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Mistras Group: Blade Monitoring and Repair

In WindEnergy Network # 49, a special about our member, Mistras Group, appeared. Below the article.

Mistras group has many years’ experience worldwide, in the field of inspection and integrity monitoring of different structures during their development including structural testing and implementation.

This has been achieved with many different technologies but specifically Acoustic Emission, which is a passive material monitoring approach looking for active material damage. Mistras has championed this technology since the 1970’s providing industry leading equipment and services. The application of this skill set has been extended to include the monitoring of wind turbine components during development and operation. One particular area of interest within the industry has been blade monitoring.

Extensive testing
New designs of blade are extensively tested by the application of static and fatigue loadings in test condition. The application of Mistras AE instrumentation to monitor this process has been used to detect and locate damage to the blade structure real time, as it occurs. This provides important information on the exact point in the lading cycle, and location on the blade, the damage initiates preventing the failure of the blade in some situations. This information can be fed into the design process to allow improvements to be made.

The monitoring instrumentation has also been detecting damage to static onshore and offshore assets for more than four decades. AE Technology and as instrumentation cost and size have reduced,  so MISTRAS’ Structural Health Monitoring systems add the possibility of real-time blade monitoring during operation becomes a reality.

Cost challenge
The main challenge in live blade monitoring is one of cost, which prevents the installation of large numbers of sensors, and has hitherto limited the application to the monitoring of ‘known’ problem areas. It is nevertheless possible on certain designs of blade to provide a reasonable degree of monitoring through the careful selection of sensors and full understanding of the acoustic behavior of the blade.

This provides the potential for damage sources such as impacts, fracture, erosion and cavity breach to be detected in an economic and non-intrusive manner.

Prolonging operational life
The systems can help protect and prolong the life of a windfarm with an array of asset protection solutions; all while saving costs by avoiding high-priced repairs, detecting potential issues in their infancy and prescribing preventive maintenance.

Service combinations through experience
One-of-a-kind combination of services, technology solutions and monitoring can be offered by Mistras as a leader in traditional energy fields such as refineries, offshore oil rigs, nuclear and fossil power plants and industries like aerospace and civil infrastructure.

As wind power usage and the overall size and importance of wind turbines continue to grow and wind power farms continue to make their way offshore, these combinations in service will ensure successful operations and therefore reductions in costs.

Keeping the blades turning
The Group’s wind technicians have one goal – keep the blades turning. The Wind Team offer comprehensive solutions through a combination of inspection, preventive maintenance and repair. Preventive maintenance and inspection are essential to maximise asset lifespan, asset integrity and return on investment. The team can also be deployed quickly to respond to acute problems like lightning damage.

As a worldwide leader in one-source asset protection solutions, the group has the technology, solutions and experience to support your wind power operations in every phase. Inspection and maintenance of wind turbines from their industry-leading services team, which includes rope access and blade experts, help to eliminate costly outages and extensive repairs. Not having to rely on lifts or cranes enables the technicians to complete work efficiently and economically.

Dual-function technology
Industry-unique dual-function technology uses Vibration and Acoustic Emission analysis to detect turbine failures at their earliest stages. 24/7 wireless on-line monitoring technology provides a watchful eye on critical system components with the constant development of new monitoring concepts including web-based asset condition monitoring systems to illustrate fault warnings, alarms and diagnostics from fleet level all the way down to site level.

Inspection, maintenance and repair – the detail
Inspection – performed using visual, camera or advanced NDT methods with findings delivered in electronic format. Inspection includes thorough assessment of blade condition, tower weld integrity, composite materials and lightning protection systems; identification of potential issues; root-cause analysis; and repair recommendations through a QA Team.

Repair and Maintenance – with ten years of experience, wind specialists can make repairs that prolong the lifespan and overall effectiveness of the asset and can fix damage caused by production faults; leading edge erosion; bond-line failure; moisture intrusion; installation and lightning damage and coating defects.

The MISTRAS Group is currently working alongside some of the industry’s leading blade experts to develop solutions for the LEP – Leading Edge Prevention and Protection.