@article{HesmerTatartschukZhuromskyyetal., author = {Hesmer, Frank and Tatartschuk, Eugen and Zhuromskyy, Oleksandr and Radkovskaya, Anna A. and Shamonin (Chamonine), Mikhail and Hao, Tong and Stevens, Chris J. and Faulkner, Grahame and Edwards, David J. and Shamonina, Ekaterina}, title = {Coupling mechanisms for split ring resonators: Theory and experiment}, series = {Physica status solidi b}, volume = {244}, journal = {Physica status solidi b}, number = {4}, publisher = {Wiley}, doi = {10.1002/pssb.200674501}, pages = {1170 -- 1175}, abstract = {We study experimentally and theoretically coupling mechanisms between metamaterial elements of the split ring resonator (SRR) type. We show that, depending on the orientation of the elements relative to each other, the coupling may be either of magnetic or electric type or a combination of both. Experimental results on SRRs with resonances around 1.7-1.9 GHz agree quantitatively with results of simulations (CST Microwave Studio). Further simulations provide analysis for a variety of SRRs both in the GHz and in the 20 THz frequency regions. The variety of coupling mechanisms can be employed in designing near field manipulating devices based on propagation of slow waves.}, language = {en} } @article{KlankHagedornHolthausetal., author = {Klank, Michael and Hagedorn, Oliver and Holthaus, Carsten and Shamonin (Chamonine), Mikhail and D{\"o}tsch, Horst}, title = {Characterization and optimization of magnetic garnet films for magneto-optical visualization of magnetic field distributions}, series = {NDT \& E International}, volume = {36}, journal = {NDT \& E International}, number = {6}, publisher = {Elsevier}, doi = {10.1016/S0963-8695(03)00012-4}, pages = {375 -- 381}, abstract = {Rare-earth iron garnet films with in-plane anisotropy grown on (111)-oriented substrates can be used as magneto-optical indicator films for visualization of magnetic leakage fields in nondestructive evaluation. The influence of Faraday rotation, Faraday ellipticity, absorption and film thickness on the performance of a magneto-optical indicator film is investigated. A new optimization method is introduced and compared with the method of contrast optimization. The theory is experimentally verified and an application example is presented.}, language = {en} } @article{LukyanetsSnarskiiShamoninChamonineetal., author = {Lukyanets, S. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Bakaev, V. V.}, title = {Calculation of magnetic leakage field from a surface defect in a linear ferromagnetic material: an analytical approach}, series = {NDT \& E International}, volume = {36}, journal = {NDT \& E International}, number = {1}, publisher = {Elsevier}, doi = {10.1016/s0963-8695(02)00071-3}, pages = {51 -- 55}, abstract = {A novel analytical approach for calculating the magnetic leakage field from surface defects is proposed and demonstrated for the case of a linear ferromagnetic material. The novelty of the theory is that it relates the distribution of induced magnetic charges to the surface shape. An excellent agreement between the analytical and numerical results is shown. The functional relations between different magnetic field components are discussed.}, language = {en} } @article{BakaevSnarskiiShamoninChamonine, author = {Bakaev, V. V. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail}, title = {The permeability and remanent magnetization of a randomly inhomogeneous two-phase medium}, series = {Technical Physics}, volume = {47}, journal = {Technical Physics}, number = {1}, publisher = {Springer}, doi = {10.1134/1.1435901}, pages = {125 -- 128}, abstract = {A randomly inhomogeneous composite consisting of two, ferromagnetic and nonmagnetic (para-or diamagnetic), phases is considered. The dependence of the effective permeability of the composite on the concentration of the ferromagnetic phase and on the applied magnetic field is found for the case of the negligible hysteresis loop. When the hysteresis loop is appreciable, the remanent magnetization as a function of the ferromagnet concentration is calculated.}, language = {en} } @article{BakaevSnarskiiShamoninChamonine, author = {Bakaev, V. V. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail}, title = {The effective magnetic permeability of a two-phase fibred ferromagnetic composite}, series = {Technical Physics}, volume = {46}, journal = {Technical Physics}, number = {12}, publisher = {Springer}, doi = {10.1134/1.1427995}, pages = {1571 -- 1574}, language = {en} } @article{KovalevBelyaevavonHofenetal., author = {Kovalev, Alexander and Belyaeva, Inna A. and von Hofen, Christian and Gorb, Stanislav and Shamonin (Chamonine), Mikhail}, title = {Magnetically Switchable Adhesion and Friction of Soft Magnetoactive Elastomers}, series = {Advanced Engineering Materials}, volume = {24}, journal = {Advanced Engineering Materials}, number = {10}, publisher = {WILEY-VCH}, doi = {10.1002/adem.202200372}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-45283}, pages = {1 -- 8}, abstract = {Herein, the effect of an applied moderate (~240 mT) magnetic field on the work of adhesion (WoA) of mechanically soft (the shear modulus ~10 kPa) magnetoactive elastomer (MAE) samples with two different mass fractions (70 and 80 wt\%) of carbonyl iron powder (CIP) is concerned. The unfilled elastomer sample is used for comparison. Due to some sedimentation of filling particles, the concentration of inclusions in thin (~10 μm) subsurface layers is different. It is shown that the WoA increases (up to 1.8-fold) on the particle-enriched side (PES) in the magnetic field and its value is higher for higher filler concentration. On the particle-depleted side (PDS), WoA does not depend on particle concentration and on the magnetic field. Adhesion and friction are coupled in MAEs. No statistically significant difference in the friction coefficient, determined from the extended Amontons´ law, depending on sample side, CIP concentration, or presence of magnetic field is found. However, the PDS in the magnetic field demonstrates significantly higher critical shear stress compared to that for the PES or PDS in the absence of magnetic field. Correlations between different surface properties are discussed. Obtained results are useful for the development of magnetically controllable soft robots.}, language = {en} } @article{LohmeyerShamoninChamonineHertel, author = {Lohmeyer, Manfred and Shamonin (Chamonine), Mikhail and Hertel, Peter}, title = {Integrated optical circulator based on radiatively coupled magneto-optic waveguides}, series = {Optical Engineering}, volume = {36}, journal = {Optical Engineering}, number = {3}, publisher = {SPIE}, doi = {10.1117/1.601255}, pages = {889 -- 895}, abstract = {In a three-guide coupler with multimode central waveguide, more than two modes of the entire structure participate in the coupling between the outer waveguides. Using a three-mode approximation we found simple conditions for complete power transfer between the outer waveguides: the device length has to match certain multiples of the con- ventionally defined coupling length. The specific form of the relevant modes allows us to design a magneto-optic isolator or circulator with significantly reduced device length (as compared to the conventional nonreciprocal coupler). The performance of the proposed devices is simulated by propagating-mode calculations. Estimates for admissible fabrication tolerances for the layer thicknesses are presented.}, language = {en} } @article{BelyaevaKramarenkoStepanovetal., author = {Belyaeva, Inna A. and Kramarenko, Elena Yu and Stepanov, Gennady V. and Sorokin, Vladislav V. and Stadler, Dominik and Shamonin (Chamonine), Mikhail}, title = {Transient magnetorheological response of magnetoactive elastomers to step and pyramid excitations}, series = {SOFT MATTER}, volume = {12}, journal = {SOFT MATTER}, number = {11}, publisher = {ROYAL SOC CHEMISTRY}, doi = {10.1039/c5sm02690c}, pages = {2901 -- 2913}, abstract = {Transient rheological response of magnetoactive elastomers is experimentally studied using dynamic torsion at a fixed oscillation frequency in temporally stepwise changing magnetic fields and oscillation amplitudes. For step magnetic-field excitations, at least three exponential functions are required to reasonably describe the time behavior of the storage shear modulus over long time scales (>10(3) s). The deduced characteristic time constants of the corresponding rearrangement processes of the filler network differ approximately by one order of magnitude: tau(1) less than or similar to 10(1) s, tau(2) similar to 10(2) s, and tau(3) similar to 10(3) s. The sudden imposition of the external magnetic field activates a very fast rearrangement process with the characteristic time under 10 s, which cannot be determined more precisely due to the measurement conditions. Even more peculiar transient behavior has been observed during pyramid excitations, when either the external magnetic field was first stepwise increased and then decreased in a staircase manner at a fixed strain amplitude gamma or the strain amplitude gamma was first stepwise increased and then decreased in a staircase manner at a fixed magnetic field. In particular, the so-called "cross-over effect'' has been identified in both dynamical loading programs. This cross-over effect seems to be promoted by the application of the external magnetic field. The experimental results are discussed in the context of the specific rearrangement of the magnetic filler network under the simultaneous action of the external magnetic field and shear deformation. Striking similarities of the observed phenomena to the structural relaxation processes in glassy materials and to the jamming transition of granular materials are pointed out. The obtained results are important for fundamental understanding of material behavior in magnetic fields as well as for the development of devices on the basis of magnetoactive elastomeric materials.}, language = {en} } @article{BelyaevaKramarenkoShamoninChamonine, author = {Belyaeva, Inna A. and Kramarenko, Elena Yu and Shamonin (Chamonine), Mikhail}, title = {Magnetodielectric effect in magnetoactive elastomers: Transient response and hysteresis}, series = {POLYMER}, volume = {127}, journal = {POLYMER}, publisher = {ELSEVIER}, doi = {10.1016/j.polymer.2017.08.056}, pages = {119 -- 128}, abstract = {Magnetodielectric properties of magnetoactive elastomers comprising micrometer-sized iron particles dispersed in compliant elastomer matrices are experimentally studied in stepwise time-varying dc magnetic fields. It is found that imposition of magnetic field significantly increases both the effective lossless permittivity of these composite materials as well as their effective conductivity. These magnetodielectric effects are more pronounced for larger concentrations of soft-magnetic filler particles and softer elastomer matrices. The largest observed relative change of the effective dielectric constant in the maximum magnetic field of 0.57 T is of the order of 1000\%. The largest observed absolute change of the loss tangent is approximately 0.8. The transient response of the magnetodielectric effect to a step magnetic-field excitation can be rather complex. It changes from a simple monotonic growth with time for small magnetic-field steps (<0.1 T) to a non-monotonic behavior with a significant rapidly appearing overshoot for large magnetic-field steps (>0.3 T). The settling time to the magnetic-field step excitation can reach roughly 1000 s and it depends on the applied magnetic field and sample composition. There is also significant hysteresis of the magnetodielectric effect on the externally applied magnetic field. These findings are attributed to the rearrangement of ferromagnetic filler particles in external magnetic fields. The results will be useful for understanding and predicting the transient behavior of magnetoactive elastomers in applications where the control magnetic field is time dependent. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{SorokinBelyaevaShamoninChamonineetal., author = {Sorokin, Vladislav V. and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail and Kramarenko, Elena Yu}, title = {Magnetorheological response of highly filled magnetoactive elastomers from perspective of mechanical energy density: Fractal aggregates above the nanometer scale?}, series = {Physical Review E}, volume = {95}, journal = {Physical Review E}, number = {6}, publisher = {Amer Physical Soc}, doi = {10.1103/PhysRevE.95.062501}, abstract = {The dynamic shear modulus of magnetoactive elastomers containing 70 and 80 mass \% of carbonyl iron microparticles is measured as a function of strain amplitude via dynamic torsion oscillations in various magnetic fields. The results are presented in terms of the mechanical energy density and considered in the framework of the conventional Kraus model. The form exponent of the Kraus model is further related to a physical model of Huber et al. [Huber et al., J. Phys.: Condens. Matter 8, 409 (1996)] that uses a realistic representation for the cluster network possessing fractal structure. Two mechanical loading regimes are identified. At small strain amplitudes the exponent beta of the Kraus model changes in an externally applied magnetic field due to rearrangement of ferromagnetic-filler particles, while at large strain amplitudes, the exponent beta seems to be independent of the magnetic field. The critical mechanical energy characterizing the transition between these two regimes grows with the increasing magnetic field. Similarities between agglomeration and deagglomeration of magnetic filler under simultaneously applied magnetic field and mechanical shear and the concept of jamming transition are discussed. It is proposed that the magnetic field should be considered as an additional parameter to the jamming phase diagram of rubbers filled with magnetic particles.}, language = {en} } @article{BelyaevaKleppLemmeletal., author = {Belyaeva, Inna A. and Klepp, J{\"u}rgen and Lemmel, Hartmut and Shamonin (Chamonine), Mikhail}, title = {Feasibility of Probing the Filler Restructuring in Magnetoactive Elastomers by Ultra-Small-Angle Neutron Scattering}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {10}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app11104470}, pages = {1 -- 9}, abstract = {Ultra-small-angle neutron scattering (USANS) experiments are reported on isotropic magnetoactive elastomer (MAE) samples with different concentrations of micrometer-sized iron particles in the presence of an in-plane magnetic field up to 350 mT. The effect of the magnetic field on the scattering curves is observed in the scattering vector range between 2.5 x 10(-5) and 1.85 x 10(-4) angstrom(-1). It is found that the neutron scattering depends on the magnetization history (hysteresis). The relation of the observed changes to the magnetic-field-induced restructuring of the filler particles is discussed. The perspectives of employing USANS for investigations of the internal microstructure and its changes in magnetic field are considered.}, language = {en} } @article{GlavanBelyaevaShamoninChamonine, author = {Glavan, Gašper and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail}, title = {On the Piezomagnetism of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields: Height Modulation in the Vicinity of an Operating Point by Time-Harmonic Fields}, series = {Polymers}, volume = {16}, journal = {Polymers}, number = {19}, doi = {10.3390/polym16192706}, abstract = {Soft magnetoactive elastomers (MAEs) are currently considered to be promising materials for actuators in soft robotics. Magnetically controlled actuators often operate in the vicinity of a bias point. Their dynamic properties can be characterized by the piezomagnetic strain coefficient, which is a ratio of the time-harmonic strain amplitude to the corresponding magnetic field strength. Herein, the dynamic strain response of a family of MAE cylinders to the time-harmonic (frequency of 0.1-2.5 Hz) magnetic fields of varying amplitude (12.5 kA/m-62.5 kA/m), superimposed on different bias magnetic fields (25-127 kA/m), is systematically investigated for the first time. Strain measurements are based on optical imaging with sub-pixel resolution. It is found that the dynamic strain response of MAEs is considerably different from that in conventional magnetostrictive polymer composites (MPCs), and it cannot be described by the effective piezomagnetic constant from the quasi-static measurements. The obtained maximum values of the piezomagnetic strain coefficient (∼102 nm/A) are one to two orders of magnitude higher than in conventional MPCs, but there is a significant phase lag (35-60°) in the magnetostrictive response with respect to an alternating magnetic field. The experimental dependencies of the characteristics of the alternating strain on the amplitude of the alternating field, bias field, oscillation frequency, and aspect ratio of cylinders are given for several representative examples. It is hypothesized that the main cause of observed peculiarities is the non-linear viscoelasticity of these composite materials.}, language = {en} } @article{JezeršekKrieglKravanjaetal., author = {Jezeršek, Matija and Kriegl, Raphael and Kravanja, Gaia and Hribar, Luka and Drevenšek-Olenik, Irena and Unold, Heiko and Shamonin (Chamonine), Mikhail}, title = {Control of Droplet Impact through Magnetic Actuation of Surface Microstructures}, series = {Advanced Materials Interfaces}, volume = {10}, journal = {Advanced Materials Interfaces}, number = {11}, publisher = {Wiley}, doi = {10.1002/admi.202202471}, abstract = {An effective method for on-demand control over the impact dynamics of droplets on a magnetoresponsive surface is reported. The surface is comprised of micrometer-sized lamellas from a magnetoactive elastomer on a copper substrate. The surface itself is fabricated using laser micromachining. The orientation of the lamellae is switched from edge-on (orthogonal to the surface) to face-on (parallel to the surface) by changing the direction of a moderate (<250 mT) magnetic field. This simple actuation technique can significantly change the critical velocities of droplet rebound, deposition, and splashing. Rebound and deposition regimes can be switched up to Weber number We < 13 ± 3, while deposition and splashing can be switched in the range of 32 < We < 52. Because a permanent magnet is used, no permanent power supply is required for maintaining the particular regime of droplet impact. The presented technology is highly flexible and enables selective fabrication and actuation of microstructures on complex devices. It has great potential for applications in soft robotics, microfluidics, and advanced thermal management.}, language = {en} } @article{GlavanKettlBrunhuberetal., author = {Glavan, Gašper and Kettl, Wolfgang and Brunhuber, Alexander and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena}, title = {Effect of Material Composition on Tunable Surface Roughness of Magnetoactive Elastomers}, series = {Polymers}, volume = {11}, journal = {Polymers}, number = {4}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/polym11040594}, pages = {1 -- 13}, abstract = {We investigated magnetic-field-induced modifications of the surface roughness of magnetoactive elastomers (MAEs) with four material compositions incorporating two concentrations of ferromagnetic microparticles (70 wt\% and 80 wt\%) and exhibiting two shear storage moduli of the resulting composite material (about 10 kPa and 30 kPa). The analysis was primarily based on spread optical reflection measurements. The surfaces of all four materials were found to be very smooth in the absence of magnetic field (RMS roughness below 50 nm). A maximal field-induced roughness modification (approximately 1 m/T) was observed for the softer material with the lower filler concentration, and a minimal modification (less than 50 nm/T) was observed for the harder material with the higher filler concentration. All four materials showed a significant decrease in the total optical reflectivity with an increasing magnetic field as well. This effect is attributed to the existence of a distinct surface layer that is depleted of microparticles in the absence of a magnetic field but becomes filled with particles in the presence of the field. We analyzed the temporal response of the reflective properties to the switching on and off of the magnetic field and found switching-on response times of around 0.1 s and switching-off response times in the range of 0.3-0.6 s. These observations provide new insight into the magnetic-field-induced surface restructuring of MAEs and may be useful for the development of magnetically reconfigurable elastomeric optical surfaces.}, language = {en} } @article{GlavanSalamonBelyaevaetal., author = {Glavan, Gašper and Salamon, Peter and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena}, title = {Tunable surface roughness and wettability of a soft magnetoactive elastomer}, series = {Journal of applied polymer science}, volume = {135}, journal = {Journal of applied polymer science}, number = {18}, publisher = {Wiley}, doi = {10.1002/app.46221}, abstract = {Surface topographical modifications of a soft magnetoactive elastomer (MAE) in response to variable applied magnetic field are investigated. The analysis is performed in situ and is based on optical microscopy, spread optical reflection and optical profilometry measurements. Optical profilometry analysis shows that the responsivity of magnetic field-induced surface roughness with respect to external magnetic field is in the range of 1 mu m/T. A significant hysteresis of surface modifications takes place for increasing and decreasing fields. Investigations of shape of sessile water droplets deposited on the MAE surface reveal that field-induced topographical modifications affect the contact angle of water at the surface. This effect is reversible and the responsivity to magnetic field is in the range of 20 degrees/T. Despite the increased surface roughness, the apparent contact angle decreases with increasing field, which is attributed to the field-induced protrusion of hydrophilic microparticles from the surface layer.}, language = {en} } @article{KravanjaKrieglHribaretal., author = {Kravanja, Gaia and Kriegl, Raphael and Hribar, Luka and Glavan, Gašper and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail and Jezeršek, Matija}, title = {Magnetically Actuated Surface Microstructures for Efficient Transport and Tunable Separation of Droplets and Solids}, series = {Advanced Engineering Materials}, volume = {25}, journal = {Advanced Engineering Materials}, number = {22}, publisher = {Wiley-VCH}, issn = {1527-2648}, doi = {10.1002/adem.202301000}, pages = {1 -- 11}, abstract = {Efficient transportation of droplets (∽10 ¹ ̶̶̶̶ 10 ² µl) and small solid objects (∽10 ¹ ̶ 10 ² mm ³ ) have important applications in many fields, such as microfluidics, lab-on-a-chip devices, drug delivery, etc. A novel multifunctional surface consisting of a periodic array of micro-lamellae from a soft magnetoactive elastomer (MAE) on a plastic substrate is reported for these purposes. The physical origin of the propulsion is the bending of soft magnetic lamellae in non-uniform magnetic fields, which is also observed in uniform magnetic fields. The magnetoactive surface is fabricated using a facile and rapid method of laser ablation. The propulsion of items is realized using a four-pole rotating magnet. This results in a cyclic lamellar fringe motion over the micro-structured surface and brings an advantage of easy reciprocation of transport by rotation reversal. Two modes of object transportation are identified: "pushing" mode for precise control of droplet and solid positioning and "bouncing" mode for heavier solid objects transportation. A water droplet of 5 μl or a glass sphere with a 2.1 mm diameter can be moved at a maximum speed of 60 mm s ⁻¹ . The multifunctionality of the proposed mechatronic platform is demonstrated on the examples of selective solid-liquid separation and droplet merging.}, language = {en} } @article{KravanjaBelyaevaHribaretal., author = {Kravanja, Gaia and Belyaeva, Inna A. and Hribar, Luka and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail and Jezeršek, Matija}, title = {Laser Micromachining of Magnetoactive Elastomers as Enabling Technology for Magnetoresponsive Surfaces}, series = {Advanced Materials Technologies}, volume = {7}, journal = {Advanced Materials Technologies}, number = {5}, publisher = {Wiley}, doi = {10.1002/admt.202101045}, pages = {1 -- 8}, abstract = {A simple method for structuring of the surface of a magnetoactive elastomer (MAE) on the tens of micrometers scale, which capabilities extend beyond conventional mold-based polymer casting, is reported. The method relies on the ablation of the material by absorption of nanosecond infrared pulses from a commercial laser. It is shown that it is possible to fabricate parallel lamellar structures with a high aspect ratio (up to 6:1) as well as structures with complex scanning trajectories. The method is fast (fabrication time for the 7 × 7 mm2 is about 60 s), and the results are highly reproducible. To illustrate the capabilities of the fabrication method, both orthogonal to the MAE surface and tilted lamellar structures are fabricated. These magnetosensitive lamellae can be easily bent by ±45° using an external magnetic field of about 230 mT. It is demonstrated that this bending allows one to control the sliding angle of water droplets in a great range between a sticky (>90°) and a sliding state (<20°). Perspectives on employing this fabrication technology for magnetosensitive smart surfaces in microfluidic devices and soft robotics are discussed.}, language = {en} } @article{KravanjaBelyaevaHribaretal., author = {Kravanja, Gaia and Belyaeva, Inna A. and Hribar, Luka and Drevenšek-Olenik, Irena and Jezeršek, Matija and Shamonin (Chamonine), Mikhail}, title = {Tunable Drop Splashing on Magnetoactive Elastomers}, series = {Advanced Materials Interfaces}, volume = {8}, journal = {Advanced Materials Interfaces}, number = {11}, publisher = {Wiley}, doi = {10.1002/admi.202100235}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-24504}, pages = {1 -- 7}, abstract = {The significant effect of an external dc magnetic field on the splashing behavior of ethanol drops impacting on the unstructured (flat) surface of soft magnetoactive elastomers (MAEs) is reported. The Weber number corresponding to the transition between the deposition and the splashing regime is reduced by ≈20\% in a moderate magnetic field of ≈300 mT. Alongside this effect, a two-fold increase of the initial deceleration of the ejection sheet is observed for the softest sample. The main underlying mechanism for the observed phenomena is believed to be the magnetic-field-induced stiffening of the MAEs. Further possible mechanisms are magnetically induced changes in the surface roughness and magnetic-field-induced plasticity (magnetic shape memory effect). The potential application areas are magnetically regulable wetting and magneto-responsive surfaces for controlling the drop splashing.}, language = {en} } @inproceedings{KravanjaBelyaevaHribaretal., author = {Kravanja, Gaia and Belyaeva, Inna A. and Hribar, Luka and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail and Jezeršek, Matija}, title = {Adaptive Magneto-Responsive Surfaces Fabricated by Laser-Based Microstructuring}, series = {Proceedings of the ASME 2022 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS 2022): September 12-14, 2022, Dearborn, Michigan}, booktitle = {Proceedings of the ASME 2022 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS 2022): September 12-14, 2022, Dearborn, Michigan}, publisher = {ASME}, isbn = {978-0-7918-8627-4}, doi = {10.1115/SMASIS2022-90742}, pages = {6}, abstract = {Adaptive surface microstructures are used extensively in nature to control various surface properties such as wettability, adhesion, self-cleaning, drag reduction, etc. Regulation of these properties can be achieved with the appropriate employment of a multitude of smart materials, whose characteristics/response can be controlled by noncontact stimuli, e.g., light, heat, or magnetic field. One of the very promising magneto-regulable smart materials are magnetoactive elastomers (MAEs). They are comprised of a compliant polymer matrix with embedded micrometer-sized ferromagnetic particles. The particles interact with each other and a magnetic field. This results in remarkable tunability of the physical properties of MAEs. This paper reports a fast, resilient, and tailored method for direct surface micromachining of MAEs that enables micro-structuring without mechanical contact between the tool and the material, bypassing the usual constraints of conventional fabrication methods. It is shown that it is possible to fabricate a large variety of different microstructure geometries whose precision is limited predominantly by the size of magnetic particles. Lamellar structures with a high aspect ratio (up to 6:1) oriented either perpendicularly to the surface, can be strongly bent by applying magnetic fields in the range of 0-250 mT.}, language = {en} } @misc{KrieglKravanjaHribaretal., author = {Kriegl, Raphael and Kravanja, Gaia and Hribar, Luka and Jezeršek, Matija and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail}, title = {Characterization of Wetting Properties of Magnetoactive Elastomer Surfaces}, series = {Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) - 2023, September 11-13, 2023 Austin, Texas, USA}, journal = {Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) - 2023, September 11-13, 2023 Austin, Texas, USA}, publisher = {The American Society of Mechanical Engineers}, address = {New York, USA}, isbn = {978-0-7918-8752-3}, doi = {10.1115/SMASIS2023-110998}, abstract = {Commercially available contact angle (CA) measuring devices usually do not allow for the application of magnetic fields to the sample under test. A setup for measuring the CA of liquids on magnetosensitive surfaces has been developed specifically for investigating the surfaces of magnetoactive elastomers (MAEs). The addition of a programmable linear stage, which moves a permanent magnet, allows for fine control of the magnetic field applied to the MAE without the need for large and power-consuming electromagnets. Paired with a custom control and evaluation software, this measurement setup operates semiautomatically, limiting operator error and increasing precision, speed, as well as repeatability of static and dynamic CA measurements for different magnetoactive materials. The software is equipped with robust droplet fitting algorithms to avoid experimental challenges arising with soft magnetoactive materials, such as the curling of sample edges or diffuse non-reflective surfaces. Several application examples on MAE surfaces, both processed and unprocessed, are presented.}, language = {en} } @article{GlavanBelyaevaDrevenšek‐Oleniketal., author = {Glavan, Gašper and Belyaeva, Inna A. and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail}, title = {Experimental study of longitudinal, transverse and volume strains of magnetoactive elastomeric cylinders in uniform magnetic fields}, series = {Journal of Magnetism and Magnetic Materials}, volume = {579}, journal = {Journal of Magnetism and Magnetic Materials}, publisher = {Elsevier}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2023.170826}, abstract = {Magnetoactive elastomers (MAEs) are promising materials for realization of magnetic field-controlled soft actuators. Herein, a systematic investigation of magnetic field-induced macroscopic deformations of soft MAE cylinders with a diameter of 15 mm in uniform quasi-static magnetic fields directed parallel to the cylinder's axis is reported. The measurements were based on image processing. Thirty-six MAE samples differing in the weight fraction of the iron filler (70 wt\%, 75 wt\% and 80 wt\%), alignment of filling particles, and the aspect ratio (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2) were fabricated. MAE cylinders exhibited high relative change in height (up to 35\% in the field of 485 kA/m) and lateral contraction. The dependence of the maximum extensional strain on the aspect ratio was obtained and compared with theoretical considerations. A concave dent was formed on the free circular base in magnetic fields. This concavity was characterized experimentally. A significant volumetric strain of the order of magnitude of 10\% was calculated in MAEs for the first time. In consequently repeated magnetization cycles, the remanent extensional strain significantly increased after each cycle. The results are qualitatively discussed in the framework of the modern views on the magnetically induced macroscopic deformations of MAEs. The directions of further research are outlined.}, language = {en} } @article{HoernerKrykanovChashinetal., author = {H{\"o}rner, Eduard and Krykanov, Ivan M. and Chashin, Dmitri V. and Fetisov, Yuri K. and Fetisov, Leonid Y. and Shamonin (Chamonine), Mikhail}, title = {Magnetoelectric characteristics of cobalt-iron alloy-lead zirconate titanate bilayer planar structures}, series = {International Journal of Materials Research}, volume = {103}, journal = {International Journal of Materials Research}, number = {11}, publisher = {De Gruyter}, doi = {10.3139/146.110776}, abstract = {The characteristics of both direct and converse magnetoelectric (ME) interactions in bilayer composite structures comprising layers of a commercially available magnetostrictive permendur CoFe alloy and different piezoelectric PZT ceramics are investigated in detail by the method of harmonic field modulation. It is shown that, given the optimum DC magnetic bias field, a high piezomagnetic coefficient in the alloy leads to increased efficiency of ME interactions. The resonant behavior of frequency dependencies of the magnetoelectric voltage is explained by excitation of bending and planar mechanical oscillations in the structures. The results are of interest for developing highly sensitive AC magnetic field sensors and magnetoelectric transducers for energy harvesting from mechanical vibrations.}, language = {de} } @article{StrausKokotKravanjaetal., author = {Straus, Izidor and Kokot, Gašper and Kravanja, Gaia and Hribar, Luka and Kriegl, Raphael and Shamonin (Chamonine), Mikhail and Jezeršek, Matija and Drevenšek-Olenik, Irena}, title = {Dynamically tunable lamellar surface structures from magnetoactive elastomers driven by a uniform magnetic field}, series = {Soft Matter}, volume = {Vol. 19}, journal = {Soft Matter}, publisher = {Royal Society of Chemistry}, doi = {10.1039/D3SM00012E}, pages = {3357 -- 3365}, abstract = {Stimuli responsive materials are key ingredients for any application that requires dynamically tunable or on-demand responses. In this work we report experimental and theoretical investigation of magnetic-field driven modifications of soft-magnetic elastomers whose surface was processed by laser ablation into lamellar microstructures that can be manipulated by a uniform magnetic field. We present a minimal hybrid model that elucidates the associated deflection process of the lamellae and explains the lamellar structure frustration in terms of dipolar magnetic forces arising from the neighbouring lamellae. We experimentally determine the magnitude of the deflection as a function of magnetic flux density and explore the dynamic response of lamellae to fast changes in a magnetic field. A relationship between the deflection of lamellae and modifications of the optical reflectance of the lamellar structures is resolved.}, language = {en} } @article{StrausKravanjaHribaretal., author = {Straus, Izidor and Kravanja, Gaia and Hribar, Luka and Kriegl, Raphael and Jezeršek, Matija and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena and Kokot, Gašper}, title = {Surface Modification of Magnetoactive Elastomers by Laser Micromachining}, series = {Materials}, volume = {2024}, journal = {Materials}, number = {17 / 7}, publisher = {MDPI AG}, address = {Basel, Switzerland}, doi = {10.3390/ma17071550}, pages = {12}, abstract = {It has been recently demonstrated that laser micromachining of magnetoactive elastomers is a very convenient method for fabricating dynamic surface microstructures with magnetically tunable properties, such as wettability and surface reflectivity. In this study, we investigate the impact of the micromachining process on the fabricated material's structural properties and its chemical composition. By employing scanning electron microscopy, we investigate changes in size distribution and spatial arrangement of carbonyl iron microparticles dispersed in the polydimethylsiloxane (PDMS) matrix as a function of laser irradiation. Based on the images obtained by a low vacuum secondary electron detector, we analyze modifications of the surface topography. The results show that most profound modifications occur during the low-exposure (8 J/cm^2) treatment of the surface with the laser beam. Our findings provide important insights for developing theoretical models of functional properties of laser-sculptured microstructures from magnetoactive elastomers.}, language = {en} } @inproceedings{KrieglJezeršekKravanjaetal., author = {Kriegl, Raphael and Jezeršek, Matija and Kravanja, Gaia and Hribar, Luka and Kokot, Gašper and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail}, title = {Characterization of Tunable Rebound Properties of Microstructured Magnetoactive Elastomers}, series = {ASME 2024 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS), September 9-11, 2024, Atlanta, Georgia, USA}, booktitle = {ASME 2024 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS), September 9-11, 2024, Atlanta, Georgia, USA}, publisher = {American Society of Mechanical Engineers}, address = {New York, USA}, isbn = {978-0-7918-8832-2}, doi = {10.1115/SMASIS2024-139154}, abstract = {We present a novel method to control the rebounding behavior of small mm-sized solid balls by employing magnetoactive elastomers (MAEs) with microstructured surfaces. An MAE is a composite material consisting of μm-sized ferromagnetic particles dispersed in a soft elastomer (e.g., polydimethylsiloxane) matrix. In the act of rebounding, the ball hits an MAE surface and bounces back. The MAE samples contained 75 wt.\% of iron. This composite material is known to respond to an applied magnetic field with increased stiffness (due to the magnetorheological effect) and plasticity. To adjust the rebound properties, the top layer of the MAE material was additionally modified by micromachining lamellar structures with different dimensions on the 100 μm scale via laser ablation. Due to the resulting high aspect ratio, these surface structures were sensitive to the magnetic field direction. The lamellas could stand up straight or lay down flat. The rebound behavior was evaluated by using a custom build apparatus that facilitates dropping of the balls in a precise and repeatable manner. A ball was dropped from different heights. The ball trajectory was captured with a high-speed camera to investigate the rebound properties. The recorded video was processed using a custom software written in Python. The experimental procedure and data processing algorithms are presented in detail. The results for the samples with different geometrical dimensions are provided as examples. It is made evident that the magnetic field influences the rebound properties of small non-magnetic balls impinging microstructured MAE surfaces. The change in surface topography is an effective way to control the ball rebound. The fabrication flexibility in geometrical dimensions of surface microstructures opens a convenient way to tune the desired response to magnetic fields. The presented idea may find applications in impact mitigation or small-scale sorting machinery, e.g. for recycling.}, language = {en} } @article{LovšinBrandlGlavanetal., author = {Lovšin, Matija and Brandl, Dominik and Glavan, Gašper and Belyaeva, Inna A. and Cmok, Luka and Coga, Lucija and Kalin, Mitjan and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena}, title = {Reconfigurable Surface Micropatterns Based on the Magnetic Field-Induced Shape Memory Effect in Magnetoactive Elastomers}, series = {Polymers}, volume = {13}, journal = {Polymers}, number = {24}, publisher = {MDPI}, doi = {10.3390/polym13244422}, abstract = {A surface relief grating with a period of 30 mu m is embossed onto the surface of magnetoactive elastomer (MAE) samples in the presence of a moderate magnetic field of about 180 mT. The grating, which is represented as a set of parallel stripes with two different amplitude reflectivity coefficients, is detected via diffraction of a laser beam in the reflection configuration. Due to the magnetic-field-induced plasticity effect, the grating persists on the MAE surface for at least 90 h if the magnetic field remains present. When the magnetic field is removed, the diffraction efficiency vanishes in a few minutes. The described effect is much more pronounced in MAE samples with larger content of iron filler (80 wt\%) than in the samples with lower content of iron filler (70 wt\%). A simple theoretical model is proposed to describe the observed dependence of the diffraction efficiency on the applied magnetic field. Possible applications of MAEs as magnetically reconfigurable diffractive optical elements are discussed. It is proposed that the described experimental method can be used as a convenient tool for investigations of the dynamics of magnetically induced plasticity of MAEs on the micrometer scale.}, language = {en} } @inproceedings{HolthausHagedornKlanketal., author = {Holthaus, Carsten and Hagedorn, Oliver and Klank, Michael and Shamonin (Chamonine), Mikhail and Trifonov, A. and D{\"o}tsch, Horst}, title = {Preparation and Characterization of Sensitive Magnetic Garnet Films for MOI Applications}, series = {Magneto-Optical Imaging. Proceedings of the NATO Advanced Research Workshop on Magneto-Optical Imaging, {\O}ystese, Norway, 28 - 30 August 2003}, booktitle = {Magneto-Optical Imaging. Proceedings of the NATO Advanced Research Workshop on Magneto-Optical Imaging, {\O}ystese, Norway, 28 - 30 August 2003}, publisher = {Kluwer}, address = {Dodrecht}, doi = {10.1007/978-94-007-1007-8_42}, pages = {329 -- 336}, abstract = {Magnetic garnet films prepared by liquid phase epitaxy on paramagnetic substrates of gadolinium gallium garnet are currently used for the imaging of magnetic field distributions. This application is based on the Faraday rotation which can be strongly enhanced by bismuth incorporation. For gray scale imaging the plane of the sensor film should be an easy plane of magnetization so that no domains nucleate. However, incorporation of bismuth induces a strong positive uniaxial anisotropy perpendicular to the film plane, especially if films of [111] orientation are used. To counteract this unwanted behavior neodymium and/or praseodymium are substituted in addition to bismuth. These two elements cause a very strong negative anisotropy. This is tested experimentally by growing series of garnet films with gradually changing composition and growth parameters.}, language = {en} } @article{BodnarukBrunhuberKalitaetal., author = {Bodnaruk, Andrii V. and Brunhuber, Alexander and Kalita, Viktor M. and Kulyk, Mykola M. and Snarskii, Andrei A. and Lozenko, Albert F. and Ryabchenko, Sergey M. and Shamonin (Chamonine), Mikhail}, title = {Temperature-dependent magnetic properties of a magnetoactive elastomer: Immobilization of the soft-magnetic filler}, series = {Journal of Applied Physics}, volume = {123}, journal = {Journal of Applied Physics}, number = {11}, publisher = {AIP Publishing}, doi = {10.1063/1.5023891}, abstract = {The magnetic properties of a magnetoactive elastomer (MAE) filled with mu m-sized soft-magnetic iron particles have been experimentally studied in the temperature range between 150 K and 310 K. By changing the temperature, the elastic modulus of the elastomer matrix was modified, and it was possible to obtain magnetization curves for an invariable arrangement of particles in the sample and in the case when the particles were able to change their position within the MAE under the influence of magnetic forces. At low (less than 220 K) temperatures, when the matrix becomes rigid, the magnetization of the MAE does not show a hysteresis behavior, and it is characterized by a negative value of the Rayleigh constant. At room temperature, when the polymer matrix is compliant, a magnetic hysteresis exists where the dependence of the differential magnetic susceptibility on the magnetic field exhibits local maxima. The appearance of these maxima is explained by the elastic resistance of the matrix to the displacement of particles under the action of magnetic forces.}, language = {en} } @misc{ScharfenbergMottokArtmannetal., author = {Scharfenberg, Georg and Mottok, J{\"u}rgen and Artmann, Christina and Hobelsberger, Martin and Paric, Ivan and Großmann, Benjamin and Pohlt, Clemens and Wackerbarth, Alena and Pausch, Uli and Heidrich, Christiane and Fadanelli, Martin and Elsner, Michael and P{\"o}cher, Daniel and Pittroff, Lenz and Beer, Stefan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Sterner, Michael and Thema, Martin and Muggenthaler, Nicole and Lenck, Thorsten and G{\"o}tz, Philipp and Eckert, Fabian and Deubzer, Michael and Stingl, Armin and Simsek, Erol and Kr{\"a}mer, Stefan and Großmann, Benjamin and Schlegl, Thomas and Niedersteiner, Sascha and Berlehner, Thomas and Joblin, Mitchell and Mauerer, Wolfgang and Apel, Sven and Siegmund, Janet and Riehle, Dirk and Weber, Joachim and Palm, Christoph and Zobel, Martin and Al-Falouji, Ghassan and Prestel, Dietmar and Scharfenberg, Georg and Mandl, Roland and Deinzer, Arnulf and Halang, W. and Margraf-Stiksrud, Jutta and Sick, Bernhard and Deinzer, Renate and Scherzinger, Stefanie and Klettke, Meike and St{\"o}rl, Uta and Wiech, Katharina and Kubata, Christoph and Sindersberger, Dirk and Monkman, Gareth J. and Dollinger, Markus and Dembianny, Sven and K{\"o}lbl, Andreas and Welker, Franz and Meier, Matthias and Thumann, Philipp and Swidergal, Krzysztof and Wagner, Marcus and Haug, Sonja and Vernim, Matthias and Seidenst{\"u}cker, Barbara and Weber, Karsten and Arsan, Christian and Schone, Reinhold and M{\"u}nder, Johannes and Schroll-Decker, Irmgard and Dillinger, Andrea Elisabeth and Fuchshofer, Rudolf and Monkman, Gareth J. and Shamonin (Chamonine), Mikhail and Geith, Markus A. and Koch, Fabian and {\"U}hlin, Christian and Schratzenstaller, Thomas and Saßmannshausen, Sean Patrick and Auchter, Eberhard and Kriz, Willy and Springer, Othmar and Thumann, Maria and Kusterle, Wolfgang and Obermeier, Andreas and Udalzow, Anton and Schmailzl, Anton and Hierl, Stefan and Langer, Christoph and Schreiner, Rupert}, title = {Forschungsbericht 2015}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-00-048589-3}, doi = {10.35096/othr/pub-1386}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13867}, language = {de} }