Work Package 4





4.1. Modelling, design and manufacture of novel blade structural inserts.

Lead Partner: UoH, Co-Partners: DU, UoS (DRG)/SGRE.


To investigate how novel structural elements and materials incorporated into blades can improve mechanical properties while reducing weight and/or cost. Current blades are composed of a fibre glass and resin shell with balsawood structural elements in key locations. This project will investigate the potential for more sophisticated structural elements such as foams, honeycombs and biomimetic structures which can maintain or improve blade stiffness and impact resistance with reduced material weight and cost. The choice of materials used in these structural elements and their compatibility with current blade manufacturing processes will be evaluated. Activities within the project will include: i) adaptation of the VOX-FE2 software (very large-scale voxel-based finite element software with adaptive remodelling capability developed for bone modelling but applicable to other complex load/structure interactions running on Hull’s new HPC facility: Viper) to accommodate anisotropic material characteristics; ii) optimise and evaluate a range of material/shape combinations for use as structural elements within blades; iii) assess compatibility of proposed material/shape combinations with current blade manufacturing processes including manufacture of inserts (potentially using 3D printing) and inclusion into blade casting.

Key deliverables:
Evaluation of novel material/structure combinations for blade inserts and associated manufacturing routes. Tools to support design and evaluation of complex blade structural elements.

4.2. Embedded sensors for whole lifetime structural monitoring of blades.

Lead Partner: UoH, Co-Partners: DU, UoS(DRG)/SGRE.


To integrate fibre optic sensors into the structure of the blade to enable monitoring of manufacturing process parameters and the real-time structural health of the blade while in operation. The operational life of a blade depends on the process parameters used during manufacturing and as its in-service loading. Currently it is not possible to have real-time monitoring of manufacturing process parameters such as temperature and resin flow rate distributions, residual stresses and glass transition point. This project will investigate if it is possible to directly measure or infer these parameters in order to give operatives real-time feedback on the quality of the cast and to inform future improvements to the process. Using the same fibre-optic sensor array to monitor both manufacturing processes and operational loading makes the increased manufacturing complexity more justifiable and provides more consistent information to inform a ‘digital twin’ of the blade. This task will assess the viability of using embedded fibre optic sensors as a cost effective method for monitoring blade manufacturing processes, and for monitoring the multiaxial stresses and impacts experienced by a blade during transport, installation and operational life. Fibre optic sensors are ideal for this application since they permit cost effective distributed sensing of both thermal and multi-axis mechanical stresses but the key challenges remain of reliably embedding the sensors during manufacture and of discriminating between sensed variables while eliminating background effects. This project will interact with WP 2.3 in that the most appropriate placement of fibre sensors within blades will be determined in WP2.3 and the data generated using these sensors during operation will be analysed in WEP2.3. WP 4.2 will focus on the manufacturing processes for embedding sensors and the extraction of manufacturing process parameters. Initially sensors will be embedded and evaluated in scale blades but, if successful, full size blades will be produced by Siemens for field trials. The researcher will be responsible for identifying suitable fibre optic sensing systems and developing techniques to extract useful manufacturing process data while the Research Fellow will concentrate on techniques for integration of sensors into the blade manufacturing processes.

Key deliverables:
A robust manufacturing process which will allow the integration of multifunctional fibre-optic sensors into blades. Analysis techniques and software to extract real time manufacturing process parameters from embedded fibre optic sensors.

4.3. Mechanics of lightweight inter-array cables for offshore renewable installations.

Lead Partner: DU/Ørsted; Co-Partner: UoS (DRG).


Particular issues exist with the installation of lightweight cabling for offshore renewables installations, e.g. inter-array lines in certain seabed conditions. Cabling made using low specific gravity materials such as aluminium is often difficult to bend into place in a trench in which the seabed deposits are effectively fluidised due to the trenching operation. The initial stability following installation is then affected by soil settlement above and around the cable, and by vibrations transmitted along the cable. It is currently very difficult to predict behaviour and new tools are needed to avoid problems in the future.

Key deliverables:
In this project, numerical techniques will be developed to model the installation and post-installation of a single representative cable in a soft seabed material.

4.4 Numerical modelling of drag anchors for cable risk assessment.

Lead Partner: DU/ Ørsted.


Current approaches to determine drag anchor behaviour when assessing the risk to windfarm cables of the anchoring of vessels close to the cable route are often based on outdated anchor penetration models and data from trials undertaken many years ago. Concerns exist that for some types of seabeds the guidance, on fluke penetration and drag length, could be overconservative. Knowledge of the performance of drag anchors is necessary to assess the risk of damage to cabling laid on or in the seabed. Increasing numbers of offshore installations for renewable energy means increased cabling to carry the electricity to land and hence prompts the need for improved risk assessment procedures. In this project, advanced numerical modelling will be applied to the problem of drag anchor embedment in the seabed. The numerical modelling will be based on the Material Point Method, which provides an efficient means to model very large deformations and is ideal for the modelling of soil-structure interaction. The supervisors at Durham have already developed the method to model seabed ploughing.

Key deliverables:
The aim is for the modelling results to lead to improved quantification of risk to assets such as cables.