PhD scholarship in Mitigation of Sandwich Debond Damages for Robust Naval and Aircraft Structures

The Department of Mechanical Engineering, Section of Solid Mechanics at the Technical University of Denmark seeks a candidate in the Lightweight Structures group for a 3-year PhD position within “Mitigation of Sandwich Debond Damages for Robust Naval and Aircraft Structures”. The position is funded by the Office of Naval Research - US Navy and the Danish Ministry of Defense, and is one of two PhD projects within a larger research project, where the second PhD project is anchored at University of Genova, Italy. A close cooperation between the two PhD candidates will be a cornerstone in both projects.

In order for Navies and Air Forces to meet future challenges associated with both increased operations in the newly accessible arctic zone with surface vessels, as well as new improved and reliable aircrafts, light, robust and efficient naval and aircraft structures are needed. Such structures must be able to operate at both ambient and extreme cold environments, combined with impact events with floating sea ice and harsh sea conditions, or blunt impacts during operation, e.g. from bird strikes.

Composite sandwich structures have proven to be a very efficient structural concept for naval and aircraft structures, but damage tolerance under extreme environments, for a range of sandwich material configurations, is a key parameter to ensure sufficient robustness and structural integrity against service-loads and damage incidents. Based on improved insight and knowledge from a parallel on-going PhD project in the Lightweight Structures group, focused on impact related damages and the associated face/core debond damage nucleation and subsequent fatigue growth mechanisms, a novel face/core interface propagation and kinking fatigue mitigation concept must be developed in the current PhD project.

The new mitigation concept must be able to be integrated into both existing and future naval and aircraft sandwich structures with different configurations of sandwich face and core materials for improved robustness and damage tolerance in extreme environments. This will be demonstrated and qualified through experimental testing and numerical analysis at both ambient and low temperature environmental conditions, typical for arctic naval and high altitude aircraft operations respectively, underpinned by a new kinking criteria to be developed in close cooperation with the parallel PhD project at University of Genova.

The science underpinning the aims of the PhD project is the fracture mechanics of a bi-material interfaces and the associated testing methods and technology developed in earlier and on-going projects in the Lightweight Structures Group at the Department of Mechanical Engineering.

Responsibilities and qualifications

• Investigate, characterize experimentally and contribute to the definition of an analysis criteria for 3D crack kinking behaviour, involved in the propagation of face/core debond damages in naval and aircraft sandwich panels with high stiffness mismatch interfaces, exposed to both ambient and extreme environmental artic conditions with low temperatures, as well as combined loading, including fatigue.
• Further advance existing finite element based analysis models developed by DTU, so that they are able to predict both face/core interface propagation and kinking into the core for 3D debonds in sandwich panels, as well as expand the models for utilization in studies with combined low temperature and impact damages.
• Develop a new mitigation concept for face/core debond propagation and kinking in naval and aircraft sandwich panels caused by initial impact events, and exposed to subsequent service fatigue loads and low temperatures.
• Demonstrate on an applied scale, both the accuracy of the developed new analysis capabilities, as well as the potential of the developed mitigation concept, integrated into a typical naval and aircraft type sandwich panels and exposed to initial impact loading followed by combined service fatigue and extreme environmental loading, including low temperature exposure.

You must have a two-year master's degree (120 ECTS points) or a similar degree with an academic level equivalent to a two-year master's degree.

Approval and Enrolment
The scholarship for the PhD degree is subject to academic approval, and the candidate will be enrolled in one of the general degree programmes at DTU. For information about our enrolment requirements and the general planning of the PhD study programme, please see the DTU PhD Guide.

Assessment
Further qualifications:

• Experience/courses in experimental mechanics (mandatory).
• Experience/courses in fiber composites and sandwich structures (mandatory).
• Extensive experience/courses and interest in numerical simulations (ABAQUS or similar - mandatory).
• Knowledge of interface fracture mechanics in composites or sandwich structures will be beneficial.
• Preferable knowledge of impact mechanics.
• Scientifically curious, but also result-oriented.
• Good communication skills in English is paramount, including the ability to write scientific publications.
• Capable of working independently and in a team.
• Able to work both in front of the computer and in the laboratory.

We offer
DTU is a leading technical university globally recognized for the excellence of its research, education, innovation and scientific advice. We offer a rewarding and challenging job in an international environment. We strive for academic excellence in an environment characterized by collegial respect and academic freedom tempered by responsibility.

Salary and appointment terms
The appointment will be based on the collective agreement with the Danish Confederation of Professional Associations. The allowance will be agreed upon with the relevant union. The period of employment is 3 years.

You can read more about career paths at DTU here .

Further information
Further information may be obtained from Professor Christian Berggreen tel.: +45 4525 1373, email: [email protected] . However, pure statements of interest in the position or requests for screening of CVs prior to submission of the application will be ignored.

You can read more about Department of Mechanical Engineering at www.mek.dtu.dk . 

If you are applying from abroad, you may find useful information on working in Denmark and at DTU at DTU – Moving to Denmark.

Application procedure
Your complete online application must be submitted no later than 5 December 2021 (Danish time).

Applications must be submitted as one PDF file containing all materials to be given consideration. To apply, please open the link "Apply online", fill out the online application form, and attach all your materials in English in one PDF file. The file must include:

• A letter motivating the application (cover letter)
• Curriculum vitae
• Grade transcripts and BSc/MSc diploma
• Excel sheet with translation of grades to the Danish grading system (see guidelines and Excel spreadsheet here )

You may apply prior to obtaining your master's degree but cannot begin before having received it.

Applications received after the deadline will not be considered.

All interested candidates irrespective of age, gender, race, disability, religion or ethnic background are encouraged to apply.

DTU Mechanical Engineering covers the fundamental engineering disciplines within Solid mechanics, Fluid mechanics, Coastal and Maritime Engineering, Energy systems and energy conversion, Materials and Surface Engineering, Manufacturing Engineering, Engineering design and Product development. The department has a scientific staff of about 135 persons, 100 PhD students and a technical/administrative support staff of about 80 persons.

Technology for people
DTU develops technology for people. With our international elite research and study programmes, we are helping to create a better world and to solve the global challenges formulated in the UN’s 17 Sustainable Development Goals. Hans Christian Ørsted founded DTU in 1829 with a clear vision to develop and create value using science and engineering to benefit society. That vision lives on today. DTU has 12,900 students and 6,000 employees. We work in an international atmosphere and have an inclusive, evolving, and informal working environment. DTU has campuses in all parts of Denmark and in Greenland, and we collaborate with the best universities around the world.