7 research outputs found
Unsere geschützte Natur
Anliegen dieses Faltblattes ist es, bei der interessierten Öffentlichkeit Verständnis für die Ziele des Naturschutzes zu erreichen und die zum Schutz von Natur und Landschaft unverzichtbaren Schutzgebietskategorien und Kriterien vorzustellen
Towards a Dynamical Collision Model of Highly Porous Dust Aggregates
In the recent years we have performed various experiments on the collision
dynamics of highly porous dust aggregates and although we now have a
comprehensive picture of the micromechanics of those aggregates, the
macroscopic understanding is still lacking. We are therefore developing a
mechanical model to describe dust aggregate collisions with macroscopic
parameters like tensile strength, compressive strength and shear strength. For
one well defined dust sample material, the tensile and compressive strength
were measured in a static experiment and implemented in a Smoothed Particle
Hydrodynamics (SPH) code. A laboratory experiment was designed to compare the
laboratory results with the results of the SPH simulation. In this experiment,
a mm-sized glass bead is dropped into a cm-sized dust aggregate with the
previously measured strength parameters. We determine the deceleration of the
glass bead by high-speed imaging and the compression of the dust aggregate by
x-ray micro-tomography. The measured penetration depth, stopping time and
compaction under the glass bead are utilized to calibrate and test the SPH
code. We find that the statically measured compressive strength curve is only
applicable if we adjust it to the dynamic situation with a 'softness'
parameter. After determining this parameter, the SPH code is capable of
reproducing experimental results, which have not been used for the calibration
before.Comment: Accepted by "Proc. Powders and Grains 2009", Publisher AI