The simulation of the collision process requires a description of the mechanical behaviour of the granules. Continuum mechanical models are to be used for this purpose. The material parameters of the associated constitutive models are to be determined with particle methods in this project.

Supervisor

Prof. Dr.-Ing. Alexander Düster, Dr.-Ing. Maksym Dosta, Prof. Dr.-Ing. Stefan Heinrich

Methods and work programme

To keep the simulation effort of collisions low, an approach for coupled DEM-FEM simulations is developed. For this purpose, the material used is first investigated with the help of DEM. To enable the fracture of the particles, the bonded-paricle method is used.

With the help of experimental data, both the required simulation parameters are determined and the models used are validated. The knowledge gained in this way is then used to determine the parameters for material models that can best represent particle fracture.

The results of these two steps are then used to enable DEM-FEM simulations. The coupled simulation is validated using double hull model tests that have already been carried out.

Results

For the calculation of particle fracture, a new bond model has been developed that takes into account the microcracks that occur in the material. Single and multi-particle simulations were carried out with three different bond models.

With the help of uniaxial compression tests of individual particles, the micro-behaviour of the particles can be investigated and simulated. Here, it is particularly important to take into account the shape of the particles as well as the microcracks that occur. The knowledge gained from the single particle simulations can then be used to simulate multi-particle systems.

 

With the help of DEM, it is possible to represent the mechanical properties of the material used very well in single particle simulations. Multi-particle experiments can also be represented well. Only the initial stiffness of the particle system still deviates slightly from the experimental results. In addition, the first DEM-FEM simulations have already been carried out successfully.

 

References

[1] Schöttelndreyer, M. (2015): Füllstoffe in der Konstruktion: Ein Konzept zur Verstärkung von Schiffsseitenhüllen. Dissertation, Institut für Konstruktion und Festigkeit von Schiffen, Technische Universität Hamburg-Harburg.

[2] Dosta, M. et al. (2016): Numerical and experimental analysis of influence of granule microstructure on its compression breakage. Powder Technology, 299, S. 87-97.

[3] Woitzik C. und Düster A. (2017): Modelling the material parameter distribution of expanded granules. Granular Matter, 19:52, S.1-12.

[4] Chaudry, M.A., Woitzik C., Düster A. und P. Wriggers (2018): Experimental and numerical characterization of expanded glass granules. Computational Particle Mechanics, 5, S. 297-312. 

[5] Kraus S., Woitzik C.,  Dosta M., Düster A.(2021): Simulation of granular materials with the discrete element method to investigate their suitability as crash-absorber in ship collisions. In: PAMM 21.1 (2021),e202100036. DOI: https://doi.org/10.1002/pamm.20210003

[6] Rotter S., Woitzik C., Tasdemir S., Dosta M., Düster A.(2022): Numerical investigation of the breakage and crash absorbing behavior of granular materials in ship collisions. In: Proceedings of International Conference on Processes in Natural and Technical Particle-Fluid Systems 2022 in Hamburg/Germany, Veröffentlichungen des Instituts für Geotechnik und Baubetrieb der Technischen Universität Hamburg, Heft 54, S. 37-51.

[7] Orth M., Rotter S., Safdar W., Tasdemir S., Pietsch-Braune S., Heinrich S., Düster A. (2023): Fluidized Bed Spray Coating for Improved Mechanical Properties of Particles. In: Processes 11, DOI: 10.3390/pr11020314