13:30
Session 10: Defect Prediction and Mitigation in AFP
13:30
20 mins
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Real-time Feature Management in Multi-ply AFP Deposition
Ege Arabul, Vincent Maes, Robert Hughes, James Kratz
Abstract: The study presents a novel real-time control algorithm for managing the quality of multi-ply Automated Fibre Placement (AFP) deposition, with a focus on common AFP features including gaps and overlaps. While Automated Fibre Placement (AFP) is a critical manufacturing process for high-performance composite structures, 50% of the process time is consumed by inspection and rework steps [1]. Furthermore, depositions can feature a wide range of CFRP materials and underlying geometries, leading to the formation of common AFP defects, such as puckering, or features, such as gaps and overlaps. The study addresses these variabilities through the use of real-time control.
The initial steps of the study involved investigating the effects of key process parameters -compaction force, tow tension, and lay-up speed - on gaps and overlaps in a replicated AFP deposition scenario, illustrated in Figure 1. This characterisation work was conducted using a multi-modal in-process sensing system, which included Eddy Current (EC) sensors and laser line scanners. Features such as gaps, overlaps, puckering, and in-plane waviness within the material were quantified using the two complementary sensors, shown in Figure 2. Based on the characterisation experiments, a novel automated, in-process monitoring and rework algorithm for multi-ply AFP defects was developed. Furthermore, a feed-forward control strategy was implemented to "pre-sense" upcoming features within the multi-ply deposition, allowing for the proactive adjustment of process parameters in real-time. This integrated system was demonstrated to be capable of tuning process parameters for the given deposition scenario. The closed-loop control system developed is a significant step towards fully autonomous and defect-free composite manufacturing, enhancing preform quality, reducing waste, and increasing the reliability of the AFP process.
[1] F. Heinecke and C. Willberg, “Manufacturing-induced imperfections in composite parts manufactured via automated fiber placement,” Journal of Composites Science, vol. 3, pp. 1– 24, 2019.
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13:50
20 mins
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Real-Time Adaptive Trajectory Control for Automated Fibre Placement Using ROS-Based Defect Mitigation
Stig McArthur, Catherine Yokan, Jorn Mehnen
Abstract: We demonstrate real-time adaptive trajectory control for Automated Fibre Placement (AFP) systems using industrial middleware to eliminate common placement defects during deposition. By integrating the Robot Operating System (ROS) with the Interfacing Toolkit for Robotic Arms (ITRA), our system achieves 12ms real-time control of a 12-degree-of-freedom industrial robot, enabling on-the-fly corrections to the deposition trajectories executed on the robot based on laser profilometry feedback and controlled using standard computing hardware. The system utilised an automated defect detection system capable of detecting common placement-induced defects and applies in-process corrections to the pre-programmed trajectories to mitigate or remove the defects. The architecture is designed with future capabilities in mind, enabling on-the-fly trajectory generation that would dramatically reduce pre-production programming requirements. Real-time benchmarking and deposition trials on both 2D and 3D layup paths validate the approach, demonstrating how middleware-enabled flexibility bridges the gap between programmed deposition plans and manufacturing reality. This work establishes a practical framework for intelligent, self-correcting AFP systems that respond to material deposition irregularities in real-time rather than after-the-fact.
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14:10
20 mins
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A gravitational analogy for defect distribution in thin laminates
Brian Tatting
Abstract: The unavoidable presence of manufacturing defects in complex fiber-placed laminates, be it gaps/overlaps, fiber angle deviation, or excessive curvature, introduces potential failure initiation sites when the defects occur at the same spatial location. The ability to alter the location of the defects within a ply is under some control of the designer through the adjustment of Automated Fiber Placement (AFP) process parameters such as ply starting points and alternate layup strategies. Development of a metric to assess the best relative distribution of the defects in each ply, and thus the laminate as a whole, provides a useful design objective for the process planner. This paper presents a methodology based on Newton’s Law of Universal Gravitation that calculates the effect of multiple defect locations within a laminate using an inverse square law. The derivation of the law for points, lines, and areas residing in overlapping thin layers is presented, highlighting the contributions of proximity and orientation for each geometric type. Several examples using basic geometries are included to demonstrate the details of the calculation. The solution is extended to the realm of composites by categorizing the expected defects due to AFP manufacture as lines and polygons, and various enhancements are introduced to form a realistic metric for defect interaction and laminate design. Demonstration of the algorithm within a process planning program illustrates the usefulness of this technique for optimal distribution of manufacturing defects.
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14:30
20 mins
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Automated fiber placement based manufacturing of a satellite launcher interface frame
Thomas Zenker, Andreas Uhl, Nicola Riva, Celalettin Yumus, Luca Marinangeli
Abstract: Over the past years, MT Aerospace (MTA) has significantly advanced its expertise in the Automated Fibre Placement (AFP) manufacturing process, expanding the range of composite structures and tanks that can be manufactured using this technology. As the technological capabilities as well as the associated design knowledge have matured, MT Aerospace has leveraged AFP not only for next-generation launcher applications like a carbon-fiber-reinforced polymer (CFRP) Upper Stage for Ariane 6 and future launchers, but also for realizing substantial benefits for satellite structures including central tubes. The technology opens possibilities in terms of potential shapes to be realized in primary and secondary satellite structures. So, traditional co-bonded sandwich designs with little design freedom can be challenged by complex shapes tailored to the requirements.
One of the focussed parts is the Launcher Interface Frame (LIF) for ESA’s HARMONY mission, in which a CFRP frame represents the main interface towards the launcher.
The HARMONY mission, which OHB System is the Prime contractor for, foresees a dual launch of two spacecrafts (see Figure 1), relying on a bottom dispenser provided by the launcher authority which replaces the Vampire 1194 off-the-shelf-adapter [1].
As illustrated in Figure 2, the primary load path in the lower section of the spacecraft transitions from the structural panels (depicted as transparent), which define the characteristic trapezoidal geometry of the spacecraft, to the dual-launch adapter (highlighted in green) through four Hold-Down and Release Mechanisms (HDRMs). Furthermore, the propellant tank is accommodated within the same lower section and is structurally supported by four bipods, ensuring stable load transfer during launch and in-orbit operations.
To fully leverage the advantages of complex design solutions, an integrative approach is essential to ensure that manufacturing information such as local fiber orientations is consistently incorporated into the sizing and justification process. Alongside, the influence of geometrical design parameters on the manufacturability was simulated.
A full-scale manufacturing breadboard (MBB) was built and evaluated to demonstrate the manufacturing process and thereby conclude PDR phase. An integral manufacturing of the sandwich structure and both AFP-laid skins was followed by a one-shot autoclave curing process. Layup behaviour of the geometrically challenging sections was studied in detail. Where needed, improvement actions were derived and verified.
Following the successful completion of the Manufacturing Breadboard (MBB), a Structural Model (SM) is under development for static structural testing, planned to be carried out by MT Aerospace (MTA) in Q1 2026 to validate the mechanical performance of the primary load path. After completion of this phase, two Flight Models (FMs) will be manufactured and assembled together with all secondary structures, including brackets and sidewall panels.
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14:50
20 mins
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Improving AFP process design using Markov Chain Monte Carlo simulations of laid tows
Siddharth Pantoji, Seán McCarthy, Martijn van der Voort, Clifton-John Walle, Giovanni Zattoni, Manuel Cruz, Christos Kassapoglou, Daniël Peeters
Abstract: Gap and overlap defects in AFP composites are formed due to tow position and tow geometry occurring in the manufacturing process. The tow position variation can occur due to path inaccuracy of the robot and tow lateral movement at the compaction roller. The tow geometry variation can occur due to width variation in the supplied tow material and due to compaction of the tow under the roller during layup. Statistical data about these four sources of variations were fit with distributions and then used to simulate sections of an AFP laid tow. These tow sections were assembled in the tow length direction to construct representative synthetic tows which are similar to real tows in their waviness after layup. These synthetic tows were also assembled to create virtual laminae with gap and overlap defects which appeared similar to an experimental lamina.
Synthetic tow was simulated using two methods - Monte Carlo (MC) simulations and Markov Chain Monte Carlo (MCMC) simulations. The Monte Carlo simulations were implemented with random samples from the distributions describing the four sources of variations. Tow created using this method had more edge waviness compared to the observations of a real AFP laid tows. This was attributed to the random sampling which lead to drawn variation values which jumped drastically across the distributions rather than following continuous changes like the physical process they describe. This limitation was improved upon in the Markov Chain Monte Carlo simulations which used the Random Walk Metropolis method for sampling. In this case, the drawn variation value is located in the neighborhood of past draw from the distributions and therefore preserve continuity. This leads to synthetic tows whose waviness is more realistic than the synthetic tows created by random sampling. The virtual laminae can be used to identify the optimum programmed shift in adjacent tows to achieve the objective of achieving the right balance of gaps and overlaps. This could help reduce the extensive prototyping that is currently needed in establishing defect allowables. Another use of these simulation methods which are informed by manufacturing variation data is in prioritizing the process improvements required in tightening the AFP layup to the needed levels of quality.
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