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Adapted Composite Repair Tooling for in-situ wind turbine blades structural rehabilitation

Final Report Summary - CORETO (Adapted Composite Repair Tooling for in-situ wind turbine blades structural rehabilitation)

Executive Summary:
The aim of CORETO is to ‘work’ within a scheduled maintenance programme and detect and repair defects on-site without dismantling and transporting the damaged blade to an offsite workshop for repair; thereby reducing down time and cost.

Three of the most common blade damage is lighting damage, impact damage and leading edge erosion. These and other damages and defects in wind turbine blades need to be detected and evaluated in the first instance and the damaged/defective surface prepared for repair and finally repaired effectively on-site as one would have done offsite.

In CORETO the detection was carried out using an ultrasonic transducer fitted to a 500 x 500 mm inspection frame which can be manoeuvred across the entire surface of the blade. The transducer has movement capability in the X, Y, Z directions, thereby enabling a relatively large area to be scanned in quick time. The data is then analysed in real time to determine type of defect, severity and location. Once damaged area has been located, the surface is prepared by cutting out a ‘larger’ section of the blade where the damage is located. This surface preparation can be carried out using a Laser cutting tool or a mechanical cutting tool, however while both tools are acceptable in a laboratory environment, laser cutting was ruled out for on-site repair due to portability and quality of cut and the mechanical tooling was adapted and shown to give good results in a acceptable time frame. Following surface preparation the repair was concluded by laying out appropriate laminate using ‘Combined Heating and Vacuum Bag’ technology from the aerospace industry specially adapted to the wind turbine industry.
Project Context and Objectives:
Wind turbine blade condition monitoring, maintenance and repair are important cost and safety issues for wind farm operators and owners. It is also a growing issue; wind turbine blades have a design life of typically 20 years but have only a 1 or 2 year warranty period post installation. In 2011 it was reported (Composite World 2011 Wind and Ocean Energy Seminar) that about 75,000 blades were outside this warranty period and another 84,000 blades would be added to this number in 2012. Today with the expansion of the wind energy installations, these numbers are considerably greater and consequently it becomes essential to monitor, maintain and repair blades to optimise turbine uptime. It was estimated in 2011, a turbine out of production can cost $800-$1600 (USD) per day and a blade repair $30,000 (a new blade can cost $200,000) and most off site repairs anything up to $350,000 per week.

The repair of a blade generally entails; inspections from the ground (using for e.g. a 400mm lens camera) and if defects are found up tower inspection (using a suspended work platform with technician access to the blades) to verify presence and severity of damage. Blade may need to be removed and this would require a crane to be mobilised, then the blade has to be transported and repaired at a workshop and reassembled on the nacelle, leading to a long period where energy is not produced; thus loss of income. To minimise these undesirable and costly down time, it is important to have planned or scheduled maintenance; this increases energy production availability, reduces or even eliminate catastrophic failures, large repairs, crane mobilisation and increases aerodynamic efficiency. Within this maintenance schedule, repairs undertaken on site without the removal and transportation of the wind blade for repairs to an offsite workshop would considerably lower costs and downtime.

It is important to bear in mind that damaged blades, even if still operable has already an impact on cost and potential cost associated with the damage, due to :

• Reduced energy due to poor aerodynamics and pitch errors
• Blade damage could lead to potential greater costly damage to the gearbox

With these goal in mind, the CORETO project objectives were:
1. Development of an ultrasonic scanning system to scan and detect defects on the wind turbine blade
2. Development of a scanning system to be used with the wind turbine blade on the nacelle without the necessity to remove the blade (this would necessitate a suspended work platform, this is outside the project objective)
3. Development of software with a user friendly GUI (Graphical User Interface) that allows control of the scanning, data collection, defect detection and analysis
4. The development of repair technology using Lasers and/or adapted mechanical tooling from the aerospace industry to prepare the wind blade surface, i.e. cut out the damaged region prior to ‘laminating’ using heat blankets and vacuum bagging .

Ultrasonic or ultrasound scanning comes under the umbrella of non-destructive testing or evaluation (NDT/NDE) and it is a well-established technique for structural health monitoring (SHM) of wind turbines and is well suited for composites, the material which wind turbine blades are made of. Unlike some other NDT e.g. X-rays, it is a’ Single Ended’ technique, that is the transmitter and receiver can be on the same side of the ‘Object Under Test’ (OUT). The beauty of ultrasonics (sound waves) is that cracks down to a few millimetres can be detected in a plane perpendicular to the direction of the sound wave propagation and a spatial resolution (in depth) can be obtained from time delay of return signals. This is the concept used in this CORETO project for scanning and detection of damage on/in wind turbine blades.

Laser processing i.e. cutting of the damaged area, offers certain advantages over mechanical cutting in that it is contact free, no forces and thus no wear and tear of cutting discs and easily automatable. As for drawbacks, particularly in the context of on-site repair at high altitudes is; the laser is not easily portable, some safety concerns and most importantly the cut rate and cut quality compared to mechanical means of cutting exists. In relation to wind blade surface preparation prior to final repair, laser processing involves a high intensity laser beam, ‘cutting’ involves combination of sublimation and melting, possible undercut, movement of cut debris (melt) from bottom to the side of the ‘cut hole’ due to recoil pressure and debris recasts on a cooler surface (unless vaporised or extracted).

Laser processing of Fibre Reinforced Fibre (FRP) is not by any means straight forward, in addition to above, huge differences in transition temperatures exist between fibre and Matrix (Melting/Decomposition temperature of Resin 300˚C, Glass 1300˚C and Carbon 3650˚C) and high heat conductivity of fibres parallel and perpendicular to fibre axis (Heat conductivity of Resin 0.5 W/m*K, Glass 1 W/m*K and Carbon 115 W/m*K) all this requires much optimisation (there is local variation of material thickness, composition, structure , fibre orientation etc.) this is even more challenging in a changing or open environment as on-site repair would be. Even on meeting these challenges, we have other goals to be met with laser cutting; they are the minimisation of:

• Heat affected zone (HAZ)
• Protruding fibres
• Edge delamination
• Debris or removal of debris

In addressing these we have looked at the interaction time between the FRP and the laser beam, UV, MIR, IR lasers and other process parameters (wavelength, power, cutting speed etc.) that could give us a laser cutting tool that could be adapted for on-site blade repair.

An alternative cutting tool is the mechanical tooling that is used in aeronautical applications, this can be adapted to use with wind turbine blades and more importantly with blades on-site without the removal of the blade from the nacelle. The major disadvantage of mechanical cutting is the physical contact between the cutting disc and the FRP blade. The physical contact and the application of a force to cut the FRP, could result in fibres bending and being displaced resulting in unwanted change in the structural properties near the cutting edge, additionally the abrasive nature causes wear and tear of the discs (tooling) requiring frequent replacement of the tooling, and as tooling gets used, the quality of the cut decreases. Despite these shortcomings mechanical tooling is less technologically demanding and can be utilised by technicians and engineers without intensive training and experience. The challenge in this CORETO project is to adapt this technology to on-site wind blade repair using a combined heating and vacuum bag technology.
In CORETO we explore these two repair methodologies bearing in mind the basic requirement of an on-site detection, surface preparation and repair (of wind blades) system is that it is robust, reliable, relatively cheap, safe to the operators at high altitudes and is cost effective in comparison with offsite blade repair.
Project Results:
WP No. 1: A statistical analysis of most common blade failures/faults was undertaken in this WP, together with an evaluation and analysis of existing wind turbines repair methods, taking into consideration cost analysis and reparability criteria.
Of the failures documented, it must be said that not all types of failure are “catastrophic”, which means that “in-situ” repair would be possible, thus falling within the frame of the CORETO project. Seven of the major non-catastrophic failures (types of damage) were follows:
• Type 1: Damage formation and growth in the adhesive layer joining skin and main spar flanges (skin/adhesive de-bonding and/or main spar/adhesive layer de-bonding)
• Type 2: Damage formation and growth in the adhesive layer joining the up- and downwind skins along leading /trailing edges (adhesive joint failure between skins)
• Type 3: Damage formation and growth at the interface between face and core in sandwich panels in skins and main spar web (sandwich panel face/core de-bonding)
• Type 4: Internal damage formation and growth in laminates in skin and/or main spar flanges, under tensile/compression load (delamination by a tension / buckling load)
• Type 5: Splitting and fracture of separate fibres in laminates of the skin and main spar (fibre failure in tension; laminate failure in compression)
• Type 6: Buckling of the skin due to damage formation and growth in the bond between skin and main spar under compressive load (skin/adhesive de-bonding induced by buckling, a specific type 1 case)
• Type 7: Formation and growth of cracks in the gel-coat; de-bonding of the gel-coat from the skin (gel-coat cracking and gel-coat/skin de-bonding)
In deliverable D1.1 some representative photos of these types of damage are presented.
In terms of percentage occurrence of faults by type was found to be as follows:
• Type 1 - 10.7%
• Type 2 - 22.3%
• Type 3 - 14.6%
• Type 4 - 11.7%
• Type 5 - 7.8%
• Type 6 - 11.7%
• Type 7 - 21.4%
This clearly indicates adhesive joint failure between skins and gel-coat cracking and gel-coat/skin de-bonding accounts for nearly half of all faults.
This analysis allowed the specification of the equipment that needed to be developed to be formulated, this is given in deliverable D1.2 and the equipment, techniques and processes developed in WP2, 3 and 4.
WP No. 2: The main accomplishment in this WP relates to Tasks 2.2 2.3 2.4 and 2.5. A prototype (figures 1 and 2) for automated inspection consisting of an ultrasonic NDT/NDE transducer, pulse/receiver (hardware) and an automated X, Y, Z movement hardware mounted on ‘large’ frame that could be positioned on the wind turbine blade allowing scanning to take place was developed. Also a dedicated MATLAB-based user friendly GUI software system for controlling the transducer, data acquisition, analysis and display was also developed to work with the hardware.

With reference to Tasks 2.4 and 2.5 lab-scale testing of the ultrasonic NDT/NDE hardware and software were undertaken (in conjunction with equipment developed in WP3 and WP4) in order to see how the system performed whilst scanning a variety of materials (CFRP, GFRP, different thicknesses etc.), with the aim to identify potential problems and incompatibilities and a number of changes and modifications resulted from this work.

A number of tests were carried out using the automated inspection device on CFRP and GFRP at a variety of thicknesses. Tests were carried out on 5 and 12 mm carbon fibre plates in order to test the system. The system found the known defects in the plate and that they are easily identifiable when compared with the baseline readings of the CFRP plates. Further tests were then carried out on 4 and 8 mm thick GFRP samples in order to get a better idea as to how the system will perform on a wind turbine blade sample. The probe successfully acquired the data on both thicknesses of glass fibre plate. Tests were carried out in an attempt to identify defects on the inside of a blade sample. The data showed that it is possible for the system to locate defects inside a wind turbine blade; however, the optimal settings should be used. Although the systems performance was lower when attempting to find defects inside a blade than on the surface, it is expected that most of the defects which the automated device will encounter will be on the outside of a blade rather than inside. This shows that the device should be able to identify defects on wind turbine blade samples with some optimization and multiple-scans from either with a front surface scan or a back surface scan.

After the scans were conducted it was clear that the automated inspection device performed well, however it is possible to add further improvements. The suction cups currently used to hold the device are performing well, but could be made larger and with a greater pivot. This would allow the device to adhere to more extreme surface curvatures and grades of roughness. If the suction cups were to be changed then there could be an impact on the mounting brackets, which would need to be manufactured wider to accommodate the width of new the cup. The air supply too would have to be investigated as a larger suction cup would require a larger quantity of air to generate a vacuum.

Other considerations which could be made in the future include the possibility of further reducing the weight of the automated device by reducing the amount of metalwork used in the frame. The lighter the device is, the longer the suction cups would be able to hold the device against the blade without requesting additional airflow. The cabling could also be consolidated into as minimal as possible and a gimbal installed behind the probe to allow the probes surface to better track the surface of the turbine blade.

In this deliverable, we have reported on the work successfully completed to demonstrate the sys- tem developed is capable of detecting defects on samples in laboratory scale testing and also with a large sample of a wind turbine blade on the ground that incorporated typical defects that would be found on a ‘working’ turbine blade. These are described more fully in Deliverable D2.3.

WP No. 3: The work done involved the evaluation of the currently available tooling for composite cutting (Task 3.1) and was reported in PMR1/Deliverable D3.1. A second Task within WP3 was Task 3.2 Optimisation of laser parameters. In this regard the main laser parameters (power, laser frequency, energy requirements, pulse duration and repetition frequency, spot diameter, etc.) were looked at in relation to the GFRP and CFRP composites used in the manufacture of wind turbine blades. Extensive theoretical and experimental evaluation of the effect of the above laser parameters on the surface processing was performed, in order to achieve the best results for the range of materials most usually faced in turbine blades. Attention was also paid to the minimization of heat penetration into the material and potential delamination. Moreover, the requirements for an automated laser device for cutting and grinding processes were examined bearing in mind the constraints set in WP1 (magnitude, weight etc.), as well as cost constraints.
With regard to the above work, it was established by testing on GFRP (10mm thick), the energy absorption in UV-spectrum was about 92 - 95 %; this would drop significantly in the NIR-range (approx. 79 %) and visual spectrum (approx. 63 %). This enabled us to conclude that UV-laser would be best for Laser cutting of a damaged surface. However, in order to evaluate the influence of absorption on the possible processing results, preliminary trials involving four laser sources were performed. The four laser sources are summarised in the table 1.
The processed surfaces were evaluated with visual inspection. Criteria for the quality of the laser ablation process were ablation of fibres, the development of Heat Affected Zones (HAZ) and the smoothness of the created surfaces. It was apparent from results for laser ablation varied significantly between the different laser sources. Early on, it was possible to rule out the NIR and MIR lasers, and the results from UV and VIS-Laser indicated clearly the best outcome was from the UV laser (figure 3).
Having established which laser to use, a laboratory laser system (UV laser, guiding mirrors, collimating lens, focusing lens) was setup to evaluate GFRP and CFRP material (while GFRP is still the predominant blade material, manufacturers have begun to consider CFRP too) under various processing parameters/conditions (please see deliverable D 3.2 for full details). Depending on the focal length of the objective lens (four lenses were used in the study) in use, the scanning field ranged from 11 x 11 mm² to 315 x 315 mm². With typical dimensions for repairs in the wind energy industry exceeding these limits, it was necessary to extend this setup with a 3-axis-system. The axis-system had a range of 1m in the X direction and 0.5m in Y direction, while the z-axis allows adjusting the height of the focal plane in a range of 0.5m. Therefore, it was then possible to process significantly bigger and thicker parts than before.
Following preliminary tests, it was apparent that in principle, the UV-laser to be best for a workshop repair or production post-processing. For an on-field repair, utilising a green laser (λ=532nm) might be an option, as green lasers can be fibre-guided, but transmittable laser power needs to be determined. UV-lasers will provide a very smooth and clean surface within long processing times; however they can only be mirror-guided and therefore are not applicable in an in-situ repair environment, but utilisable for post- production or workshop repair. On the other hand, green and NIR lasers produce rougher and less clean surfaces within shorter processing times than UV-lasers. Both green and NIR lasers can be fibre-guided, therefore they could also be utilised in an in-situ repair, if space and weight of the laser can be handled. It was also concluded the CO2-lasers, emitting in continuous wave mode, are not suitable for repair, while pulsed CO2-lasers might work, however this needs further examination.
Furthermore, though the experiments showed that UV-laser ablation can be used for scarfing glass fibre reinforced plastics (GFRP) at high quality but very low speed, there are some additional major challenges to overcome in order to allow an industrial application. First of all, the machinery requires a lot of space and weight bearing capability. The UV- laser machine used for the experiments consists of a laser head, laser control and water- cooler. Additionally, a laser scanner with power supply and a computer for process control would be required. Also the low average power available on such lasers, influences the processing speed (low power equates to low speed). With the approximately 30W of average laser power, the used UV- laser and similar systems available on the market cannot compete with conventional milling equipment. Finally the cost of such equipment will prohibit their use for wind-turbine blades (two orders of magnitude difference between lasers and the semi-automatic mechanical process equipment).
Although it was calculated that every hour of reduction of repair time would directly save approximately 600€, from experimental results and even accepting the quality compromises, repair time is expected to be significantly increased, rather than decreased using laser surface processing compared to mechanical milling of composite blades. However, developments in the UV-laser industry will eventually lead to more powerful machines, which would then allow an up-scaling of the process.
In the light of these results and conclusions, table 2 below is a summary of what can be reasonably expected from Laser processing, though for onsite repair it must be concluded currently laser processing is not a viable solution over mechanical surface preparation.
The development work done (laser system optimisation and process development) on laser cutting of the damaged area i.e. surface preparation for the repair showed that the laser though is a promising technology for the processing of composite materials used in wind turbine industry, is at least for the time being due to the existing constraints, in terms of cost, time and safety, especially for the case of in-situ applications, is not ideal for surface preparation of the damaged area for repair. Therefore and in order to successfully complete this project, NTUA in cooperation with GMI and the rest of partners, decided to proceed with the development of an alternative processing method, which would enable improvements of wind turbine repair technology within the framework of existing technological and market conditions.
In this regard Commercial-Off-The-Shelf (COTS) equipment used mainly in the aerospace industry was adapted for ‘in-situ’ wind turbine blade repair thereby addressing a modified Task 3.4. Sections 7 and 8 of the deliverable D3.3 has a full description of the laboratory tests done (Task 3.4) with photographs of the CORETO developed tooling in action i.e. preparing the defect area for repair. This is contrasted with the existing tooling (please see images in section 9 of D3.3) which clearly illustrates the merits of the CORTEO tooling.
The second stage of the repair involved using the newly developed ‘Combined heating–vacuum bagging’ system. To validate the equipment and methodology as been applicable to ‘REAL’ blades i.e. blades in current use as opposed to a scaled down demonstrator blade, we chose to do this work mainly on ‘REAL’ blades (a deviation from the DOW but is a better approach to demonstrate to our end users of the new process and equipment). This approach allows us to verify and validate the tooling as close as possible to real life applications. Having tested the equipment and the processes both in the laboratory and in in-field conditions, it has proven to be very efficient for a wide range of repair applications, as described in deliverable D3.3.
WP No. 4: The main achievements and work done in this WP tasks were associated mainly with the development of combined heating and vacuum bagging tooling for damage repair. This involved ‘Evaluation of existing heating methods for composite repair’ (Task 4.1) which was carried out and reported in Deliverable D4.1. This evaluation included both well-developed heating methods, such as heating blankets, as well as methods currently under development in the field of aeronautics, such as the induction heating. Finally, the potential of applied vacuum bagging methods was evaluated, in order to arrive at a combined heating and vacuum bagging tooling.
In carrying out Task 4.2 (Development of special heating blankets and induction heating equipment) and Task 4.3 (Development of combined heating and vacuum device), we have developed heating blankets customized for heating different areas of the blade and a combined heating – vacuum bagging device, which greatly facilitates in-situ repairs of wind turbine blades (see Deliverable D4.2). Examples of existing heating blankets are shown in figure 4 and figure 5 shows a new large conductive heating blanket developed for this project. Figure 6 is a drawing of a combined heating and vacuum blanket with measurements and thermocouple position locations.
It was evident, the heating control (for these heating and vacuum blankets) such as ANITA used in aeronautical repair would be prohibitive by the weight and volume to use with onsite wind blade repair. Therefore, efforts were focused on the development of appropriate conductive heating equipment and a robust, “push-button” conductive heating console (figure 7) was developed for use in in-situ repair of wind turbine blades. Effort was expended to make such equipment as simple as possible, in order to ensure ease of operation and durability.
This concludes the development of the heating blankets, customized for heating of different areas of turbine blades. The blankets were powered by specially made hot bonding consoles, with a high degree of automation. The combined heating and vacuum bagging that was developed greatly facilitates the in-situ repair of wind turbine blades. Such equipment will enable simple and fast operations, while achieving the set requirements of quality. The above mentioned developments are described within the Deliverable D4.2. It is expected that, through the application of these developments to in-situ wind blade repair, a significant gain in time will be achieved thereby reducing the overall repair cost and downtime.
This WP concludes with individual and combined lab scale testing (Task 4.4 and 4.5) of the new ‘combined heating and vacuum bagging’ system. This system as shown above consisted of the ‘Conductive’ heating console, customised power supply, heating blankets, the vacuum bagging and equipment and other accessories (shown in section 5 of D4.3). Having tested the repair with different sizes of heating blankets (figure 4); this reflects repair of small to large defect areas (Task 4.4) the main work was carried out with ground testing i.e. in-field testing (Task 4.5). This work is illustrated in deliverable D4.3 and is not replicated here but to say after some modification following laboratory tests, ground testing was successfully completed with a ‘REAL’ wind blade and the following positives were noted:
a. Significant reduction of the overall time required to install the vacuum bagging equipment, the heating blanket and the thermocouples, in all examined cases.
b. Enabling of “vacuum attachment” of the combined equipment to wind turbine blades (i.e. without the need for additional attachment straps), which is extremely useful for the case of in-situ repairs (i.e. on vertical blades)
c. Reduction of the human-induced errors, through easier to follow instructions and procedures.
d. Significantly better process control, through innovative developed temperature control algorithms installed in the power supply & control equipment.
e. Enabling of quality control and certification of the repair, through the inherent capability of the power supply and control equipment to provide detailed recordings of temperature and vacuum versus time.
WP No. 5: The aim of this WP is to develop a wind turbine blade demonstrator, on which the developed equipment and processes can be tested, improved upon and adapted for ground testing (please note that the emphasis here is the proof of concept of the tools and processes for in-situ damage repair and not to demonstrate the repair while the blade is attached to the nacelle, as this would require a special platform etc.)
In Task 5.1 a real scale demonstrator, in other words a scaled down blade (part of a full blade) with real defects that have risen while the blade was in active use was obtained. In order to be fully representative, we have ‘insert’ defects that were not present in the original demonstrator blade so as to demonstrate the equipment and techniques developed as been applicable for any eventuality i.e. as many defects that might be present in all blades in the field. A number of photographs of the blade with defects are shown in deliverable D5.1. The photographs show important aspects of the blade where defects are; these are the varying thickness of the blade (can be seen from the cross sections) and the structural material differences. Following the building of the demonstrator (i.e. having a selection of representative defects) in Task 5.2 testing of the developed equipment was carried out. This is in two parts, first the identification of the defects using ultrasonic techniques and the repair of the identified defects. With regard to the first, testing showed that with the use of ultrasonic probe mounted on a holder which in turn is mounted onto a large frame that is then placed on the blade and held by vacuum allowed scanning (X-Y-Z) of the blade and defect detection. This ultrasonic system (hardware and software) was successfully demonstrated in the detection of defects already present and inserted into the blade. This is reported in deliverable D2.3. With regard to the repair element of the detected defects, it was decided to demonstrate the capability of the repair technology by using a ‘REAL’ blade (the demonstrator was not used) that will most likely be re-used. This approach was considered to be more valuable in the longer run. In this deliverable D5.1 (section 3) images of the repair are shown, but a fuller account can be found in D5.2.
In conclusion the CORETO surface processing tooling using COTS equipment and methodology developed as an alternative to Laser processing have been successfully tested in the laboratory, on the scaled demonstrator blade and on a ‘REAL’ blade. We have also demonstrated (see D5.2) the advantages of the CORETO processing over the existing methodology and tooling.
WP No. 6: The activity in this WP is mainly to do with the dissemination of the project progress, technology development and exploitation of the project results. Furthermore it was envisaged that the project ‘innovations’ to be passed onto the SMEs to take advantage of the technology and thereby derive an economic benefit. In this regard the technology developed was to be marketed to potential customer in the wind energy sector and where the technology is applicable to other industrial sectors, non-wind energy customers were also to be actively approached. The rail industry is such a potential customer, as rail lines and rolling stock can be monitored with NDT and composites on rolling stock repaired with the CORETO developed technology.
This WP consists of 3 Tasks (Task 6.1: Marketing Strategy Development, Task 6.2: Awareness events and conferences and Task 6.3: Advertising and promotions) and has eight associated deliverables. In this regard a Website was development; the website has 5 main sections and these are described in the deliverable D6.1.
One of the most important tasks in this WP is the ‘Plan for the Use and Dissemination of Foreground’. In Deliverable D6.2 and D6.8 (update of D6.2) we describe the knowledge management, dissemination, exploitation and use of IPR, having established what foreground IP has arisen.
Another task within this WP is Task 6.2 (described in Deliverable D6.4); this task involved a formal presentation and demonstration (Awareness Seminar, D6.4) to the SMEs in particular by the RTD’s on the work carried out in the project. A video of this Awareness Seminar was made to highlight important aspects of the project work (D6.6).
In deliverable D6.3 and D6.5 (update of D6.3) we highlight the main activities relating to Press releases (posters and flyers), publications in particular in the World Wind Technology magazine and the conference paper at the 7th European workshop on structural health monitoring. The consortium also participated and attended at a number of other conferences. Finally a Wikipedia page has been written, some difficulties was experienced with this (D 6.7) and the Wiki information had to be posted at the NDTwiki.com.
Efficient use and dissemination of knowledge (foreground) is a fundamental activity in any research process, since the success of these dissemination activities contributes decisively to the short and long term success of a research project – as measured by knowledge usage by external entities and degree of adoption in the industry. Addressing this, is the main thrust of this WP6 and in this regard the PUDF sets out the details of the types of dissemination activities that were undertaken during the project lifetime, focusing on the target group, the SMEs within this consortium and Europe wide. In this respect, the consortium was well placed because of the diverse background of the participating partners, which included long term experienced specialists, international research institutes and numerous progressive SMEs who are active in this field. It is important to say that the diversity allows us to exploit the technology developed not only in the wind sector but in other arenas.
We have in addressing the strategy to be used for the PUDF detailed how the PUDF will be managed. A number of tasks that would need to be carried out along with the role of the partners in this dissemination and exploitation were identified and actioned. A number of communication tools that would be used in the dissemination and exploitation were also discussed and used. These being:
• Websites
• Publications
• Presentation, Courses and Training
• External Resources

Also outlined was what we envisage as been available for dissemination and exploitation (Technology Readiness Level, TRL and Exploitable Knowledge) and how these can and should be disseminated and exploited during the project and after completion of the project.
The main outcomes from the work in WP6 are:
• The creation of a website (dedicated project website and partner websites): A computer version and a mobile version have been created. All the partners have created a direct link from their own university/company websites to the CORETO website
• The creation of Posters and Flyers
• The publication of articles in specialized magazines such as ‘The W orld W ind Technology Magazine’
• The participation in conferences during important events such as 7th European workshop on structural health monitoring
• The realization of an Awareness Seminar held at GMI AERO on the 27th of March, 2014

A full list of conferences and workshops that partners in the consortium participated is given in D6.8 section 4.3.1. In 2012, the consortium participated in 9 public events and in 11 events in 2013, followed by 5 events in 2014; together the consortium in the course of the duration of the project participated in 25 conferences and workshops.
In addition to the 25 dissemination activities, the consortium disseminated the progress and outcomes of the project through 3 publications and conference papers and another is in preparation for the 7th European Workshop on Structural Health Monitoring to be held in Nates in July 2014 (section 4.3.2 of D6.8). To enable further marketing and communication to the wider audience a poster and a flyer were constructed, displayed and distributed (the poster and flyer can be seen in Appendix 3 and 4 respectively in D6.8).
An important aspect to the possible commercialisation of the developed technology is to determine the Technology Readiness Level (TRL), the analysis of the Strengths, Weaknesses, Opportunities and Treats (SWOT) of the developed technology; this is reported in Section 5 of D6.8. Further activity that important from the user/SME perspective is a good appreciation and hands on experience of the developed technology. In this regard the RTD’s held a ‘Awareness Seminar’ at GMI Aero facility in Paris on the 27th of March this year (D6.4) and made a Video of the demonstration of the tools, its use etc. This latter is described in D6.6. Finally, with commercialisation in mind, the intellectual Property Rights (IPR) was discussed (Figure 10 and Table 1 of D6.8).
The consortium in moving forward from the end of the project aims to exploit the key advantages of the CORETO outcomes; these being:
• Cost efficient - Existing solutions require (in most cases) the disassembly of the turbine blades and shipping to specialized composite repair facilities, which results in increased downtime and loss of income. Appropriate tooling developed during CORETO project are available to enable in-situ repair of turbine blades, large-scale reductions could be achieved (both in terms of time and money)
• Repair quality and repeatability increased - The human impact on the repair is reduced as some steps of the repairing procedure are automatized (NDT inspection for example). Automation increases also the repeatability of the repair quality due to the limitation of human impacts
• Security improved - The repair procedure improves the security of the operators as the manual operations are limited compared to the existing procedures. The increase of the wind turbine blades dimensions and their location (off -shore particularly) generates important risks for operator during maintenance operations which are significantly reduced
• Standard solution - The repair tooling is able to manage the needed maintenance on most of the wind turbine blades existing today
• Repair traceability - The inspection system developed can save and store all the repair parameters and ensure a good traceability of the maintenance realized on the Wind turbine blade
• Other non-Wind Applications - It is also envisaged that the technology can be used in other sectors of industry where NDT and composite repair is required e.g. Rail rolling stock

WP No. 7: The work progress in this WP, involved the project management; a close ‘day to day’ management of the project was undertaken by the project coordinator and progress reports (technical deliverables and Consortium Grant Agreement (D7.1) and other reports (PMR1, 2, Final report, Form C etc.) were scrutinised and uploaded to SESAM (ECAS).

Note: Tables and Figures attached.
Potential Impact:
The broad aim of the CORETO project was to address the potential wind turbine blade failure; in the past lack of maintenance of blades has led to catastrophic failure leading very high cost of replacement, repair, loss of production and even injury to property and personnel. It is thus crucial to maintain wind turbine blades regularly, due to the high stresses they experience under high loads and varying environmental conditions.
Conventional methods of blade repair require once defects have been identified to ship the blades to a workshop off-site for further inspection and then repair. This is undoubtedly extremely time-consuming and costly.
The work in this CORETO project can basically be divided into two, the defect detection and repair. With regard to the first our work investigated the use of pulse-echo ultrasound to detect internal damages in wind turbine blades without the necessity to ship the blades off-site.
With regard to the detection, a 2D ultrasonic NDT system consisting of software to control the automated scanning and show the damage areas in a 2D/3D map with different colours so that the inspector can easily identify the damage areas has been developed and optimised for in-situ wind turbine blade inspection. The system is designed to be light weight so it can be easily carried by an inspector climbing onto the wind turbine blade for in-situ inspection. It can be operated in 1D A-Scan, 2D C-Scan or 3D Volume Scans. Experiments on Glass Fibre Reinforced Plastics (GFRP) and wind turbine blades (made of GFRP) samples showed that in addition to surface damage, internal defects can be detected. The main advantages of this system are the fully automated 2D spatial scanning and flaw displaying. It is potentially to be used for in-situ inspection to save maintenance time and hence considered to be economically beneficial for the wind energy industry.
For the second part, the original concept was to develop a laser system to prepare the defect area for repair; having established that the laser system is currently for reasons already discussed not applicable for in-situ repair, we used ‘Commercial-Off-The-Shelf’ (COTS) equipment which is mainly used in the aerospace industry and adapted them for ‘in-situ’ wind turbine blade surface preparation. Following surface preparation a ‘Combined Heating and Vacuum Bagging’ with heating blankets designed for small to large defects areas and novel conductive heating was used for the final repair.
What is the foreseen impact that the CORETO technology will have? It is known that most rotor blades carry post-installation warranties of only one or two years. On the other hand the expected service life of a blade is 15 to 20 years; this leaves much of the blade’s maintenance outside the warranty window. It is said that at the end of 2011, the warranties of 25,000 turbines or 75,000 blades would have expired and the warranties on another 28,000 turbines (84,000 blades) would have expired at the end of 2012. Based on these sums and the wind energy boom, there are now more turbines with expiring warranties than are being installed. This is putting immense pressure on wind farm managers as they try to optimize turbine uptime. It is very apparent with such numbers long downtimes would have a large impact on the energy production and on the profits of the wind farm operators and owners. Here is the First of an impact area for CORETO partners to exploit, while the figures given is global, the European picture is proportionally similar.
Blade repair is no trivial matter. The sources of blade damage include mishandling during delivery and/or installation, lightning strikes, ice, thermal cycling, leading and trailing edge erosion, fatigue, moisture intrusion and foreign object impact. An out-of-service turbine is estimated to cost anything between 600 to 1,200 Euros per day (does not include cost of a crane etc. for getting access to the blade) and an average blade repair can cost up to 22,000 Euros, while a new blade cost is about 150,000 Euros. These figures clearly show an in-situ repair whilst the defects are at its infancy and where the maintenance can be scheduled in during a general maintenance window is what CORETO technology allows, for example the different sizes of heating blankets allow for even the smallest defect i.e. where this defect is currently a ‘low’ priority to be treated/repaired before it becomes a MUST repair defect. This begs the question why not wait till it is a MUST repair defect, the reason for this is even small defects begin to have an impact on the aerodynamic efficiency. This is Second capability and potential market that CORETO brings to the wind energy industry.
With wind turbine blade manufacture, the resin, fibre, varying ply patterns, core types, epoxy vs. vinyl ester, infusion vs. prepreg etc. are proprietary and often repair specialists, don’t have access to the original (legacy) material. Then the challenge is to find composite products (resins, fabrics, adhesives) that are equivalent to the legacy material in the blade. CORETO scores well in this regard as the successful ground and field testing with the developed technology on a number of different defects at different material areas of the blade would have encountered the differences in resin, fibre etc. that were mentioned above and the fact that we have successfully repaired these both with samples, the large demonstrator and with the ‘REAL’ blade gives us a Third impact area.
It would have been apparent from this document, periodic report and deliverables, the repair procedures revolved around a few primary functions: defect detection, preparation of the damaged site using our COST equipment, hand laydown of the thermal blankets and curing using the combined heating and vacuum blankets, followed by a final test.
Let’s look at how CORETO Ultrasonic transducer system helps; a most challenging detection is the detection of internal damage, the damage at the blade’s surface typically shows up only as minor defect, but removal of the blade skin often reveals extensive internal damage that require replacement of relatively large blade sections (this is quite typical with lighting damage). CORETO Ultrasonic NDT system is with its scanning capability able to identify the deeper ‘large’ area damage, this potentially is the Fourth market opportunity for CORETO partners to exploit.
With regard to in-situ repair, as has been said this involves surface preparation, and we have shown the merits of the CORETO Commercial-Off-The-Shelf (COTS) equipment in preparing the surface for wind turbine blade repair over traditional methods (D3.3). The comparison of the ‘New’ method, adapted from aerospace engineering with conventional repair technology (D3.3) indicates that this CORETO way is best and this is the Fifth area for that the partners to exploit.
Finally the combined ‘heating blankets and vacuum bagging’ technology with ‘conductive heating’ control (generally it is inductive heating), blankets to cover small to large defect areas and data logging is very much a potential technology area, the Sixth area to exploit with wind turbine blade manufacturers and other composite structure users.
Outside the wind industry, both the Ultrasonic NDT technology and composite repair technology of CORETO may be applied to for instance in the Rail industry for structural monitoring of rail lines and of the rolling stock which increasingly uses composites. In the railway industry Structural Health Monitoring (SHM) is of increased interest for monitoring rail tracks and sleepers, railway turnout, railway bridges, rolling stock and other components associated with the rail networks. Both our technologies with some adaption are viable for SHM monitoring and repair of railway structures. This is Seventh area of impact.
Another use of the ultrasonic NDT technology developed here in CORETO is for monitoring the Structural Health of tunnels, for example the CrossRail train development in the UK, with the deep digging of the earth for new tunnels necessitates the monitoring of the old already existing tunnels nearby that are in use for possible defects arising from digging. This is another area, Eighth for potential exploitation.
How has CORETO set about exploiting the impact areas? In order to exploit these potential markets, it is important to disseminate the CORETO project progress and outcomes i.e. the newly developed technology needs to be in the public domain. This last section describes what steps we have taken to disseminate and exploit the potential markets.
To this end, we have used a number of communication tools to help with the dissemination. These being:
• Websites
• Publications
• Presentation, Courses and Training
In this regard the following were done:
• The creation of a website (dedicated project website and partner websites): A computer version and a mobile version have been created. All the partners have created a direct link from their own university/company websites to the CORETO website
• The creation of Posters and Flyers
• The publication of articles in specialized magazines such as ‘The W orld W ind Technology Magazine’
• The participation in conferences during important events such as 7th European workshop on structural health monitoring
• The realization of an Awareness Seminar held at GMI AERO on the 27th of March, 2014
In 2012, the consortium participated in 9 public events and 11 events in 2013, followed by 5 events in 2014; together the consortium in the course of the project participated in 25 conferences and workshops allowing many discussions and networking with potential customers.
In addition to the 25 dissemination activities, the consortium disseminated the progress and outcomes of the project through 3 publications and conference papers and another is in preparation for the 7th European Workshop on Structural Health Monitoring to be held in Nates in July 2014. To enable further marketing and communication to a wider audience as possible a poster and a flyer were constructed, displayed and distributed (the poster and flyer can be seen in Appendix 3 and 4 respectively in D6.8).
It also must be said that an important aspect to the possible commercialisation of the developed technology is to determine the Technology Readiness Level (TRL), the analysis of the Strengths, Weaknesses, Opportunities and Treats (SWOT) of the developed technology; this is was done and reported in D6.8.
A further activity that is important from the user/SME perspective is a good appreciation and hands on experience of the developed technology. In this regard the RTD’s held a ‘Awareness Seminar’ at GMI Aero facility in Paris on the 27th of March this year (D6.4) and made a Video of the demonstration of the tools, its use etc. This latter is described in D6.6. Finally, with commercialisation in mind, the intellectual Property Rights (IPR) was discussed (Figure 10 and Table 1 of D6.8).
The consortium in moving forward from the end of the project aims to exploit the key advantages of the CORETO outcomes; these being:
• Cost efficiency - Existing solutions require (in most cases) the disassembly of the turbine blades and shipping to specialized composite repair facilities, which results in increased downtime and loss of income. Appropriate tooling developed during CORETO project are available to enable in-situ repair of turbine blades, large-scale reductions could be achieved (both in terms of time and money)
• Increased repair quality and repeatability - The human impact on the repair is reduced as some steps of the repairing procedure are automatized (NDT inspection for example). Automation increases also the repeatability of the repair quality due to the limitation of human impacts
• Improved security - The repair procedure improves the security of the operators as the manual operations are limited compared to the existing procedures. The increase of the wind turbine blades dimensions and their location (off -shore particularly) generates important risks for operator during maintenance operations which are significantly reduced
• Standard solution - The repair tooling is able to manage the needed maintenance on most of the wind turbine blades existing today
• Repair traceability - The inspection system developed can save and store all the repair parameters and ensure a good traceability of the maintenance realized on the Wind turbine blade
• Other non-Wind Applications - It is also envisaged that the technology can be used in other sectors of industry where NDT and composite repair is required e.g. Rail rolling stock
All in all, it is believed the foundations for commercial exploitation of the CORETO technology has been set out with essential market potential and impact identified.
List of Websites:
http://www.coreto-project.eu/