Project Details
Projekt
Internal dynamics of magnetic particles during fabrication and magnetomechanical loading of structured magnetic elastomers – experimental studies
Applicant
Dr. Günter K. Auernhammer
Subject Area
Fluid Mechanics
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 511114185
This project builds on results from previous works by the applicant: i) chains of magnetic particles in soft elastic matrices react to orthogonal magnetic fields by internal instabilities such as buckling; ii) groups of magnetic particles in these matrices can react to small changes in the applied magnetic field by strong structural changes in their arrangement, such as jumps into contact. We now want to investigate for structured magnetic elastomers, consisting of defined arrangements of magnetizable particles in soft elastic polymeric matrices, processes and influencing factors during fabrication on the scale of individual magnetic particles. Two aspects are of central interest. First, this concerns the fundamental understanding of structure formation during the fabrication of magnetic elastomers, i.e., the interplay between magnetically induced migration of the magnetic particles and the crosslinking kinetics of the surrounding elastomer. Can this interplay be used, for example, to generate certain desired structures and particle arrangements by time-dependent external magnetic fields during crosslinking? To answer this question, the time scales of the chemical crosslinking kinetics, the magnetically induced particle migration and the variation of orientation and strength of the applied magnetic field will be systematically varied against each other. A second focus is on the magnetomechanical properties of the resulting particle assemblies. How do the resulting particle assemblies respond to external magnetic fields that vary in orientation and strength, and how does this depend on the particle arrangement? Which particle assemblies show particularly strong changes in structure upon small changes in the applied magnetic field, i.e., are magnetomechanically highly active? In order to answer these and further questions, our experimental facilities will be enhanced. In particular, an optimized arrangement of permanent magnets (Halbach magnet) will be constructed, which allows to combine optical and mechanical observation capabilities in a way to successfully perform the planned investigations. Throughout the project, we are in close exchange with the other groups of the Research Unit, who calculate the particle dynamics on the same scale as our experiments are performed, who analyze the structure formation in comparable macroscopic samples of magnetorheological elastomers and measure their macroscopic properties, and who elucidate corresponding connections by scale-bridging simulations and link the structural properties to the macroscopic material behavior. Likewise, we are working within the Research Unit on preparing and communicating our results during public relations in a manner adapted to the specific target group.
DFG Programme
Research Units
