Postdoc in multi-scale modelling of composites vibration response @ Ghent University (Belgium)

Nowadays, there is an increasing interest to use composite materials in automotive applications, in particular the use of fibre-reinforced plastics (carbon or glass fibres in a polymer matrix) is widely considered. The use of lighter materials, and hence a reduced fuel consumption, can be one of the possible solutions for reduced CO2 emissions. As the automotive industry is mainly familiar with metals and plastics, a lot of research is being spent on the mechanical response of composites under fatigue and impact loading, and on developing new design methodologies for these "new" materials. Also, the design cycle is much shorter than in aerospace industry, so faster design and calculation methodologies are needed. Apart from these investigations, the use of composite materials in automotive applications has also other consequences. The so-called NVH (= Noise / Vibration / Harshness ) requirements have to be imposed to composite components as well, to guarantee a good acoustic comfort for the driver and passengers. However, the NVH behaviour of composites is not well understood, and due to the visco-elastic behaviour of its polymer matrix, the vibration and damping response of composite panels can be very different from the behaviour of metallic panels.

In this project, it is the purpose to investigate and validate multi-scale modelling strategies to predict the vibration and damping behaviour of composite panels. The approved research project is a collaboration between Ghent University, KULeuven, Siemens, Toyota and Nitto. The project is called "Design and analysis of the NVH behavior of lightweight panel and material systems using advanced CAE tools". Modelling strategies have to be developed to predict the complex stiffness moduli (storage modulus and loss modulus) of composites in their different orthotropic directions, based on two ingredients:

• a representative unit cell model of the fibre reinforcement architecture of the composite (e.g. unidirectional reinforcement, plain weave, twill weave,…)
• a visco-elastic frequency-dependent material model for the polymer matrix

By proper homogenization methods, the frequency-dependent stiffness and damping of the homogenized composite is predicted and can be used in early design simulations. In a second phase, the method will be validated on more complex components in a sound box, where acoustic measurements and finite element simulations will be compared. Furthermore, the unit-cell modelling of bare FRP models will be extended to unit-cell models also including the add-on layer.

The open position is a full-time postdoctoral position for 30 months, split over Ghent University (15 months) and KULeuven (15 months). We are looking for one physical person, who will do the first half of the research in Ghent and the second half of the research in Leuven (both cities are 80 km from each other, both in Flanders, Belgium). The research work will consist of:

• measurement of resonance frequencies and modal damping of different composite panels
• creation of geometrical and finite element unit-cell models for those composites
• development of suitable visco-elastic material models for the polymer matrix

• development of homogenization methods for frequency-dependent stiffness and damping
• measurement of the acoustic response of more complex composite components also including an add-on layer in a sound box
• validation of the acoustic measurements with finite element simulations.

The "Mechanics of Materials and Structures" research group at Ghent University (Prof. Wim VAN PAEPEGEM) has 30-years experience with mechanics of composites, and recently developed also test set-ups and finite element simulations for modal vibration and damping of composite panels. 
The "Noise and Vibration Engineering" research group of the KU Leuven Department of Mechanical Engineering (Prof. Wim Desmet) has a long-term experience in experimental and numerical techniques for structural dynamic and vibro-acoustic analysis of materials and systems, with focus on automotive, aerospace and industrial machinery applications (https://www.mech.kuleuven.be/en/pma/research/mod). These activities have led a.o. to the foundation of spin-off company LMS International, now Siemens PLM Software, with whom a close collaboration will be set-up in the present project, leading to new simulation methodologies for the NVH behaviour of composite panels.

Only candidates with a PhD degree should apply. The candidate should combine a background in computational mechanics of composites (preferably multi-scale modelling) with knowledge in the field of vibrations/acoustics or visco-elastic and frequency-dependent behaviour of polymers.