With the increasing size of turbines and the deeper location of wind farms, the monopile foundations of offshore wind turbines increase in size, weight, and costs. Jackets can be an attractive alternative because multi-membered circular hollow section (CHS) support structures are lighter than monopiles. However, the complex welds result in reduced fatigue resistance of structural joints of circular hollow sections, thus higher costs and longer production routes for jackets than for monopiles.

In the project WrapNode-I, TU Delft will lead research with 9 industrial partners that will enable implementation of the innovative, bonded, wrapped composite joint in jackets for offshore wind turbines. We are forming a team of researchers to characterise and understand full-scale and multi-axial behaviour and the influence of the offshore environment on the durability of the joints. The team is led by Dr. Marko Pavlovic, assistant professor of Steel and Composite Structures.

The concept of an innovative bonded joining technology by wrapping composite material (a.k.a. Fibre Reinforced Polymer - FRP) around steel tubes is introduced as an alternative to traditional welded connections. Compared to complex welds, the load is transferred through a dedicated composite wrap and not through the small area of the weld. Fatigue resistance of joints is increased; thus, the tube wall thicknesses of the legs (chords) and brace members can be significantly reduced, resulting in up to 50% lighter jacket structures. In addition, the production time of the jacket is considerably shortened due to the possibility of prefabrication. Compared to monopiles, jackets manufactured with Wrapped Composite Joints offer a potential cost reduction of 25% to 50% for the supporting structures and reduction of CO2 footprint by 30% to 70%.

Your role in the project/team will be to investigate the influence of size effects on static and fatigue performance of wrapped composite joints. The research will rely on:

• Large-scale member/component ultimate failure and cyclic load (fatigue) experiments
• FEA validation and analysis of failure modes interaction and crack propagation in large-scale member/component experiments
• Characterisation of influence of size-effects (bonded surface area) on failure modes and crack propagation in composite materials and bonded interface

The project is realised with the support of the Dutch government, GROW consortium and industrial partners: Shell, Tree Composites bv, Siemens Gamesa Renewable Energy bv, HSM bv, Smulders Projects International bv, Enersea bv, AOC Nederland bv, BÜFA composites Benelux bv and Salzgitter Mannesmann Renewables GmbH.

Visit the project's website here.

You will gain scientific experience by working in a dedicated international team of 4-5 PhD and PostDoc researchers at TU Delft. You will develop professional experience by collaborating with a team of engineers from leading industrial partners who will support the project by developing reference full-scale jacket design, design and production of materials and wrapped composite joints specimens.

Background in terms of MSc and PhD in field of (combinations possible):

• Civil/Structural Engineering (e.g. steel structures, connections, composites/FRP structures, CHS joints)
• Mechanical engineering (e.g. ship building, wind turbine blades, offshore structures, fibreglass pipelines)
• Aerospace Engineering (e.g. composites, fatigue and structural integrity)

Required skills/experience:

• Planning and design of test set-ups, specimens and measurement plans for large-scale member/component level experiments
• Conducting and control of large-scale member/component static/cyclic load experiments
• Post-processing and analysis of monotonic and cyclic load experiments
• Non-linear FEA for failure mode and ultimate resistance analysis of large-scale structural members/components
• Writing and publishing scientific papers in top journals

Desirable skills/experience:

• Fatigue characterisation of large-scale structural members/components
• Fracture analysis of bonded connections/joints
• Failure and fatigue of Circular Hollow Section joints
• Measurement techniques using DIC, LVDTs and strain gauges
• Design and implementation of frames and mechanical fixtures for load application and BC control in large-scale member/component experiments
• Supervising theses of MSc students
• Teaching in BSc/MSc courses related to steel/composite structures

Fixed-term contract: 2 years.

Duration of contract: 2 years

Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities. The TU Delft offers a customisable compensation package, a discount on health insurance and sport memberships, and a monthly work costs contribution. Flexible work schedules can be arranged.

For international applicants we offer the Coming to Delft Service and Partner Career Advice to assist you with your relocation. An International Children's Centre offers childcare and there is an international primary school.

Delft University of Technology

Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context. At TU Delft we embrace diversity and aim to be as inclusive as possible (see our Code of Conduct). Together, we imagine, invent and create solutions using technology to have a positive impact on a global scale.

Challenge. Change. Impact! 

Faculty Civil Engineering and Geosciences

The Faculty of Civil Engineering & Geosciences (CEG) is committed to outstanding international research and education in the field of civil engineering, applied earth sciences, traffic and transport, water technology, and delta technology. Our research feeds into our educational programmes and covers societal challenges such as climate change, energy transition, resource depletion, urbanisation and the availability of clean water, conducted  in close cooperation with a wide range of research institutions. CEG is convinced that Open Science helps to achieve our goals and supports its scientists in integrating Open Science in their research practice. The Faculty of CEG comprises 28 research groups in the following seven departments: Materials Mechanics Management & Design, Engineering Structures, Geoscience and Engineering, Geoscience and Remote Sensing, Transport & Planning, Hydraulic Engineering and Water Management.

Click here to go to the website of the Faculty of Civil Engineering & Geosciences.