure of infrared heater of automatic fiber placement equipment.The model was first verified by comparing with the temperature results of layup experiments.Then a prediction on the effects of heater structure arrangement on layup temperature was conducted in the model.The research shows that the length of infrared tube and the radian of reflective-film have significant influences,rather than other parameters.According to this investigation,a heater structure-based heating strategy was presented in the paper to efficiently achieve constant temperature control in variable speed layup process.展开更多
In comparison to the traditional fixed-angle trajectory,the variable-angle trajectory has a greater design space.However,it is a challenge to determine which common design curve structure is the most effective for imp...In comparison to the traditional fixed-angle trajectory,the variable-angle trajectory has a greater design space.However,it is a challenge to determine which common design curve structure is the most effective for improving mechanical performance.This work explores the effects of various design curves such as fixed-angle curve,linear curve,arc curve,sine curve,Bezier curve,and cubic polynomial curve trajectories on mechanical performance of laminates,including vibration modal performance and buckling performance.Genetic algorithm and improved NSGA-II algorithm are then used to optimize various curve structures.The results are confirmed utilizing thermoplastic Carbon Fiber(CF)/Polyether-Ether-Ketone(PEEK)laminates made by robotic fiber placement experiments.The relationship model between different mechanical performance and curve design variables is established.The optimization of variable-angle structure with mechanical properties as input variables is achieved.Meanwhile,a full-process angle-variable laying software platform from trajectory planning(CAD),trajectory optimization to manufacturing(CAM)is developed for facilitating the fiber placement application.展开更多
Prepreg stickiness is the adhesion between prepregs or between a prepreg and a mold in lay-up process.It is critical for automated fiber placement,because the stickiness should be small for smooth transport,as well as...Prepreg stickiness is the adhesion between prepregs or between a prepreg and a mold in lay-up process.It is critical for automated fiber placement,because the stickiness should be small for smooth transport,as well as large enough on the laying surface for a good placement performance.To ensure prepreg stickiness always being in the optimum laying window,placement temperature should be changed according to the laying speed.In our work,the relationship between laying speed and emissive power of heating lamp was studied.The heat transfer process between heating lamp and laying surface was analyzed and the control equation of dynamic temperature was derived.Finally,the infrared heating system was built and its effectiveness was verified based on placement experiment.展开更多
There are amounts of issues to be resolved in the process of designing the fiber placement trajectory of the cylindrical component,such as the interference between the machine and the component and the over-travel of ...There are amounts of issues to be resolved in the process of designing the fiber placement trajectory of the cylindrical component,such as the interference between the machine and the component and the over-travel of the axis of rotation on the fiber placement head.When the pressure on the cylinder surface inclines in a certain direction or at an angle within the normal plane,the motion characteristics of the rotation axis will be different.This paper analyzes the pressure angle effect of the concave cylinder surface on the motion features of a fiber placement machine.The placement area is enlarged by tilting pressure with the same lifting stroke,which is significant in preventing interference and selecting post-processing algorithm.展开更多
A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as produc...A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as product quality.The relation between path geometric property and manufacturing property was discussed and a series of experiments were carried out.Based on cubic B-Spline global fairing method,the AFP tool path was faired which decreased the tool path curvature and curvature changing rate.Compared with initial ones,the path faired by the proposed method was relatively flat and smooth,which contributed to layup efficiency and reducing bulking defects.The method was demonstrated potentials in application for AFP manufacturing,especially for aeronautic and aerospace industry practice.展开更多
Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by t...Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the modeⅡinterlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End-Notched Flexure(ENF)tests were performed to measure the interlaminar fracture toughness of unidirectional laminates under three different defect configurations,namely"Gap""Overlap"and"Gap&Overlap".A marginal decline(about-1.2%in non-precracked tests,-5.1%in precracked tests)and an obvious increase(about 15.2%in nonprecracked tests,5.2%in precracked tests)in fracture toughness were observed for the"Gap"group and the"Overlap"group,respectively.Fractographic studies which involve the metallographic observation and Scanning Electron Microscopy(SEM)observation revealed that the increases in fracture area and crack length helped improve the fracture toughness of the Overlap"group.However,the resin-rich area with high porosity induced by gaps was detrimental to the delamination resistance.To capture the interlaminar stress distribution local to imperfections,a three-dimensional numerical model was established.Gap defects facilitate the local delamination process,and the overlap defect postpones the damage onset and the propagation.展开更多
In-situ consolidation forming of high-performance thermoplastic composites by Automated Fiber Placement(AFP)is of significant interest in aerospace.During the laying process,the heating temperature has a great influen...In-situ consolidation forming of high-performance thermoplastic composites by Automated Fiber Placement(AFP)is of significant interest in aerospace.During the laying process,the heating temperature has a great influence on the quality of the formed components.A threedimensional heat transfer finite element model of Carbon Fiber(CF)/Polyether Ether Ketone(PEEK)heated by Slit Structure Nozzle Hot Gas Torch(SSNHGT)assisted AFP is proposed.The influence of gas flow rate,heat transfer distance,and laying speed on heating temperature is analysed.The results show that the overall temperature increases and then decreases as the gas flow rate increases.With the increase in heat transfer distance and laying speed,the overall temperature decreases.Meanwhile,the gas flow rate has the greatest influence on the temperature of CF/PEEK being heated,followed by the laying speed and finally the heat transfer distance.Furthermore,the model can also be extended to other fiber-reinforced polymer composites formed by hot gas torch assisted AFP,which can guide the optimization of process parameters for subsequent heating temperature control.展开更多
Automated fiber placement(AFP)enables the efficient and precise fabrication of complex-shaped aerospace composite structures with lightweight and high-performance properties.However,due to the excessive compression on...Automated fiber placement(AFP)enables the efficient and precise fabrication of complex-shaped aerospace composite structures with lightweight and high-performance properties.However,due to the excessive compression on the inner edge of the tow placed along the curved trajectory,the resulting defects represented by buckling and wrinkles in spatial tow steering can induce poor manufacturing accuracy and quality degradation of products.In this paper,a theoretical model of tow buckling based on the first-order shear deformation laminate theory,linear elastic adhesion interface and Hertz compaction contact theory is proposed to analyze the formation mechanism of the wrinkles and predict the formation of defects by solving the critical radius of the trajectory,and finite element analysis involving the cohesive zone modeling(CZM)is innovated to simulate the local buckling state of the steered tow in AFP.Additionally,numerical parametric studies and experimental results indicate that mechanical properties and geometric parameters of the prepreg,the curvature of the placement trajectory and critical process parameters have a significant impact on buckling formation,and optimization of process parameters can achieve effective suppression of placement defects.This research proposes a theoretical modeling method for tow buckling,and conducts in-depth research on defect formation and suppression methods based on finite element simulation and placement experiments.展开更多
During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is spr...During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is sprayed manually.Furthermore,it can also affect the permeability of the preform,resin injection and the quality of the vacuum assisted resin infusion(VARI)molding,resulting in a decrease in the mechanical properties of composite materials.This study utilizes dry fiber automated placement equipment and an automated spraying system to manufacture preform structures,followed by VARI process to prepare composite samples with varying setting agent contents.Subsequently,mechanical characterization including interlaminar shear,bending and tensile testing is conducted to investigate the influence of setting agent content on both the manufacturing process and the mechanical properties of composite products.The results show that the interlaminar shear strength,bending strength and tensile strength of the sample gradually decrease with the increase of the content of the setting agent.The optimal setting agent content for automated laying of dry fiber is determined to be 4%-6%,balancing the preformed body’s layup quality and its impact on mechanical properties.Compared with agent-free samples,this range results in reductions of 3% in interlaminar shear strength,9% in bending strength,11% in bending modulus,and 13%-16% in tensile strength.展开更多
Hydrogen-powered aircraft,as a cutting-edge exploration of clean-energy air transportation,impose more stringent requirements for lightweight hydrogen storage due to the limitations of aircraft weight and volume.Compo...Hydrogen-powered aircraft,as a cutting-edge exploration of clean-energy air transportation,impose more stringent requirements for lightweight hydrogen storage due to the limitations of aircraft weight and volume.Composite hydrogen storage cylinders have become one of the preferred solutions for hydrogen storage systems in hydrogen-powered aircraft due to their light weight and high strength.However,during the automated placement of high-stiffness thermoplastic composites(T700/PEEK),fibers may buckle or break in the head section.As the head radius decreases,the overlap of adjacent tows increases,resulting in an increase in the thickness of the polar pores,which is contrary to the light-weighting requirements.To solve this problem,this paper derives the trajectory algorithm as a manufacturing process limitation when thermoplastic fiber bundles are laid without wrinkles,provides a definition of the overlap rate between adjacent fibers,and the effect of different ellipsoid ratios of head profile changes on the overlap of fiber bundles is investigated.The larger the ellipsoid ratio of the prolate ellipsoid is,the smaller the overlap of gaps generated by neighboring fiber bundles is,and the overlap at the pole holes is also smaller,while the change of the oblate ellipsoid is not significant.The prolate ellipsoid has greater application and research value than the oblate ellipsoid in terms of processability,which is of great research significance for the design and fabrication of thermoplastic composite hydrogen storage cylinders for hydrogen-powered aircraft.展开更多
With the growing needs of prepreg tapes for the automated fiber placement(AFP),the deviation-rectifying of prepreg in slitting process was investigated on a self-developed 16-tow prepreg slitting and winding machine.T...With the growing needs of prepreg tapes for the automated fiber placement(AFP),the deviation-rectifying of prepreg in slitting process was investigated on a self-developed 16-tow prepreg slitting and winding machine.The process of slitting and rewinding of prepreg tape was introduced,and the reason of prepreg tape deviation in slitting process was analyzed.In order to ensure the quality of the narrow prepreg slits,the application of the fuzzy PID algorithm in a closed-loop control system was discussed.A fuzzy PID algorithm was designed by combining fuzzy rules and PID controller.By applying it to precise deviation-rectifying control strategy,the automatic control of rectification could be achieved with accuracy of 0.1 mm,which satisfies the requirement of the prepreg tape both in slitting quality and layup quality for AFP.展开更多
基金supported by the National Natural Science Foundation of China(No.51805476)the Fundamental Research Funds for the Central Universities of China(No.2019FZA4001)the Major Research plan of the National Natural Science Foundation of China(No.91748204).
文摘Layup temperature is a vital factor that affects the production quality of automated fiber placement for thermoset composites.For high quality production,this paper proposes a new prediction model of layup temperature by considering the structure of infrared heater of automatic fiber placement equipment.The model was first verified by comparing with the temperature results of layup experiments.Then a prediction on the effects of heater structure arrangement on layup temperature was conducted in the model.The research shows that the length of infrared tube and the radian of reflective-film have significant influences,rather than other parameters.According to this investigation,a heater structure-based heating strategy was presented in the paper to efficiently achieve constant temperature control in variable speed layup process.
基金co-supported by the National Natural Science Foundation of China(No.51875134)the Self-Planned Task of State Key Laboratory of Robotics and System(HIT),China(No.SKLRS202218B)the Production and Research Project of HIT Wuhu Robot Technology Research Institute,China(No.HIT-CXY-CMP1-MWLRP-21-01).
文摘In comparison to the traditional fixed-angle trajectory,the variable-angle trajectory has a greater design space.However,it is a challenge to determine which common design curve structure is the most effective for improving mechanical performance.This work explores the effects of various design curves such as fixed-angle curve,linear curve,arc curve,sine curve,Bezier curve,and cubic polynomial curve trajectories on mechanical performance of laminates,including vibration modal performance and buckling performance.Genetic algorithm and improved NSGA-II algorithm are then used to optimize various curve structures.The results are confirmed utilizing thermoplastic Carbon Fiber(CF)/Polyether-Ether-Ketone(PEEK)laminates made by robotic fiber placement experiments.The relationship model between different mechanical performance and curve design variables is established.The optimization of variable-angle structure with mechanical properties as input variables is achieved.Meanwhile,a full-process angle-variable laying software platform from trajectory planning(CAD),trajectory optimization to manufacturing(CAM)is developed for facilitating the fiber placement application.
基金supported by the Key Basic Research and Development Program(973)(No.2014CB046501)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Prepreg stickiness is the adhesion between prepregs or between a prepreg and a mold in lay-up process.It is critical for automated fiber placement,because the stickiness should be small for smooth transport,as well as large enough on the laying surface for a good placement performance.To ensure prepreg stickiness always being in the optimum laying window,placement temperature should be changed according to the laying speed.In our work,the relationship between laying speed and emissive power of heating lamp was studied.The heat transfer process between heating lamp and laying surface was analyzed and the control equation of dynamic temperature was derived.Finally,the infrared heating system was built and its effectiveness was verified based on placement experiment.
基金supported by the Equipment Development Department Project of China(No. 41422010401)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘There are amounts of issues to be resolved in the process of designing the fiber placement trajectory of the cylindrical component,such as the interference between the machine and the component and the over-travel of the axis of rotation on the fiber placement head.When the pressure on the cylinder surface inclines in a certain direction or at an angle within the normal plane,the motion characteristics of the rotation axis will be different.This paper analyzes the pressure angle effect of the concave cylinder surface on the motion features of a fiber placement machine.The placement area is enlarged by tilting pressure with the same lifting stroke,which is significant in preventing interference and selecting post-processing algorithm.
基金supported by the Major Science and Technology Projects of China (No.2016ZX04002-001-07)Basic Scientific Research Fund(56XAA15057)
文摘A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as product quality.The relation between path geometric property and manufacturing property was discussed and a series of experiments were carried out.Based on cubic B-Spline global fairing method,the AFP tool path was faired which decreased the tool path curvature and curvature changing rate.Compared with initial ones,the path faired by the proposed method was relatively flat and smooth,which contributed to layup efficiency and reducing bulking defects.The method was demonstrated potentials in application for AFP manufacturing,especially for aeronautic and aerospace industry practice.
基金the Fundamental Research Funds for the Central Universities, China (No. 2019FZA4001)
文摘Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the modeⅡinterlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End-Notched Flexure(ENF)tests were performed to measure the interlaminar fracture toughness of unidirectional laminates under three different defect configurations,namely"Gap""Overlap"and"Gap&Overlap".A marginal decline(about-1.2%in non-precracked tests,-5.1%in precracked tests)and an obvious increase(about 15.2%in nonprecracked tests,5.2%in precracked tests)in fracture toughness were observed for the"Gap"group and the"Overlap"group,respectively.Fractographic studies which involve the metallographic observation and Scanning Electron Microscopy(SEM)observation revealed that the increases in fracture area and crack length helped improve the fracture toughness of the Overlap"group.However,the resin-rich area with high porosity induced by gaps was detrimental to the delamination resistance.To capture the interlaminar stress distribution local to imperfections,a three-dimensional numerical model was established.Gap defects facilitate the local delamination process,and the overlap defect postpones the damage onset and the propagation.
基金co-supported by the National Natural Science Foundation of China(No.52205460)the Heilongjiang Provincial Natural Science Foundation of China(No.LH2023E041)the China Scholarship Council(CSC)to study abroad at the Nanyang Technological University.
文摘In-situ consolidation forming of high-performance thermoplastic composites by Automated Fiber Placement(AFP)is of significant interest in aerospace.During the laying process,the heating temperature has a great influence on the quality of the formed components.A threedimensional heat transfer finite element model of Carbon Fiber(CF)/Polyether Ether Ketone(PEEK)heated by Slit Structure Nozzle Hot Gas Torch(SSNHGT)assisted AFP is proposed.The influence of gas flow rate,heat transfer distance,and laying speed on heating temperature is analysed.The results show that the overall temperature increases and then decreases as the gas flow rate increases.With the increase in heat transfer distance and laying speed,the overall temperature decreases.Meanwhile,the gas flow rate has the greatest influence on the temperature of CF/PEEK being heated,followed by the laying speed and finally the heat transfer distance.Furthermore,the model can also be extended to other fiber-reinforced polymer composites formed by hot gas torch assisted AFP,which can guide the optimization of process parameters for subsequent heating temperature control.
基金Supported by National Natural Science Foundation of China(Grant Nos.52205003 and 51575018)Zhejiang Provincial Natural Science Foundation(Grant No.LD22E050011)Ningbo Municipal Key Projects of Science and Technology Innovation 2025 Plan(Grant No.2022Z070).
文摘Automated fiber placement(AFP)enables the efficient and precise fabrication of complex-shaped aerospace composite structures with lightweight and high-performance properties.However,due to the excessive compression on the inner edge of the tow placed along the curved trajectory,the resulting defects represented by buckling and wrinkles in spatial tow steering can induce poor manufacturing accuracy and quality degradation of products.In this paper,a theoretical model of tow buckling based on the first-order shear deformation laminate theory,linear elastic adhesion interface and Hertz compaction contact theory is proposed to analyze the formation mechanism of the wrinkles and predict the formation of defects by solving the critical radius of the trajectory,and finite element analysis involving the cohesive zone modeling(CZM)is innovated to simulate the local buckling state of the steered tow in AFP.Additionally,numerical parametric studies and experimental results indicate that mechanical properties and geometric parameters of the prepreg,the curvature of the placement trajectory and critical process parameters have a significant impact on buckling formation,and optimization of process parameters can achieve effective suppression of placement defects.This research proposes a theoretical modeling method for tow buckling,and conducts in-depth research on defect formation and suppression methods based on finite element simulation and placement experiments.
基金supported by Jiangsu Provincial Key Research and Development Program(No.BE2023014-4).
文摘During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is sprayed manually.Furthermore,it can also affect the permeability of the preform,resin injection and the quality of the vacuum assisted resin infusion(VARI)molding,resulting in a decrease in the mechanical properties of composite materials.This study utilizes dry fiber automated placement equipment and an automated spraying system to manufacture preform structures,followed by VARI process to prepare composite samples with varying setting agent contents.Subsequently,mechanical characterization including interlaminar shear,bending and tensile testing is conducted to investigate the influence of setting agent content on both the manufacturing process and the mechanical properties of composite products.The results show that the interlaminar shear strength,bending strength and tensile strength of the sample gradually decrease with the increase of the content of the setting agent.The optimal setting agent content for automated laying of dry fiber is determined to be 4%-6%,balancing the preformed body’s layup quality and its impact on mechanical properties.Compared with agent-free samples,this range results in reductions of 3% in interlaminar shear strength,9% in bending strength,11% in bending modulus,and 13%-16% in tensile strength.
基金This work was supported by Special Funds of 2023 Jiangsu Provincial Science and Technology Plan(First Batch of Innovation Capacity Building Plan)[No.ZAG23009].
文摘Hydrogen-powered aircraft,as a cutting-edge exploration of clean-energy air transportation,impose more stringent requirements for lightweight hydrogen storage due to the limitations of aircraft weight and volume.Composite hydrogen storage cylinders have become one of the preferred solutions for hydrogen storage systems in hydrogen-powered aircraft due to their light weight and high strength.However,during the automated placement of high-stiffness thermoplastic composites(T700/PEEK),fibers may buckle or break in the head section.As the head radius decreases,the overlap of adjacent tows increases,resulting in an increase in the thickness of the polar pores,which is contrary to the light-weighting requirements.To solve this problem,this paper derives the trajectory algorithm as a manufacturing process limitation when thermoplastic fiber bundles are laid without wrinkles,provides a definition of the overlap rate between adjacent fibers,and the effect of different ellipsoid ratios of head profile changes on the overlap of fiber bundles is investigated.The larger the ellipsoid ratio of the prolate ellipsoid is,the smaller the overlap of gaps generated by neighboring fiber bundles is,and the overlap at the pole holes is also smaller,while the change of the oblate ellipsoid is not significant.The prolate ellipsoid has greater application and research value than the oblate ellipsoid in terms of processability,which is of great research significance for the design and fabrication of thermoplastic composite hydrogen storage cylinders for hydrogen-powered aircraft.
基金financially supported by the National Basic Research Program of China(973Program)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities ( No. 3082615NS2015056)
文摘With the growing needs of prepreg tapes for the automated fiber placement(AFP),the deviation-rectifying of prepreg in slitting process was investigated on a self-developed 16-tow prepreg slitting and winding machine.The process of slitting and rewinding of prepreg tape was introduced,and the reason of prepreg tape deviation in slitting process was analyzed.In order to ensure the quality of the narrow prepreg slits,the application of the fuzzy PID algorithm in a closed-loop control system was discussed.A fuzzy PID algorithm was designed by combining fuzzy rules and PID controller.By applying it to precise deviation-rectifying control strategy,the automatic control of rectification could be achieved with accuracy of 0.1 mm,which satisfies the requirement of the prepreg tape both in slitting quality and layup quality for AFP.
