Development of a robust structural health monitoring system for wind turbine foundations

The construction of onshore wind turbines has rapidly been increasing as the UK attempts to meet its renewable energy targets. As the UK’s future energy depends more on wind farms, safety and security are critical to the success of this renewable energy source. Structural integrity is a critical element of this security of supply. With the stochastic nature of the load regime a bespoke low cost structural health monitoring system is required to monitor integrity. This paper presents an assessment of ‘embedded can’ style foundation failure modes in large onshore wind turbines and proposes a novel condition based monitoring solution to aid in early warning of failure

El impacto económico de la guerra Rusia y Ucrania

El trabajo trata de como ha sido el impacto de la guerra entre Rusia y Ucrania sobre la economía europea y rusa. Una guerra entre dos países que son importantes exportadores de productos primarios en el mundo, energéticos para Rusia y agroalimentarios para Ucrania, es de gran relevancia global. Cada día puede surgir un evento que lleve a un cambio en el comercio mundial y las relaciones entre estos países y el resto del mundoMáster en Comercio Exterio

Settlement rehabilitation of a 35 year old building : case study integrated with analysis and implementation

This paper presents a rehabilitation project concerning the settlement of a 35 year old building. The foundation system of the northwest wing of the building consists of strip footings and slabon-grade. Differential settlement results in significant cracking of the masonry partition walls located on the footing and hence rehabilitation of the footing is required to stabilize the foundation system. Geotechnical and structural investigations are conducted, including site borings and analytical modeling based on one-dimensional consolidation theory that is incorporated into a finite element analysis. The predictive model exhibits that the differential settlement does not cause noticeable distress for the primary structural members, whereas the continued settlement affects use of the building. Site implementation is performed with the pushpile method to terminate the continuous settlement of the foundation

Wind turbine foundation deburial sensors based on induction-heated ceramic patches

The deburial and scouring of concrete wind turbine and bridge foundations presents a risk to structural stability and safety. In this work, we present a novel, ceramic temperature-sensing patch which can detect whether sections of a foundation are buried or exposed to air. The sensor patches, applied to concrete specimens, were fabricated by loading a geopolymer with 0 - 60 wt% ground magnetite. The magnetite content allowed the patches to be heated using an induction coil, while temperature profiles were monitored via changes in patch electrical impedance. Sensor patches were left uncoated, or were coated in surface-water, soil and sand. Each material provided a unique thermal signature which, with simple signal processing, could be used to reliably detect whether the patch was buried

Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures

In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mε of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mε compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10−2 and −2 × 10−4 respectively. The typical strain resolution in the uniaxial sensor was 100 με. The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mε of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10−2 and 4 × 10−5 respectively. The biaxial sensor’s strain resolution was approximately 10 με in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution

Structural integrity monitoring of onshore wind turbine concrete foundations

Signs of damage around the bottom flange of the embedded ring were identified in a large number of existing onshore concrete foundations. As a result, the embedded ring experienced excessive vertical displacement. A wireless structural integrity monitoring (SIM) technique was developed and installed in the field to monitor the stability of these turbines by measuring the displacement patterns and subsequently alerting any significant movements of the embedded ring. This was achieved by using wireless displacement sensors located in the bottom of the turbine. A wind turbine was used as a test bed to evaluate the performance of the SIM system under field operating conditions. The results obtained from the sensors and supervisory control and data acquisition (SCADA) showed that the embedded ring exhibited significant vertical movement especially during periods of turbulent wind speed and during shut down and start up events. The measured displacement was variable around the circumference of the foundation as a result of the wind direction and the rotor uplift forces. The excessive vertical movement was observed in the side where the rotor is rotating upwards. The field test demonstrated that the SIM technique offers great potential for improving the reliability and safety of wind turbine foundations

Geopolymeric thermal conductivity sensors for surface-mounting onto concrete structures

In this work, we present a novel, geopolymer temperature-sensing patch which can be heated using induction and used to infer thermal conductivity of the surrounding medium. The sensor patches, applied to concrete specimens, were fabricated by loading a geopolymer binder with 0 - 60 wt% ground magnetite. The magnetite content allowed the patches to be heated using an induction coil, while temperature profiles were monitored via changes in patch electrical impedance. Sensor patches were left uncoated, or were coated in surface-water, soil and sand. Each material provided a unique thermal signature which, with simple signal processing, could be used to reliably detect whether the patch was buried

Wireless surface acoustic wave sensors for displacement and crack monitoring in concrete structures

In this work, we demonstrate that wireless surface acoustic wave devices can be used to monitor millimetre displacements in crack opening during the cyclic and static loading of reinforced concrete structures. Sensors were packaged to extend their gauge length and to protect them against brittle fracture, before being surface-mounted onto the tensioned surface of a concrete beam. The accuracy of measurements was verified using computational methods and optical-fibre strain sensors. After packaging, the displacement and temperature resolutions of the surface acoustic wave sensors were 10µm and 2 C respectively. With some further work, these devices could be retrofitted to existing concrete structures to facilitate wireless structural health monitoring

Analysis and experiment on bending performance of laser-welded web-core sandwich plates

The bending performance is the main performance index of the sandwich structure. This paper is used to analyse and test showing that: the range of the elastic limit and the maximum bearing capacity is 25~30. kN and 34.9~54.8. kN, respectively; the average of bending stiffness and shear stiffness measured by test is 810. kN. m and 1717. kN/m, respectively; In elastic stage (U2 = 6 mm), plate material in the weld junction of web (n = 5)and face plates appear local yield, which shows that the most unfavorable area of sandwich panels is the weld junction of web and face plates

Structural health monitoring for wind turbine foundations

The construction of onshore wind turbines has rapidly been increasing as the UK attempts to meet its renewable energy targets. As the UK’s future energy depends more on wind farms, safety and security are critical to the success of this renewable energy source. Structural integrity of the tower and its components is a critical element of this security of supply. With the stochastic nature of the load regime a bespoke low cost structural health monitoring system is required to monitor integrity of the concrete foundation supporting the tower. This paper presents an assessment of ‘embedded can’ style foundation failure modes in large onshore wind turbines and proposes a novel condition based monitoring solution to aid in early warning of failure. The most common failure modes are discussed and a low-cost remote monitoring system is presented