Author: [Bruce Zhou]
Affiliation: [Jota Machinery Composites Material Prepreg Solution]
Corresponding Author: [jotamachinery@gmail.com]
Published : December 17 , 2025
Abstract
Automated Dry Fibre Placement (ADFP) has emerged as a promising alternative to traditional Automated Fibre Placement (AFP) using prepreg materials, offering advantages in material cost, storage stability, and preform permeability for subsequent resin infusion. However, the absence of resin tack and the reliance on binder activation introduce fundamental challenges in achieving reliable interlayer bonding during deposition. This paper investigates the deposition behaviour of bindered dry carbon fibre tapes processed by ADFP, focusing on the coupled effects of compaction force, process temperature, and deposition velocity. Experimental characterization, numerical modelling, and control-oriented analysis are used to link machine-level parameters to local pressure and temperature fields and, ultimately, to preform quality. The results demonstrate that dynamic ADFP consolidation produces significantly weaker interlayer bonding than static isothermal consolidation, with adhesive failure dominating under poorly controlled conditions. Optimal bonding is achieved within narrow force and temperature windows, while excessive compaction or insufficient thermal control leads to deconsolidation or interfacial failure. Joule heating is shown to be a viable and efficient heating method for ADFP when contact resistance and cooling losses are properly managed. The paper further highlights the importance of pressure distribution, roller compliance, and model-based control strategies in extending the viable process window for complex geometries. These findings provide practical guidance for the design, operation, and control of industrial ADFP systems.
Keywords
Automated Dry Fibre Placement; ADFP; Dry Fibre Tape; Binder Activation; Compaction Force; Joule Heating; Process Control
1. Introduction
Automated fibre placement technologies have become essential in the manufacture of high-performance composite structures for aerospace applications. While AFP using thermoset prepreg materials is widely established, it is associated with limitations including high material cost, restricted shelf life, and resin accumulation on processing equipment. Automated Dry Fibre Placement (ADFP) addresses several of these issues by employing bindered dry carbon fibre tapes, enabling long-term storage, cleaner processing, and highly permeable preforms suitable for resin infusion.
Despite these advantages, ADFP introduces new manufacturing challenges. In contrast to prepreg AFP, where resin tack provides immediate interply adhesion, bonding in ADFP relies on the thermal activation and flow of binder systems under highly transient, non-isothermal conditions. As a result, deposition quality is highly sensitive to process parameters, and the achievable process window is often narrow.
Industrial adoption of ADFP has been limited by insufficient understanding of how compaction force, temperature, and deposition speed interact to govern bonding quality and preform integrity. In practice, machine setpoints such as applied force or heating temperature do not directly correspond to the physical conditions at the tape–substrate interface. This mismatch leads to inconsistent bonding, adhesive failure between layers, and defects on curved or complex tools.
This paper addresses these challenges by examining the deposition behaviour of dry carbon fibre tapes in ADFP, with particular emphasis on parameter interactions, pressure distribution, thermal behaviour, and control strategies. The objective is to translate experimental and modelling insights into actionable guidance for robust ADFP process design.
2. Literature Review
Early research on automated fibre placement has focused predominantly on prepreg-based AFP, where adhesion behaviour is governed by resin viscosity, tack, and out-time effects. Numerous studies have demonstrated the dominant role of temperature and compaction in controlling prepreg adhesion and defect formation. However, these findings cannot be directly transferred to ADFP, where bonding mechanisms differ fundamentally.
In ADFP, interlayer bonding is achieved through thermoplastic or reactive binder systems applied to dry fibre tapes. Static consolidation studies have shown that sufficient time at elevated temperature can produce strong cohesive bonds. In contrast, dynamic ADFP processes provide only short thermal and mechanical interaction times, often resulting in incomplete binder flow and weak adhesive interfaces.
Previous investigations into dry fibre placement have identified compaction force and temperature as critical parameters, but reported trends are inconsistent. Some studies suggest that increasing force improves bonding, while others report degradation due to fibre bed disruption or binder squeeze-out. Similarly, heating strategies such as infrared, laser, and Joule heating have been explored, with Joule heating offering potential efficiency advantages but posing challenges related to electrical contact resistance and heat losses.
Numerical modelling approaches, including power-law compaction models and finite element simulations, have been proposed to describe dry fibre bed behaviour. However, few studies have integrated these models with experimental validation and real-time control considerations. As a result, the practical translation of modelling insights into industrial ADFP operation remains limited.
3. Methodology
The analysis presented in this paper is based on a combination of experimental characterization, analytical modelling, and numerical simulation applied to bindered dry carbon fibre tapes processed under ADFP-relevant conditions.
3.1 Materials and Tape Formats
Commercial bindered dry carbon fibre tapes were used, representing industrial ADFP feedstocks. Compared with loose fibre tows, these tapes exhibit greater through-thickness stability due to the presence of binder veils, enabling more repeatable compaction behaviour.
3.2 Dynamic Consolidation and Bonding Tests
Interlayer bonding quality was evaluated using dynamic consolidation samples produced under controlled compaction, temperature, and deposition speed conditions. Peel-based tests were employed to distinguish adhesive from cohesive failure modes, providing insight into the effectiveness of binder activation under realistic ADFP conditions.
3.3 Compaction Characterization and Modelling
Through-thickness compaction behaviour was characterized experimentally under cyclic loading. A power-law relationship between pressure and fibre volume fraction was identified and implemented in numerical models to simulate roller compaction on flat and curved tools.
3.4 Thermal Characterization and Joule Heating
Electrical and thermal properties of the dry tapes were measured to support Joule heating analysis. Contact resistance was quantified as a function of tape tension, contact angle, and temperature. Analytical and finite element models were developed to predict temperature evolution from the heating zone to the nip point.
3.5 Control Strategy Development
Control-oriented models were implemented to evaluate force and temperature regulation strategies. Model-based feed-forward control was compared with conventional PID approaches to assess performance under varying geometry and speed conditions.
4. Results
Dynamic ADFP consolidation produced significantly weaker interlayer bonding than static isothermal consolidation. Dynamic samples predominantly failed by adhesive separation at the binder interface, while static samples exhibited cohesive failure within the binder layer, indicating superior bond development.
Compaction force exhibited a clear optimum. Moderate increases in force improved bonding quality, but excessive force reduced peel resistance, likely due to fibre bed disruption and reduced effective binder distribution.
Temperature strongly influenced bonding behaviour. Dynamic bonding quality peaked at elevated temperatures relative to static consolidation, reflecting thermal losses to the roller and substrate. Below a threshold temperature, deposited layers lacked sufficient integrity for handling.
Deposition velocity affected bonding indirectly by altering thermal and mechanical dwell times. Increased speed reduced effective consolidation time, while excessively slow speeds allowed post-compaction relaxation under softened binder conditions.
Compaction modelling demonstrated that roller compliance and tool curvature strongly influence pressure distribution. Softer rollers produced broader, more uniform pressure fields and wider acceptable force windows, particularly on curved tools.
Joule heating efficiency was highly sensitive to contact resistance. Increased tape tension significantly reduced contact resistance, improving heating efficiency and interface temperature control.
5. Discussion
The results confirm that bonding is the primary bottleneck in ADFP manufacturing. Unlike prepreg AFP, where tack provides immediate adhesion, ADFP bonding must be actively developed during deposition within a narrow process window.
A key finding is that applied force is not equivalent to effective pressure. Pressure distribution, governed by roller material and tool curvature, determines whether bonding conditions are met locally. This explains why parameter sets that perform well on flat tools often fail on curved aerospace components.
Joule heating offers clear advantages for ADFP due to direct fibre heating and reduced energy losses, but only when electrical contact conditions are properly controlled. Contact resistance emerges as a dominant design and maintenance consideration rather than a secondary effect.
From a control perspective, model-based strategies outperform purely feedback-driven approaches, particularly under rapidly changing geometry or speed. As deposition rates increase, mechanical stiffness and dynamic response of the placement head become limiting factors.
6. Conclusion
This paper has examined the deposition behaviour of bindered dry carbon fibre tapes processed by Automated Dry Fibre Placement. The results demonstrate that:
- Dynamic ADFP consolidation produces weaker interlayer bonding than static consolidation, requiring precise process control.
- Both compaction force and temperature exhibit narrow optimal windows; excessive values degrade bonding quality.
- Pressure distribution, not force alone, governs consolidation effectiveness, especially on curved tools.
- Joule heating is a viable and efficient heating method when contact resistance and cooling losses are managed.
- Model-based control strategies are essential for robust ADFP operation at higher speeds and on complex geometries.
These findings provide a foundation for the industrialization of ADFP and support its application in high-rate aerospace composite manufacturing.
References
Lu, S. Deposition Behaviour of Carbon Fibres Processed by Automated Dry Fibre Placement (ADFP). PhD Thesis, University of Nottingham, 2024.
Lu, S., Evans, A., Turner, T. Analysis of roller compaction pressure distribution in automated dry fibre placement. Composite Structures, 2023.
Nguyen, C. D., Krombholz, C. Influence of process parameters and material aging on the adhesion of prepreg in AFP processes. ECCM17 Proceedings, 2016.
Brasington, A., Sacco, E., Koutsos, V. Automated fibre placement: current technologies and future opportunities. Composites Part C, 2021.