Multiscale Materials in Mechanics

Applied Mechanics invites to talks in guest lecture series: Multiscale Materials in Mechanics.

Visiting professor, Jörg Schröder, Institute of Mechanics, Faculty of Engineering, Universität Duisburg-Essen, will give two talks about Multiscale Materials in Mechanics.

Tuesday, May 21

12:15 - 13:00
Å 10 1121, Sonja Lyttkens

Computational Mechanics - Possibilities and Challenges (45 min open public talk at all levels).

Computational mechanics makes it possible to analyze various physical phenomena on different scales. These can range from micrometers to kilometers. The first question that arises is which numerical model to use. Here we refer to the finite element method (FEM), which offers a high degree of flexibility in the approximate solution of partial differential equations.

After an illustrative introduction to the power of numerical models, we will focus on analyzing magnetic microstructures. State-of-the-art permanent magnetic materials such as neodymium-iron-boron (NdFeB) magnets play a crucial role in the energy transition ("Energiewende") when it comes to pushing the efficiency of energy conversion devices such as wind turbines and electric motors to their limits. A significant challenge is overcoming the so-called Brown paradox's limits and increasing magnetic coercivity.

We then look at the sea ice drift in the southern polar region. This process is subject to constant change: Significant changes in the dynamics of the sea ice field can be observed both seasonally and over time scales of several decades. The extent and nature of the sea ice are important factors and critical indicators for the regional and global climate. First, we consider the modeling of freezing and thawing processes in the context of porous media theory. Then we look at sea ice drift based on the Hibler viscoplastic sea ice model using the least squares FEM.

Wednesday, May 22

10:15 - 12:00
Å 8 0101

Micromagnetic simulations for the hysteresis design of efficient magnetic materials (90 min doctoral level course with all details).

State-of-the-art permanent magnetic materials such as neodymium-iron-boron (NdFeB) magnets play a crucial role in pushing the efficiency of energy conversion devices such as wind turbines and electric motors to their limits. To support the improvement process of these materials, efficient and robust simulation techniques for magneto-mechanical characterization are needed. In this lecture, an excursus into micromagnetic theory is followed by the presentation of numerical methods for the simulation of evolving magnetic fields and magnetic hysteresis curves. The development of the magnetization vectors is determined by the Gilbert equation, which only allows rotations, but no changes in length. This constraint can be enforced in various ways with different advantages and disadvantages, which are discussed in detail.