Automated Tape Placement Research Articles

Effect of plasma treatment on LMPAEK/CF tape and composites manufactured by automated tape placement (ATP)

Automated tape placement (ATP) process is widely used in aerospace for its advanced process control and multi-axis capabilities but faces issues like limited choice of materials and suboptimal tape consolidation. This study investigates air plasma treatment on ATP carbon fiber thermoplastic feedstock tape to address these challenges. The effects on low melt Polyaryletherketone/carbon fiber unidirectional tape (LMPAEK/CF UD tape) were analyzed. Treated and untreated tapes were used to fabricate composites and evaluated for physical, thermal, mechanical, and interfacial properties. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) analyses revealed surface roughness changes (on LMPAEK), extent of oxidation, and the presence of hydroxyl/carboxyl groups. Composites from plasma-treated tapes showed a 7.6% increase in tensile strength, 8% in tensile modulus, 18% in flexural strength, and 8.3% in flexural modulus. The interlaminar shear strength improved by 18.7%. Failure analysis showed untreated composites failed via inter-ply and fiber-matrix delamination, while treated composites experienced matrix cracking and fiber breakage. This study highlights atmospheric plasma treatment as a solution to ATP’s limitations, significantly enhancing LMPAEK/CF UD tape composites’ properties.

Characterisation of the Mechanical Properties of Natural Fibre Polypropylene Composites Manufactured with Automated Tape Placement

The integration of natural fibre thermoplastic composites, particularly those combining flax fibres with polypropylene, offers a promising alternative to traditional synthetic composites, emphasising sustainability in composite materials. This study investigates the mechanical properties of flax/polypropylene composites manufactured using flashlamp automated tape placement and press consolidation, individually and in combination. Tensile, compression, three-point bending, and double cantilever beam tests are utilised for comparing these manufacturing processes and the mechanical performance of the resulting composites. The microstructure of the tapes is investigated using cross-sectional microscopy, and the thermophysical behaviour is analysed utilising thermogravimetric analysis and differential scanning calorimetry. The temperature during placement is monitored using an infrared camera, and the pressure is mapped with pressure-sensitive films. The natural fibre tapes show a good aptitude for being manufactured with automated tape placement. The tensile performance of tapes manufactured with automated tape placement is close to that of press consolidated samples. Compression, flexural properties, and the mode I fracture toughness critical energy release rate all benefit from a second consolidation step.

From virtual to actual assisted tape placement − application of the Frenet frame to robotic steering trajectories

A novel computational tool is presented that integrates the design and manufacturing of variable-angle tow composites for automated tape placement, facilitating the creation of tow-steered trajectories for cut-outs. Steering movements of the robot are planned and executed within a MATLAB virtual environment via short paths and linear commands. Leveraging piecewise-continuous clothoid splines and the Frenet frame, the tool furnishes crucial details on trajectory vectors, steering angles, and curvatures. Via four integrated modules, the user can define input parameters such as the robot’s actuators and structural geometry, allowing for the subsequent visualisation of the steered trajectories as well as the generation of the manufacturing code. Finally, to assess the potential and limitations of this methodology, the file containing all details is integrated into the Kuka KR L240-2 robot model to continuously steer a carbon fibre/PEEK tape around an elliptical cut-out in a composite panel using laser-assisted tape placement, representative of an access hole in an aircraft wing.

The influence of temperature and placement rate on wound laminated carbon fibre/PEEK hoop specimens manufactured by in-situ consolidated LATP

The effect of laser-assisted automated tape placement (LATP) in-situ consolidation processing parameters on mechanical properties of manufactured laminates is an important consideration. In this study, a combination of placement rates and processing temperatures were assessed to determine their effects on wound laminated hoops for two carbon fibre (CF)/PEEK material systems, one with sized fibres and one without. It was found that these CF/PEEK material systems, while manufactured with the same LATP processing parameters, have different maximum interlaminar shear strengths, void growth characteristics and crystallinity levels. The results indicate that the placement rate has a statistically significant influence on the interlaminar shear strength and sample thickness. It was observed that there is a notable interaction between placement rate and processing temperature for the unsized fibre CF/PEEK system.

Thermal-force coupling simulation of carbon fibre-reinforced poly-ether-ether-ketone thermoplastic composites during the laser-assisted automated tape placement process

To reveal the thermal-force coupling characteristics of the laser in-situ consolidation (ISC) of carbon fibre-reinforced poly-ether-ether-ketone (CF/PEEK) composites, a two-dimensional transient thermal-force model of CF/PEEK composites was constructed using COMSOL Multiphysics finite element simulation software to calculate the temperature history and the thermal stress variation of CF/PEEK composites during the laser-assisted automated tape placement (LATP) process. The results show that the temperature field formed on the surface of each layer by the laser spot during LATP is stable, and the temperature gradient at the front of the spot movement direction is higher than that at the back edge. The maximum stresses in the laminate occur on both sides of the first CF/PEEK layer and the stresses are unevenly distributed along the length and thickness directions of the lay-up. The composite material on both sides of the laminate tends to ‘shrink’ compared to its original position.

Effect of Flashlamp Heating System Parameters on the Wedge Peel Strength of Thermoplastic Carbon Fiber Tape in the Automated Tape Placement Process

Laser-assisted automated tape placement systems are currently the state of the art regarding thermoplastic tape placement. Flashlamp heating systems are rather new in this field of application and offer high energy density with low safety requirements and moderate costs compared to laser-assisted automated tape placement systems. In this study, the effect of processing parameters on interlaminar bonding of carbon fiber-reinforced polyamide 6 tapes is investigated using a flashlamp heating system. The temperature during placement is monitored using an infrared camera, and the bonding strength is characterized by a wedge peel test. The bonding quality of the tapes placed between 210 °C and 330 °C at a lay-up speed of 50 mm/s is investigated. Thermogravimetric analysis, differential scanning calorimetry, and micrographs are used to investigate the material properties and effects of the processing conditions on the thermophysical properties and geometric properties of the tape. No significant changes in the thermophysical or geometric properties were found. Moisture within the tapes and staining of the quartz guides of the flashlamp system have significant influence on the bonding strength. The highest wedge peel strength of dried tapes was found at around 330 °C.

Trajectory optimization for automated tape placement on triangular mesh surfaces considering gap requirements

Abstract Automated tape placement (ATP) is an important automated process adopted for the fabrication of large composite components. Trajectory planning is the key link of ATP, which directly affects the precision and efficiency of the layup process, and the quality of final products. Presently, most existing trajectory optimization methods for ATP focus on smooth surfaces. Nevertheless, as commercial CAD/CAM software generally uses NURBS (Non-uniform Rational B-Splines) for modelling, the difficulty of finding the solution and the low efficiency associated with the calculation process are inevitable. The discrete methods provide alternatives for designing layup trajectories, whereas their accuracy is seldom analyzed. Furthermore, a path optimization algorithm for eliminating gap problems while preventing wrinkles on discrete models is rarely reported. In this paper, the adjustment of layup trajectories for ATP is considered on triangular meshes. Firstly, the triangular mesh is reconstructed as a Nagata patch to recover the original geometry with good accuracy. Then, a numerical method for tracing desired paths on the Nagata patch set is provided, and the computation efficiency is validated. Next, two optimization methodologies are proposed to improve the layup of composite tapes while avoiding wrinkles. Finally, the presented two strategies are examined on a discrete hyperbolic surface and a discrete freeform surface, and some of the results are delivered.

Assessing the Feasibility of Fabricating Thermoplastic Laminates from Unidirectional Tapes in Open Mold Environments

The automation of the manufacturing processes of thermoplastic composite laminates has become dependent on open mold processes such as automated tape placement (ATP), which couples tape layering with in situ consolidation. The manufacturing parameters of ATP open mold processes, which comprise processing time, consolidation pressure and temperature, affect the bond strength between the plies and the quality of the laminates produced. Therefore, the effect of the manufacturing parameters should be characterized. This work experimentally evaluates the feasibility of fabricating thermoplastic laminates using an open mold process that reasonably models that of ATP. Glass fiber-reinforced polypropylene laminates are fabricated from unidirectional tapes under different consolidation periods, pressures, and temperatures. The bond quality in the produced laminates is assessed by measuring their interlaminar shear strength, which is measured using a short beam standardized shear test in conjunction with digital image correlation. Results show that consolidation can occur at temperatures slightly below the composite tapes’ complete melting temperature, and consolidation times between 7 and 13 min can result in acceptable bond strengths. The results confirmed the feasibility of the process and highlighted its limitations. Analysis of variance and machine learning showed that the effect of process parameters on interlaminar shear strength is nonlinear.

Laser In Situ Joining as a Novel Approach for Joining Large‐Scale Thermoplastic Carbon Fiber‐Reinforced Polymer Aircraft Structures

Thermoplastic matrix composites are a viable option to reduce the carbon footprint during the life of an aircraft due to their ability to be molten and resolidified again. Tape‐based layup processes, such as automated tape placement, are well‐examined but have not seen extensive use in large‐scale joining applications, since they have to be processed layer‐by‐layer. In contrast, the advanced laser in situ joining method (CONTIjoin) utilizes fully consolidated and cut‐to‐size multilayered laminates, enabling the continuous layup of tailored laminates aligned with the mechanical application requirements. Herein, sample joints are manufactured using CONTIjoin technology, describing the general process principle, and are compared with samples produced using a standard heat press process. The base material, carbon fiber‐reinforced LMPAEK (low‐melt polyaryletherketone) is characterized using infrared spectroscopy. Using a 3.5 kW carbon dioxide (CO2) laser (10.6 μm wavelength) coupled with highly dynamic beam deflection, multidirectional reinforced laminates with up to six plies are processed to produce 24‐ply plates. The influence of joining temperatures up to 400 °C on the joint quality is investigated. Cross‐cuts are examined and interlaminar shear strength tests are conducted. With CONTIjoin, maximum strengths of 48.5 MPa are observed, reaching over 90% of the heat press reference.

Microstructural and micromechanical property characterisation of CF/PEKK composites using nanoindentation

The present work seeks to characterise the micromechanical properties of carbon fibre/poly(etherketoneketone) (CF/PEKK) composites with different crystallinity levels and morphologies. CF/PEKK laminates were manufactured under various compression-moulding and automated tape placement (ATP) conditions. Nanoindentation experiments were performed at different locations across the thickness of the laminates to evaluate hardness and elastic modulus at the micron scale. The polymer matrix of compression-moulded laminates, which was found to be fully crystallised, performed significantly better than the matrix of the ATP laminates. The central region of the ATP laminates performed slightly better than regions close to the top and bottom surfaces, likely due to a higher crystallisation development in the central area. A transition in response from the fibre to the matrix bulk was observed across all samples via nanoindentation testing. Overall, the study of micromechanical properties can provide insight into the impact of manufacturing conditions on the composite's performance at the macro scale, ultimately contributing towards higher-quality end products. To the authors’ best knowledge, the in-depth work presented in this article is the first to use nanoindentation to characterise the effect of manufacturing processes on the micromechanical properties of CF/PEKK laminates.

Effect of nanosilica on low‐velocity impact and compression after impact properties of continuous carbon fiber‐reinforced epoxy composites manufactured by 3D printing

AbstractTo improve the low‐velocity impact (LVI) and compression after impact (CAI) properties of three‐dimensional (3D)‐printed continuous carbon fiber‐reinforced epoxy composites (CFRC), nanosilica (NS) was incorporated into these composites. NS (0.5 and 1 wt%) was dispersed in a liquid epoxy matrix by ultrasonication and mechanical stirring before mixing in a planetary mixer. The addition of NS up to 1 wt% did not render any processing barrier during the extrusion followed by the automated tape placement (ATP) method, adopted in this study. The resulting “hybrid” laminates showed void content <1% and had minimal internal defects as ensured by nondestructive technique (C‐scan) and scanning electron microscopy. The neat and NS‐loaded CFRPs were subjected to an impact energy of 6 J mm−1. The rebound energy increased by ~36% with the addition of 1 wt% NS as compared to unfilled samples, obtained from the LVI test. The CAI results suggest that with 1 wt% NS the residual compressive strength increased by ~13% in comparison with the neat CFRP laminates. After impact, the damage area was reduced significantly, that is, ~62% with the addition of 1 wt% NS in comparison with the neat CFRP laminates.

Modeling and Analyzing Layup Gaps in the Trajectory Planning for Automated Tape Placement

Composite materials are widely used in the aerospace industry thanks to their lightweight along with high stiffness and strength. Automated tape placement (ATP) is an important automated process used for the fabrication of large composite structures. In ATP, the layup paths of contiguous tapes are not parallel along their lengths due to the complex contour of the mandrel, which eventually introduces gaps or overlaps between the edges of tapes. Overlaps or excessive gaps are highly undesirable as they will weaken the resulting composite member. To date, little research reveals the generation and evolution principles of placement gaps on curved mold surfaces. A better understanding of the principles would help to adjust the layup trajectories to eliminate the deposition errors and ensure the layup quality. In this paper, the evolution law of layup gaps on mold surfaces is presented at first. Then, a placement gap model is established to predict the value of gaps in the trajectory planning stage. The gap model has been validated on a series of mold surfaces. One application of this model is to optimize the placement trajectories for ATP.

Effect of crystallinity and morphology on the mechanical properties of CF/PEKK composites manufactured under compression moulding and automated tape placement

The present work aims to establish to what extent crystallisation morphology and kinetics affect the matrix-dominated properties of CF/PEKK composites, two factors which have been minimally investigated together in existing literature. Different compression-moulding cycles and automated tape placement (ATP) were used as the processing routes. Their effects on void content, crystallinity development, morphology and mechanical performance were investigated. Results showed that all compression-moulded laminates undergoing different isothermal crystallisation conditions achieved similar levels of consolidation and crystallinity, although the spherulitic development varied considerably. The effect of different crystalline structures was not evident on the properties investigated, as all compression-moulded laminates performed similarly. However, ATP laminates displayed a higher void content and low crystallinity, resulting in a lower performance across the investigated mechanical properties. While the modification of some ATP parameters resulted in slight improvements in performance in some testing, the results indicated that a thorough understanding of the correlation between processing conditions and development of crystalline structures in PEKK is needed in order to produce good-quality CF/PEKK parts under very rapid processing conditions and ensure the repeatability of this.

Characterization and comparison of thin ply IM7/8552 composites processed by automated tape placement and hand layup

Manufacturing of large composite structures is labor-intensive and challenging. Traditional processing methods can be replaced by automated approaches such as Automated Tape Placement (ATP). The focal point of this effort is on thin-ply thermoset prepreg materials which have shown better resistance to damage tolerance under applied stress when compared to standard ply-thickness materials in recent times. However, composites processed by thin-ply materials require more placement iterations to achieve the same net volume of coverage as the standard ply-thickness materials. This can increase the probability of placement defects such as gaps and overlaps, which may degrade the mechanical performance of the composite. Modifications to the existing ATP system are made to address the issues of placement defects, which resulted in improved accuracy for thin ply placement. Unidirectional and quasi-isotropic panels are fabricated from 12’’ wide unidirectional prepreg sheet with the conventional hand layup (CHL) method for the baseline property comparison with panels fabricated by the ATP process using a ¼’’ wide slit tape. This paper investigates the effects of processing defects and material variability on the mechanical properties such as tensile, Open hole tension and Bearing tests of thin ply composites. In addition, the microstructure of the fabricated thin-ply composite panels is analysed using ultrasonic C-scans and confocal microscopy to examine the processing and material quality.

One-dimensional approximation of heat transfer in flashlamp-assisted automated tape placement

A computationally efficient heat transfer simulation of flashlamp-assisted automated tape placement (ATP) is put forward in this work. The simulation combines distinct 1D finite element models representing the tow, the deposited material, and the resulting stack with appropriate transfer of temperature information to ensure field continuity. Direct comparison against a validated 2D model of ATP shows good agreement in the irradiation region, underneath and beyond the roller vicinity with errors up to 14°C. The combined solution of 1D models requires only 1-2% of the computational effort needed for an equivalent 2D analysis without compromising results resolution, whilst it is better suited for providing the full material temperature history throughout consecutive processing cycles. The accuracy and fast computation render this method appealing for studies which require an iterative execution of the model in a practical timeframe such as in optimisation schemes, inverse solutions, training of surrogate models and stochastic simulation.

In-process nip point temperature estimation in automated tape placement based on analytical solution and remote thermal measurements

The optimisation and control of automated tape placement (ATP) requires fast analysis tools able to utilise process data for predictions and monitoring. In this study, a strategy for in-process estimation of nip point temperatures is proposed. The method is based on a combination of two one-dimensional analytical solutions of heat transfer in ATP using temperature data measured on the tool surface, combined with an inverse solution for the estimation of power delivered by the heating device on the composite surface. The performance of the method is examined against a validated finite element model. Approximations of nip point temperature show good correlation for different tool materials, with an average error of 15°C and a maximum of 50°C which is satisfactory for the processing of high-temperature thermoplastic materials. The analytical scheme offers real-time estimations of the nip point temperature with the potential to be used for process control of ATP.

Isothermal crystallisation ATP process for thermoplastic composites with semi-crystalline matrices using automated tape placement machine

Continuous fibre-reinforced thermoplastic composites based on semi-crystalline thermoplastic matrices, such as PA, and PP, have been most commonly used for thermoplastic automated tape placement (ATP). However, the fluidity of the matrix and rapid cooling rate also result in some intractable defects owing to the high peak temperatures of the nip point and compaction pressures of the roller, such as warpage, matrix squeeze-out, and fibre or ply waviness. Hence, a method for controlling the substrate temperature to achieve isothermal crystallisation in the ATP process was proposed, and the effect of isothermal temperatures on the structure and performance of the laminates was studied. The results revealed that the optimised process not only reduced the defects but also ensured the bonding strength and improved mechanical properties at a low peak temperature of the nip point. • An in-situ solidification approach for thermoplastic composites integrates isothermal crystallisation and ATP process. • Modifying the performance of ATP parts using low-cost thermoplastic composites with semicrystalline matrices. • Reducing defects such as matrix squeeze-out, in-plane and out-of-plane waviness, and warpages. • Improving the bonding strength and overall bending properties.

The Factors That Affect the Expansion of the Tape for It to Avoid Side Effects in the Production of Composites in Online LATP Technology

During LATP (laser automated tape placement), the compaction roller contacts the prepreg and affects the pressure distribution directly. Moreover, the design parameters of the roller are optimized with the aim of improving pressure uniformity. This paper examines the impact of the contact line and surface that depends on the compaction force, the design of the roller, the angle of inclination and the angle of inclination of the strip. These factors significantly affect the expansion of the tape, and it is important to determine it to avoid side effects in the production of composites (formation of gaps or overlaps). Their presence increases the percentage of pores of the final material and thus reduces the mechanical properties. The results show that the pressure uniformity can be improved significantly by design optimization of the roller, which indicates that higher bond quality between layers is achieved. The lower the speed and higher the compact force in this technology give better intimate contact with a lower percentage of voids and good mechanical characteristics.

Role of resin percolation in gap filling mechanisms during the thin ply thermosetting automated tape placement process

During the automated tape placement process, gaps between adjacent tapes are created due to the limitation of machine accuracy, especially at higher speeds. These gaps are undesirable as they cause porosity, thickness variation, and fiber waviness, introducing defects in the composite part. Applying pressure and temperature to part can assist in partially or completely filling these gaps. For thermosetting resins, such processing is usually required for the material to reach complete consolidation. Modeling the tape deformation as squeeze flow of fibrous suspension in the liquid matrix is usually deployed to determine gap filling and tape deformation. However, existence of resin rich zones in the micrographs of fabricated parts suggests that there may be a second flow process involved which is the percolation of matrix through the fiber bed into the remaining empty space of the gaps. This paper extends the previous work that modeled the cross-ply deformation and squeeze flow as the primary mechanisms in the gap filling process during consolidation of thermosetting composites. Based on our experimental results, this work adds the percolation flow to the model to predict (1) the spread of fiber/matrix suspension into the gap, (2) the resin percolation out of the fiber bed into the gap and (3) the deformation of the cross (bridging) ply or plies. The governing equations are formulated, and scaling analysis is performed to estimate the effect of tape thickness on percolation flow confirming that this mechanism is more significant when thin tapes are employed. Fixed mesh numerical scheme is used to evaluate the deformation and flow progression of both the resin percolation flow and the squeeze flow of fiber/resin suspension during the consolidation process. A parametric study is conducted to evaluate the effect of model parameters. Finally, the predicted percolated resin flow along with squeeze flow advancement is compared with experimental results.

A nonparametric probabilistic method to enhance PGD solutions with data-driven approach, application to the automated tape placement process

A nonparametric method assessing the error and variability margins in solutions depicted in a separated form using experimental results is illustrated in this work. The method assess the total variability of the solution including the modeling error and the truncation error when experimental results are available. The illustrated method is based on the use of the PGD separated form solutions, enriched by transforming a part of the PGD basis vectors into probabilistic one. The constructed probabilistic vectors are restricted to the physical solution’s Stiefel manifold. The result is a real-time parametric PGD solution enhanced with the solution variability and the confidence intervals.