Main Menu

See All Software See All Instruments See All Transducers See All Vibration Testing Equipment See All Electroacoustics See All Acoustic End-of-Line Test Systems See All Academy See All Resource Center See All Applications See All Industries See All Services See All Support See All Our Business See All Our History See All Global Presence

Main Menu

See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All DAQ Software See All Drivers & API See All Utility See All Vibration Control See All High Precision and Calibration Systems See All DAQ Systems See All S&V Hand-held Devices See All Industrial Electronics See All Power Analyzer See All S&V Signal Conditioner See All Acoustic See All Current and Voltage Sensors See All Displacement See All Force sensors See All Load Cells See All Pressure See All Strain Gauges See All Temperature Sensors See All Torque Sensors See All Vibration See All Accessories for Vibration Testing Equipment See All Vibration Controllers See All Measurement Exciters See All Modal Exciters See All Power Amplifiers See All LDS Shaker Systems See All Test Solutions See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All Training Courses See All Acoustics See All Asset & Process Monitoring See All Custom Sensors See All Data Acquisition & Analysis See All Durability & Fatigue See All Electric Power Testing See All NVH See All Reliability See All Smart Sensors See All Vibration See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance See All BKSV Worldwide Contacts

Main Menu

See All API See All Microphone Cartridges See All Microphone Sets See All Microphone Pre-amplifiers See All Sound Sources See All Acoustic Calibrators See All Special Microphones See All Accessories for acoustic transducers See All Experimental testing See All Transducer Manufacturing (OEM) See All Piezoelectric Charge Accelerometers See All Piezoelectric CCLD (IEPE) accelerometers See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Vibration Testing with Electrodynamic Shakers See All Structural Dynamics See All Machine Analysis and Diagnostics See All Dynamic Weighing See All Vehicle Electrification See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management

FZK: loading by waves in wind power plants



HBK S9M force transducer records the loading exerted by waves on framework structures in offshore wind power plants

When waves break on offshore wind energy plants, pressure shocks are generated that can load the foundation structures of the plants in shallow water. To improve dimensioning methods in these situations for framework structures, also called jacket structures, physical modelling experiments were carried out at the Large Wave Channel of the Coastal Research Center (FZK) in Hannover, Germany. The S9M force transducer from HBK provided decisive findings.


Loading test in one of the largest wave channels in the world

Especially pressure surges caused by "plunging breakers" are critically important. There are some analytical models that describe loading due to plunging breakers on individual round poles. However, such approaches can only be applied to a limited extent to jacket structures as they are used in offshore wind energy plants. This is not surprising given the different levels of complexity in terms of hydraulic conditions. To improve dimensioning methods for framework structures subject to pressure surge loading, physical modelling experiments were carried out using a large scale model at the FZK Large Wave Channel as part of the EU research program HYDRALAB IV. The experiments were commissioned by the Norwegian University for Science and Technology (NTNU) in Trondheim and Stavanger University (UiS). Measuring 320 meters in length, 5 meters wide and 7 meters deep, the Large Wave Channel of the FZK is among the largest in the world. To make optimum use of the 800 kW output of the wave generator, the scaling of the model was defined as 1:8. The waves acting on the structure at this scaling were over two meters high. The rods in the framework consisted of steel pipes 14 cm in diameter. The dimensions of the overall structure were 2.4 x 2.4 x 4.9 m.

All loading recorded metrologically

To record the hydraulic processes and the effects on the selected jacket structure metrologically, the wave channel and the structure itself were fitted with a large number of different transducers:

  • Wave level and flow sensors measured the fluctuation in water level and flow conditions in front of and on the structure.
  • The reaction of the framework structure to wave loading was measured with force transducers and acceleration sensors.
  • A video system synchronized with measurement acquisition provided detailed visual information about the nature of the breaking waves and the wave amplitude on the structure.

The greatest challenge – force measurement

The various force measurements on the structure posed a special challenge. One task was to determine the load distribution on selected framework rods. Another was to determine the total force acting on individual rods and the force acting on the overall structure. Because the force transducers were intermittently or permanently submerged, HBK force transducers type S9M with degree of protection IP 68 were used to determine the load distribution. Up to four force transducer were placed in individual rods made of solid aluminum. Perpendicular wave loading was measured on 5-cm wide framework rings fastened onto each of these force transducers. The individual measurements were then used to determine the load distribution on a rod.

Four force transducers of the same type were used to determine the resulting total horizontal force acting on the structure. To prevent force shunts, the entire framework structure was fastened onto articulated pendulum supports and the force transducers were fitted on the four pendulum supports in the direction of the wave impact. HBK developed two-component transducers to measure the resulting forces on six selected framework rods. The six rods were integrated into the jacket structure through two force transducers each. A very compact design had to be developed due to the specified diameter of the framework pipes (14 cm) and the large forces expected (nominal (rated) lateral force of the transducer 20 kN). To prevent loading of the force transducers due to bending moments, they were fastened onto the structure with specially developed ball joints.


Coastal Research Centre (FZK)

As a joint institution of Leibniz University Hannover and Technische Universität Braunschweig, the Coastal Research Centre (FZK) stands for first-class research in the field of coastal engineering and maritime technologies. This is made possible not at least by the globally outstanding equipment for carrying out physical model tests with waves and currents, above all the Large Wave Flume (GWK). Learn more about FZK and our competence. Get in touch with us and let us research together for science or practice.

more about FZK

Technology used