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adaptive model-based Control for laser-assisted Fibre-reinforced tape winding

Periodic Reporting for period 2 - ambliFibre (adaptive model-based Control for laser-assisted Fibre-reinforced tape winding)

Reporting period: 2017-03-01 to 2018-08-31

Worldwide there is a steadily increasing demand for components made of fibre-reinforced plastic composites (FRP) to be used for the manufacturing of a broad range of industrial goods. Tubular structures like pipes and vessels represent a total global market value of several billion € per year. Current FRP production technologies cannot fulfil this demand, are harmful to the environment and cannot react fast enough to quick market changes.

Thus, ambliFibre aimed at fulfilling this demand by improving the diode laser-assisted tape winding (LATW) process, systems and assisting software solutions to enable an efficient and flexible production for such advanced tubular composite products out of thermoplastic unidirectional (UD) fibre-reinforced pre-impregnated raw stock material, also called prepreg or tape. The ambliFibre objectives were the following:

• Development of a machine control with integrated data-mining algorithms and easy-to-use Human-Machine-Interface (HMI);
• Building-up an integral process and machine simulation model;
• Provide the inline monitoring solution for quality assurance;
• Development of an active optics for dynamic redistribution of laser irradiation at the process area controlled using the input of a novel infrared (IR) camera and the simulation model results;
• Development and demonstration of a flexible machine concept which can produce continuously as well as discontinuously;
• Development of reliability and maintenance (R&M) models for the LATW machine and evaluation of life cycle cost (LCC);
• Evaluation of the environmental impact of the ambliFibre materials, processes and components;
• Demonstration and validation of the model-based controlled ambliFibre system technology.
After the collection of initial system and demonstrator specifications based on industrial requirements, a modular concept was pursued throughout the ambliFibre project.

Production experiments were systematically conducted and accompanied by mechanical testing of the manufactured components for generating process and quality data. This data pool formed the basis for the creation of a relational database and data-mining engine. The corresponding algorithms were continuously modified and trained to obtain the best results for offline process optimisation.

The development of dedicated simulation models was separated into a local model for online application and feedback with short computational times and a global model for offline process evaluation. The creation of the simulation models accounted for various process parameters and variables including reflectance, geometry changes and material crystallinity.

The quality monitoring approach consisted of the detection and evaluation of standardised embossments within the composite tape. For this purpose, an Ultrasonic Hot Embossing process was developed and automated. A thermographic camera was placed directly behind the nip point, where incoming tape and previously wound substrate are consolidated. A machine-learning algorithm was trained to detect the embossed features and determine the level of consolidation based on their state.

New optical components developed within ambliFibre include an adaptive laser optics and a high-speed infrared thermographic camera. The laser optics features a new concept for the combined zoom and shaping of the laser spot, so that a gradient is introduced to the intensity distribution. The camera is used to capture the temperature distribution during the process in real-time with frequencies up to 1000 Hz. The novel HMI was utilised to incorporate all data feeds, including the thermographic images by the camera, the simulation model and data-mining results and the quality feedback by the monitoring device.

All components were integrated into the ambliFibre prototype system and validated by the manufacturing of pipe and tank demonstrators. The modular approach was translated to the development of conceptual models for production systems for continuous, discontinuous and combined processing. The system design was accompanied by reliability and maintenance models determining the life cycle cost of tape winding machines down to the component level. The environmental potential of the new processing route with respect to benchmarked processing (e.g. with thermoset composite materials) was highlighted by thorough life cycle assessments.

The project results were frequently disseminated in major industrial trade fairs and exhibitions, scientific and industrial conferences, in front of customers and stakeholders as well as by a range of publications. Exploitation was carried out individually by all partners and jointly after the identification of key exploitable results.
The data mining algorithms and simulation models represent first-time tools for substantiated and ensured control of the LATW process. The temperature distribution in the welding zone between consecutive composite layers is continuously monitored by the novel infrared camera, which emits a high-frequency data stream accounting for process variations in real time. The maximum image frequencies of 1000 Hz are unparalleled in the industry. The temperature is then manipulated by the adaptive laser optics adjusting the laser intensity distribution according to the desired heat input. In comparison with existing optical solutions, the ambliFibre laser optics includes the feature of introducing a gradient into the irradiation distribution. Furthermore, the inline monitoring device presents the first-time solution to receive a direct feedback with regard to the consolidation quality directly after the welding zone.

The ambliFibre system includes all new technology and is distributed in three configurations: Continuous production of components like pipes, discontinuous production of components like pressure vessels, and a combined production cell with an easy and cost-effective change between both production scenarios. The latter presents a novelty on the market and is a cost-saving solution for small- and medium-sized enterprises looking at a versatile production solution for a variety of parts. The system design was supported by an integrated life cycle cost model determining suitable maintenance strategies down to the component level.

The technology modules were integrated, commissioned and validated within the ambliFibre prototype system, achieving Technology Readiness level (TRL) 6 by the production of pipe and tank demonstrators. The successful system validation represents a significant advancement of the LATW technology beyond the state of the art. For the first time, integrated data-mining and simulation tools help to reduce ramp-up times and experimental process validations. Quality is assured throughout the process. The laser optics and infrared thermographic camera complete the loop for integrated process control.

Altogether, the new developments boost the attractiveness of the thermoplastic tape winding process for a widespread adaption in mass production applications. This satisfies the trend towards environmentally sound and sustainable production, as the process is clean and without emissions to the environment and the produced thermoplastic composite components can be repeatably molten and therefore present a high recycling potential. This is underlined by the environmental life cycle assessment performed in ambliFibre for various production scenarios.