Contact and Breakage Mechanics of Particles

During transportation, storage and handling the particles are mechanically stressed due to particle-particle and particle-wall contacts which can lead to the unwanted breakage or attrition phenomena. The focus of our research in this area is the physical based study of the contact deformation and breakage behavior of the particles and agglomerates under various mechanical loading conditions: compression, tension, shearing, bending, impact et al.

Using different experimental setups, e.g. compression tester, impact gun, free fall apparatus, shear and attrition tester, high speed analysis, we obtain the basic mechanical properties of single particles and powders: modulus of elasticity, stiffness, yield point, hardness, strength, cohesion, friction, restitution coefficient, flowability et al. Based on the experimental data we develop contact models to describe the mechanical interaction of solids particles sized from few micrometers to the millimeter range. Moreover, the breakage criteria of the particles and agglomerates will be described depending on the microstructure (porosity, packing structure and adhesion mechanisms of primary particles) and material parameters (elastic, elastic-plastic or plastic behavior, viscoelasticity and glass transition temperature).

We aim to provide fundamental knowledge on the mechanical behavior of the granular materials under wet conditions in order to predict the dynamics of different industrial multiphase processes, e.g. for coating, granulation and agglomeration.

The developed models are used in the Discrete Element Simulations of the particulate systems to predict the breakage probability and breakage function, particle dynamics as well as agglomeration probability in different industrial processes, like agglomeration, mixing, pheumatic transportation and milling.

The institute participates in the DFG Priority Program SPP 1486 “Particles in Contact” and Collaborative Research Centre “Maßgeschneiderte Multiskalige Materialssysteme” (production, modeling and characterization of ceramic composite materials).