Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

FP6

RENEWITT Sintesi della relazione

Project ID: 508600
Finanziato nell'ambito di: FP6-SME
Paese: Denmark

Final Report Summary - RENEWITT (Development of new and novel automated inspection technology for glass reinforced plastic wind turbine blades)

Glass reinforced plastics (GRP) are used extensively, in the production of blades for wind turbines, because they re lightweight and corrosion resistant. One major issue in the use of this material was the lack of testing techniques suitable for the rapid and accurate inspection of large areas. The development of non-destructive testing (NDT) techniques was essential to allow European wind turbine blade (WTB) manufacturers to successfully employ the most desirable materials to achieve lightweight designs that can maximise the efficiency of the components and provide competitive advantage over the non-European manufacturers.

The scientific and technical objectives of the project were:
1) to significantly develop and improve NDT techniques, in a step change to their current capability, in order that WTB defects such as zero volume unbonds are detected early in the manufacturing process;
2) to deliver NDT techniques, optimised for use on the prototype equipment developed;
3) to conduct inspections faster and hence reduce installation downtime by automating NDT techniques;
4) to increase accuracy, by eliminating operator subjectivity and increase safety and reduce instances of failure.

The project was divided into the following stages:
- the types and sizes of defects and the structure they were likely to occur in were identified;
- samples of such structure containing realistic artificial defects were designed and manufactured;
- radiographic, shearographic, ultrasonic and thermographic inspection techniques were devised to detect the defects sought;
- hardware was developed to enable the application of these techniques on the samples previously manufactured;
- a robotic scanning system was designed and built capable of carrying the NDT systems developed;
- the NDT systems were integrated with robotic scanner;
- a programme of trials on large blade samples was carried out to test functioning of the hardware and software.

The project resulted in the following main achievements:
- A set of samples was designed and produced covering all the main types of structure of interest. Artificial defects were produced in the samples to mimic the types and sizes of defects sought.
- A digital radiography system was designed and built.
- A dual laser shearography system capable of separately resolving in-plane strain was developed and produced.
- A pulsed thermography system was built using an advanced flash excitation system. In addition, a lighter version was developed capable of using hot air excitation.
- An ultrasonic technique known as continuous wavelet transform was developed. This allowed relatively low frequency probes to be used whilst preserving near surface resolution.
- A phased array ultrasonic system capable of rapid, large area coverage using very little water was developed.
- A robotic scanner capable of carrying and controlling the above systems in order to inspect all areas of a wind turbine blade surface was designed and built.
- The above systems were integrated with the scanner to produce the RENEWIT wind turbine blade inspection system.

A set of samples was designed and produced covering all the main types of structure of interest. These included representative, full width sections of blades containing real and artificial flaws, sections of the leading and trailing edges of the blades, and GRP coupons containing controlled levels of impact damage. The flaws represented included lack of adhesive in glue lines, barely visible impact damage (BVID) and kissing bonds. Additionally a full width sample of blade weighing over 300 kg was shipped to the robotic scanner developer, where it was vertically mounted in a custom designed stillage.

X-ray Compton back scattering a NDT technique, and is carried out by measuring the amount of scattered soft X-rays from the test object. The prototype was designed to record scattered X-ray counts as a function of position of the detection volume related to the sample, f(X, Z).

Conventional shearography, using a single laser, is sensitive to out of plane strains in component. It is thus good at detecting disbands in a composite component. A novel, prototype twin laser system was developed, which was able of isolating in-plane and out-of-plane components of strain and thus being able to detect delaminations, cracks and disbands independently.

A pulsed thermography system was developed. The system could be used with powerful flash lamps to heat the surface over a short space of time for rapid inspection in a stand alone mode, or using active heating from a heat gun and a highly sensitive thermal camera. This resulted in a much lighter system able tobe integrated with the robotic scanner and used simultaneously with the other NDT systems developed.

An ultrasonic technique known as continuous wavelet transform was developed. This allowed relatively low frequency probes to be used, as required by highly attenuative materials such as those found in wind turbine blades, whilst preserving near surface resolution.

A phased array ultrasonic system capable of rapid, large area coverage using very little water was developed. It had a scanning phased system utilising a 128-channel pulser receiver system that was capable of generating beams from up to 32 active channels.

A light weight, robust scanning gantry mechanism was developed. The system was intended to deploy the developed NDT methods on a stationary wind turbine blade when positioned on the vertically moving external maintenance elevator.

The Z axis arm used pneumatic actuators to ensure a constant contact pressure with the turbine blade surface. Proximity sensors were able to detect when the blade edge was reached and stop or start scanning as required.

The end effector was vital to the operation of the system. It maintained the correct orientation of the ultrasonic probe with respect to the surface of the blade and delivers coupling water to the correct side of the probe depending on the direction of the scanning.

The planet gearbox was designed in order to enable the use of inspection tools that need to be deployed at an angle normal to the surface but were non-contacting or must maintain a significant separation.

The versatile robotic scanner was controlled by a custom designed man-machine interface. The RENEWIT scanning system combined the advantages of the shearography, thermography, ultrasonic and robotic sytems.

The RENEWIT project developed a fully automated, multi method system able to reach all areas of the blade and operable by a single operator, that with further commercialisation, could provide a cost effective maintenance solution capable of being deployed on a variety of maintenance elevators.

Informazioni correlate

Reported by

INNOSPEXION APS
KISSERUP, HVALSO
Denmark
See on map