Aarhus Universitets segl

Projects

On-going, Past Projects and Proposals for R&D and MSc students:


VILLUM Experiment: Rupture and adherence of architected materials

The intribuing role of material architecture and how it can be juggled to enhance mechanical properties.

This projected started on 01.04.2023 and will run until 30.03.2025. If you are interested in participating please feel free to reach me.

Post-doctoral researcher: Ping Hu (pihu@mpe.au.dk)

Contact: mibu@mpe.au.dk

Funding: The Veloux Foundations thorugh VILLUM Experiment program

Industrial Post-doctoral and Possible R&D and Master Projects on Project on Durability of Composite Materials in Harsh Environment

The project aims in exploring use of composite materials as components of marine engine cooler system. Here, the mechanical dynamical loading act together with high temperature in a rather humid, salty and exhaust gas conditions. Can composite materials be used? Help in finding it out chosing the material and proposing design leading to much lighter and better adopted structure.

Industrial Post-doc: Simon Heide (shj@eng.au.dk)

Contact: mibu@mpe.au.dk

Industrial Partner: Vestas Aircoil

You can also contact: Claus Ibsen ci@vestas-aircoil.com

R&D and Master Project on Unstable Crack Growth: Geometrical and Material Effects

We investigate effect of local surface heterogeneities on macroscale parameters, stiffness and fracture energy, of adhesive joints. Through scaling argument one can recognize that for some geometries and materials size of heterogeneity can dominate structural response. Once this is the case any of the nowadays used numerical crack growth models will lose validity. While this being the case, it does not need to mean that heterogeneities are unwanted. This project aims in proposing a general framework for modelling crack growth along interfaces with locally spatial-dependent fracture toughness.

Related project: EU COST CA18120: Reliable roadmap for certification of bonded primary structures

Student:  Adrianos Athanasiadis Fotopoulos

Collaboration: TU Delft

There are still plenty of ideas waiting for exploration and you -> Contact: mibu@eng.au.dk

R&D and Master Project on Adhesion of Hierarchical Interfaces

The adhesion of solids is often associated to at least one of the chemical/physical interactions between them, e.g. van der Waals forces, interdiffusion, electrostatic forces or similar leading. However, throughout biology (like a gecko feet) geometry of the structure, rather than the surface energy, is used to control strength and to control adhesion. Such path of interface materials design is yet to be fully exploited for the industrial applications however some already existing data are looking very promising.

Introduction of geometrical features along the interface breaks the usual failure mechanisms paradigm introducing new one, most of the time much more complex. This in return may lead, if correctly designed, to a significantly improved ‘apparent’ adhesion, while leaving the ‘intrinsic’ adhesion untouched. With this idea in mind, and with initial results highlining efficiency of the approach, the present project should lead to a fully quantified process of adhesion enhancement via control of interface geometry. The work is planned to unfold via the R&D/Specialization and be followed by the master thesis.

During the R&D project you will learn how to set-up the experiments and prepare the specimens, incl. molding and 3D printing. You will also develop a set-up for conducting multiangle peel experiments. This set-up together with the theoretical knowledge gained will serve as the basis for the future master thesis.

During the master thesis you will investigate the so-called 0th and 1st generation hierarchy cases. It is expected that the combination of geometrical parameters such as characteristic dimension of the interface wave - amplitude and band width along with the distance between the bands will be enough to control level of adhesion. Theoretical model should be developed for full appraisal of the problem.

For further information please contact:

Marcelo Dias (madias@eng.au.dk) or Michal Budzik (mibu@eng.au.dk).


References:

Kendall, K. (1975). Control of cracks by interfaces in composites. Proc. R. Soc. Lond. A341(1627), 409-428.  

Xia, S., Ponson, L., Ravichandran, G., & Bhattacharya, K. (2012). Toughening and asymmetry in peeling of heterogeneous adhesives. Physical review letters108(19), 196101.  

Heide-Jørgensen, S., & Budzik, M. K. (2018). Effects of bondline discontinuity during growth of interface cracks including stability and kinetic considerations. Journal of the Mechanics and Physics of Solids117, 1-21. 

Gao, H., Wang, X., Yao, H., Gorb, S., & Arzt, E. (2005). Mechanics of hierarchical adhesion structures of geckos. Mechanics of Materials37(2-3), 275-285.  

Rayneau-Kirkhope, D., Mao, Y., Farr, R., & Segal, J. (2012). Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing. Mechanics Research Communications46, 41-46.  

R&D and Master Projects on Understanding the Process of Materials Wear

Wear of solid surfaces causes a huge amount of material and energy losses with serious environmental, economic, and industrial impacts. Despite its vital importance, the scientific understanding of wear process is surprisingly limited and therefore wear prediction fully relies on empirical data and cannot be obtained from any physical model. The main reason for this limited understanding is that, direct observation and modeling of material loss from surfaces present notorious challenges.

The process of surface material degradation (due to plasticity, fatigue and fracture) emerges from complex chemical and physical processes. In this project, we aim to investigate and understand the process of material removal using a model experimental setup and complementary finite element simulations. Converting a tensile test to a pure shear test, the project investigates failure mechanisms of a junction under shear loading.

During this project, the student learns new knowledge about different mechanisms and models of material wear. The student also learns several experimental techniques, including laser cutting, tensile and shear mechanical tests and data analysis.

For further information, please contact Ramin Aghababaei (aghababaei@eng.au.dk) or Michal Budzik (mibu@eng.au.dk).


References:

Aghababaei, R., Warner, D. H., & Molinari, J. F. (2016). Critical length scale controls adhesive wear mechanisms. Nature communications7, 11816.  

Aghababaei, R., Warner, D. H., & Molinari, J. F. (2017). On the debris-level origins of adhesive wear. Proceedings of the National Academy of Sciences114(30), 7935-7940.  

Budzik, M. K., Jumel, J., Salem, N. B., & Shanahan, M. E. R. (2013). Instrumented end notched flexure–Crack propagation and process zone monitoring Part II: Data reduction and experimental. International Journal of Solids and Structures50(2), 310-319.  

The European Union COST project on bonded primary structures

Reliable roadmap for certification of bonded primary structures


Project no.: CA18120

Project funding: EU COST actions

COST actions  

Period of project implementation: 2019-04-04 - 2023-04-03

Project partners: 28 countries and more than 80 participants including academia, leading European industry and policy makers from Austria, France, Netherlands, Portugal, Romania, Sweden, United Kingdom, Croatia, Cyprus, Denmark, Greece, Poland, Slovakia, Slovenia, Switzerland

Areas of Expertise Relevant for the Action:

● Mechanical engineering: Mechanical and manufacturing engineering (shaping, mounting, joining, separation)

● Mechanical engineering: Aerospace engineering

● Civil engineering: Civil engineering

● Materials engineering: Structural properties of materials

Keywords:

● Adhesive bonding

● Critical load bearing structures

● Certification


Role in the project: Our group is co-author and member of Work Package 2 - Design Phase

This WG will coordinate research related to the design of adhesively bonded composite structures taking into account geometrical configurations, new design features, fatigue and impact loading, creep phenomena, damage tolerance, imperfect bonding and environmental effects. Although considerable amount of work has been already performed by researchers who developed several design algorithms, there is no generally accepted model yet. The objective of the WG is to propose a universal progressive damage algorithm that incorporates the aforementioned parameters and complies with the engineering allowables and design rules. In order to meet this objective, the WG will perform the following tasks:

• Task 2.1. Explore new design concepts (geometrical configurations and new crack arresting design features).

• Task 2.2. Compare testing procedures for bondline characterization and models validation (under static, fatigue and impact loading, creep phenomena, imperfect bonding and environmental effects).

• Task 2.3. Evaluate different design methodologies for the structural behaviour and progressive damage analysis of adhesively bonded structures.

If you are the future master student interested in composites, bonding and the project and would like to actively participate in it, contact Michal.


The European Union COST project on behaviour of composites under high strain loading HiStrate