title: Strategic Toolpath Planning for Enhancing Mechanical Performance and Quality in Additively Manufactured Continuous Fiber-Reinforced Composite Structures
Creators: name: Tawfik, Hussam Mohamed Salah
Publisher: name: Schulich School of Engineering
Year: 2024
Subjects: subject: Lightweight
subject: Additive manufacturing (AM)
subject: Continuous fiber-reinforced polymer composites (cFRPCs)
subject: Manufacturing
subject: Multi-Layer Continuous Fibre Path (ML-CFP)
subject: Strategic Cut Point Placement (SCPP)
subject: Maneuverability-based Speed and Temperature Adaptive Robotic Control (M-STARC)
subject: ABB robots
subject: Mechanical performance
subject: Toolpath planning
subject: Robotics
subject: Open-source Synchronization framework
subject: Multi-axis machinery
subject: Temperature control
subject: Speed control
subject: Thermal analysis
subject: Fibre steering
subject: Engineering--Mechanical
subject: Robotics
subject: Engineering--Industrial
subject: Plastics Technology
subject: Materials Science
subject: Chemistry--Polymer

description: The demand for lightweight, high-strength materials has intensified with the evolving needs of industries such as aerospace, automotive, and renewable energy. These sectors continually push material performance limits to develop lighter, more resilient, and energy-efficient structures. Additive manufacturing offers substantial design flexibility, enabling the production of high-performance structures tailored to specific strength requirements. However, additive manufacturing (AM) of continuous fiber-reinforced polymer composites (cFRPCs) faces core challenges in terms of manufacturability, toolpath planning, and design conception compared to the well-established conventional 3D printing using neat polymer. This thesis explores and integrates advanced toolpath planning strategies to improve the mechanical performance and manufacturing quality of additively manufactured cFRPCs. These strategies address critical challenges such as maintaining fiber continuity through structures along load paths, fiber steering, and ensuring accurate deposition on complex three-dimensional geometries with precise speed and temperature control. The first strategy implements an open-source, user-friendly synchronization framework that enables continuous fiber extrusion on both planar and non-planar surfaces using multi-axis machinery, such as commercial ABB robots. This framework provides flexible control over printing speed and extrusion rates, precisely coordinated with robotic movements. The second strategy, Multi-Layer Continuous Fibre Path (ML-CFP), enhances fiber utilization by reducing cut points and allowing fiber continuity across layers, a significant improvement over conventional layer-by-layer methods. Strategic Cut Point Placement (SCPP), supported by stress analysis, optimizes cut locations in regions with minimal tensile stress, thereby increasing the tensile strength and fracture work by up to 46\% and 100\%, respectively. Compression molding further consolidates interlayer bonding, reducing void content and enhancing interlaminar adhesion. The third strategy addresses fibre steering challenges. The Maneuverability-based Speed and Temperature Adaptive Robotic Control (M-STARC) method employs adaptive control of printing speed and the corresponding deposition nozzle temperature, adjusting them based on the complexity of robotic joint movements along steered paths. By analyzing joint maneuverability, this method reduces abrupt robot joint accelerations that may disrupt printing, thus maintaining precise deposition height and minimizing fiber damage. A system of heat transfer equations is solved for composite filaments during deposition so that the nozzle temperature can be adjusted for variable printing speeds. Collectively, these toolpath strategies advance AM for cFRPCs, providing a robust foundation for producing mechanically resilient and geometrically complex structures.