This study is devoted to the magneto-mechanical characterization of heterogeneous magnetoactive elastomers based on an elastic polydimethylsiloxane matrix with embedded spherical magnetic soft microparticles and magnetic hard microparticles of irregular shape. An issue of the anisotropic mechanical properties of these smart composites is considered. Non-magnetized and pre-magnetized specimens are characterized using a planar shear and axial loading in an externally applied homogeneous magnetic field. The field direction differs relative to the direction of the field used for the specimens pre-magnetization. Results of the different methods allow comparison of the tensile shear moduli for the samples with an initially identical composition. Obtained results demonstrate a strong correlation between the composite behaviour and orientation of the magnetic field used for the pre-magnetization of the sample relative to the external field applied to a sample during the test. Composites pre-magnetized in the direction parallel to an applied mechanical force and external magnetic field show higher magnetorheological response than composites pre-magnetized transversally to the force and the field. Application of the external field directed opposite to the direction of the pre-magnetization reduces the observed stiffening. Moreover, in this situation a softening of the material can be observed, depending on the magnitude of the external field and the field used for pre-magnetization. This article is part of the theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’.

The utilization of ‘smart’ materials with adaptable properties or characteristics are a widespread research issue, offering potential for tailored solutions, weight reduction or added value of products through integrated functionality. Therefore, field controlled hybrid materials such as magnetorheological (MR) elastomers or electrorheological (ER) fluids are particularly valuable and within the focus of science and research. At the same time, additive manufacturing has had a strong influence on production processes over the past decade. Today a 3D printer can be found across all disciplines in almost every company, research institution and even in many private households. The Fused Filament Fabrication (FFF) process is especially popular due to its low cost and simplicity. Within this work, a new approach for the generation of field-structured magnetic elastomers using the FFF process and a correspondingly developed prototype print head for implementation are presented and discussed. With its unique research landscape Dresden offers excellent conditions for the development of innovative processes and composite materials in the field of generative manufacture. In the ‘Dresden Concept’ network, experts from various disciplines collaborate and investigate the entire spectrum starting from biological materials, through lightweight fibre reinforced polymer composites, to high-temperature ceramics. This article is part of the theme issue ‘Patterns in soft and biological matters’.

Adaptability of properties of magnetic materials such as magnetorheological (MR) fluids, MR elastomers (MRE), and other magneto-active (MA) materials drives scientific activities worldwide, trying to broaden the fields of application of such materials. In our work, we focused on the utilization and implementation of existing material models to realize a praxis-oriented coupled anisotropic material model for the commercial finite element (FE) software ABAQUS taking into account magneto-mechanical interactions. By introducing this material model, a first step is done to predict and optimize the behavior of MA materials.

Ferrofluids receive growing importance in the biomedical area, leading to the requirement of a detailed understanding of the flow behavior of the fluids, especially under the influence of external magnetic fields as used in those applications. It has been shown that biocompatible ferrofluids used in this regard show a strong magnetoviscous effect-a rise of viscosity, if an external magnetic field is applied-for low shear rates and comparatively weak magnetic fields. Nevertheless, in most of the potential applications in the biomedical context, the ferrofluids will be exposed to high shear rates and strong magnetic fields. Therefore, it is of special interest to characterize the fluids under such conditions and to measure the viscosity for several magnetic field strengths and for high shear rates to enable exact predictions of the flow behavior and therefore enabling an effective and safe application.