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Enabling Next Generation Composite Manufacturing by In-Situ Structural Evaluation and Process Adjustment

Final Report Summary - ECOMISE (Enabling Next Generation Composite Manufacturing by In-Situ Structural Evaluation and Process Adjustment)

Executive Summary:
Within current composite part development and manufacturing processes a disproportional high effort is implied in order to find optimal process parameters and to meet required qualities and tolerances of high performance light weight structures. The ECOMISE project enables next generation of thermoset composite manufacturing and post-processing. Within this project high precision process techniques for advanced dry fibre placement (AFP), infusion/ injection (RTI/ RTM) and curing were developed in order to maximize process efficiency at reduced costs and production time due to less material consumption, higher reproducibility, less energy, less waste and less rework.

Project Context and Objectives:
By reason of potential weight savings (up to 20%) as well as related fuel burn and emissions, e.g. automotive industry is increasingly asking for solutions of material substitution for volume parts (high throughput). Yet, manufacturing processes of high performance composites, such as carbon fibre reinforces plastics (CFRP), are either too inefficient (high process time, material and energy consumption) or they are lacking of required robustness. Therefore, a new composite manufacturing concept is required in order to ensure required robustness while significantly reducing manufacturing costs within automotive industry. Thus, to exploit lighter and high performance composite volume parts.
So-called complex parts may have complex geometric shapes (e.g. with strong curvatures or thickness variations) or complex multi-material designs in order to integrate joints for load introduction purpose or to serve specific (multi-functional) requirements. By reason of their flexibility, composites can meet these particularities for a wide range of application and thus, offer exploitation of new product properties. But yet, an immense effort and investment has to be spent on process design and hinders first-time-right manufacturing. In order to increase sustainable exploitation of complex parts, especially SMEs are requiring a new composite manufacturing processes technique, which significantly reduces ramp-up times and production costs. This is necessary to exploit European leadership for high technology applications, even across markets (e.g. automotive, aeronautic, marine, railway).
High performance large parts are mostly weight driven. But also geometric tolerances and structural weight reduction are of high importance in order to achieve current requirements. To this, unnecessary safety margins of composite design have to be exploited by identifying and minimizing manufacturing defects. Currently, extremely low manufacturing tolerances are applied, leading to very high process costs (time and energy), and yet, relatively high effort is spent on non-added value processes like rework and post-processing. Moreover, rejection rates are to be prevented in order to increase process efficiency, thus reducing overall energy and material consumption as well as CO2 and NOx emissions.
The ECOMISE project is providing a breakthrough production system to enable next generation of thermoset composite manufacturing and post-processing. Within this new approach high precision process techniques for advanced dry fibre placement (AFP), infusion/ injection (RTI/ RTM) and curing were developed in order to maximize process efficiency at reduced costs and production time due to less material consumption, higher reproducibility, less energy, less waste and less rework.
The Consortium of 11 partners from 6 countries was made up of composite manufacturers, software developers, computational mechanics experts and measurement system providers, both from industry and Academia institutions. The combination of such experience and know-how has ensured proper capitalisation of results from past and current national and international projects.

Project Results:
Facing the high complexity of composite manufacturing processes and the high sensitivity of the final composite quality with respect to inevitable process tolerances a new holistic, knowledge-based manufacturing approach is provided, which enables high performance composite application at significant reduction of production time and costs as well as related material and energy consumption. For the first time, an in-situ evaluation of the “real” determining composite properties is enabled already during manufacturing, directly coupled with an immediate, individual process adjustment. Thus, initial requirements with very low tolerances/ safety margins are ensured for future composite application without costly rework/ repair at a late production state. this breakthrough will be achieved by the new holistic ECOMISE Manufacturing System, which is not available yet. This manufacturing system combines the following four innovative technology modules: Probabilistic Process Prediction, On-line Process Monitoring, In-Situ Evaluation and In-Situ Process Adjustment.
The new module of Probabilistic Process Prediction addresses the following innovations. More reliable, physically based process simulation methods are provided in order to predict the continuous manufacturing process from first preforming of fabrics, via subsequent moulding, resin injection and curing, up to final de-moulding. Beyond, sensitive manufacturing particularities are considered for more realistic predictions. Exemplarily, preform tolerances (e.g. fabric shearing, misalignments, undulations) lead to varying material properties and thickness distribution and therefore influence the precision of subsequent infiltration. Based on the required accuracy the most efficient models are selected and implemented into the process chain for process optimization taking into account process reliability.
An innovative Online Process Monitoring is developed and integrated into production line in order to capture all prior identified sensitive process and material properties, which are determining the composite quality and defects during preforming, infusion and curing processes. Most important are: spatial fibre orientation, curvature, thickness, gaps, foreign objects, composite temperature, heat flow, resin flow front, resin gelation, glass transition or degree of cure. Respective sensor hardware (e.g. new lightening concept with reduced reflections during fibre orientation measurement or more robust tooling-integrated curing sensors for volume production) were developed. More reliable and more efficient algorithms for real-time analysis and post-processing of required properties from indirect measurements was implemented. By on-line comparison of the measured and numerically predicted data, an early assessment of possible deviations can be accomplished.
New methods and Tools for innovative In-Situ Evaluation of the affected composite quality (based on previously measured process parameters from Online Process Monitoring) are provided, that can be applied during production in case of process violations. At first, a feedback of the measured “as-built” data (from Online Process Monitoring) into the structural model takes place, e.g. of fibre orientation, thickness or degree of cure. On this, the hereby effected structural material properties (e.g. reduced stiffness from deviating fibre orientation) can be analyzed and mapped onto the respective structural simulation models. Subsequently, an automated “as-built” analysis is performed using the real composite properties, and the resulting composite quality is evaluated (e.g. load bearing capacity) with respect to the occurring manufacturing deviations.
If the required composite quality is not ensured, automatic process correction measures are provided during production by the In-Situ Process Adjustment module. This replaces current procedures of continuing subsequent process steps as initially planned and eventually allocating very high effort for later rework/ repair activities such as grinding and post-curing of porous areas or – if the case may be – even rejecting the failed product (after completing costly production).
Concluding, innovative online process monitoring systems, probabilistic process simulation methods were developed as well as a new methods and tools for in-situ structural evaluation of resulting composite properties and in-situ decision making for process adjustment. In this novel way, the required structural performance of the final composite product can be linked and assured during every manufacturing step, yet serving qualification issues at the earliest stage. Advanced characterization and testing techniques were utilized and tailored to evaluate the product quality by focussing on process robustness and throughput rate.

Potential Impact:
The resulting economic benefits of the ECOMISE approach were evaluated and demonstrated by pilot implementations for three industrial use-cases, considering particularities for high throughput volume part (car suspension), large part (aeronautic wing cover) and thick complex part (tidal blade) productions.
- Higher utilization of composites with improved performance without a cost increase for new composite applications by significantly improving composite quality through structural evaluation and selective adjustment of manufacturing tolerances
- Decrease in raw materials and energy consumption by up to 25% during manufacturing by increased process efficiency due to first-time-right process design (no manufacturing trials), in-situ process control, net-shape fibre placement, significantly reduced curing times
- Reduction of waste and emissions by up to 20% during manufacturing and post-processing (no rework or shimming during assembly) by robust net-shape manufacturing based on in-situ evaluation and immediate process adjustment

Significant impact of the project is given for SME and industry end users of composite structures (e.g. minimised process time, waste, material and energy consumption as well as higher production rate and fast ramp-up times for product changes and new composite products). Further impact is given for SME and industry system suppliers, who have implemented new technical expertise into their products in order to provide the required solutions with respect to future industrial demands (e.g. advanced sensor system hardware, reliable data acquisition and analysis tools as well as efficient simulation software for process prediction, evaluation, optimization and in-situ adjustment). Thus, newly developed methods, systems and tools are enabling a consequent and sustainable industrial utilization of enhanced composite manufacturing processes.
As a result higher competitiveness of the European Composite industry is expected, obtained by a reduced Time-to-Market of better products (high performant lighter and low cost). Since partners are involved from different industries this ensures that the benefits from ECOMISE R&T will be available for aeronautic, automotive, energy and ship building industry, with lower transfer time or industrial bottlenecks.
The positive impact on the competitiveness of the European composite industry will be turned into direct positive employment impact by securing the overall sector situation. The project will also especially secure high-education employment, with a major effort in the physical AND virtual development capabilities (sensors, automation, computational mechanics, and information technology) on top of composite related skills. This will help to develop careers with attractive high-tech content and will help to strengthen the quality of future jobs in the aeronautic, automotive and ship building industry.

List of Websites:
Project Coordinator: Dr. Tobias Wille, DLR, email: phone: +49 531 295 3012