We extend our high-resolution MRI-based Finite Element (FE) head model, previously presented and validated in [1–3], by considering the heterogeneities of the white matter structures captured through the use of Magnetic Resonance Elastography (MRE). This approach imparts more sophistication to our numerical model and yields results that more closely match experimental results. It is found that the peak pressure more closely matches the experiments as compared to the heterogeneous case. Qualitatively, we find differences in stress wave propagation near the corpus callosum and the corona radiata, which are stiffer on average than the global white matter. We are able to study the effects of these stiff structures on transient stress wave propagation within the cerebrum, something that cannot be done with a homogenized material model.

Tissues of the brain, especially white matter, are extremely heterogeneous - with constitutive response varying spatially. In this paper, we implement a high-resolution Finite Element (FE) head model where heterogeneities of white matter structures are introduced through Magnetic Resonance Elastography (MRE) experiments. Displacement of white matter under shear wave excitation is captured and the material properties determined though an inversion algorithm are directly used in the FE model. This approach is found to improve model predictions when compared to experimental results. In the first place, responses in the cerebrum near stiff structures such as the corpus callosum and corona radiata are markedly different compared with a homogenized material model. Additionally, the heterogeneities introduce additional attenuation of the shear wave due to wave scattering within the cerebrum.

Silicone RTV-based engineering rubber composite products have been widely used for several applications in various fields as a major component such as structure, automotive, and medical. In its application, the rubber composite product is placed in an open area that is directly exposed to sunlight and rain. It has a significant negative impact on changes in chemical and rheological properties, making the product life of rubber composite products shorter. Therefore, in this study, changes in the chemical and rheological properties of both isotropic and anisotropic magnetorheological elastomer (MRE) treated with accelerated weathering were studied compared to untreated specimens with specimens that had been treated. MRE specimens with 40% by weight CIP were prepared with no current excitation and another sample were made under 1.5 T of magnetic flux density. Each specimen was treated in an accelerated weathering machine Q-Sun Xe-1 Xenon Test Chamber with a UV light exposure cycle for 102 minutes and 18 minutes of UV light combined with water spray for 24 hours followed by a condensation cycle of 4 hours in a dark period. Material characterization was carried out using FTIR and Rheometer to determine the changes in chemical and rheological properties. The morphological analysis results showed that the surface was rough and more cavities occurred after being given weather treatment. Rheometer test results showed a decrease in storage modulus in each MRE specimen that had been treated compared to untreated MRE specimens. Meanwhile, FTIR testing showed a change in wave peak between untreated and treated MRE specimens.

This study investigates the dynamic characteristics of Natural Rubber (NR)/Polybutadiene Rubber (PBR) based hybrid magnetorheological elastomer (MRE) sandwich composite beams through numerical simulations and finite element analysis, employing Reddy's third-order shear defor-mation theory. Four distinct hybrid MRE sandwich configurations were examined. The validity of finite element simulations was confirmed by comparing them with results from magnetorheo-logical (MR) fluid-based composites. Further, parametric analysis explored the influence of magnetic field intensity, boundary conditions, ply orientation, and core thickness on beam vi-bration responses. Results reveal a notable 10.4% enhancement in natural frequencies in SC4-based beams under a 600mT magnetic field with clamped-free boundary conditions, attributed to in-creased PBR content in MR elastomer cores. However, higher magnetic field intensities result in slight frequency decrements due to filler particle agglomeration. Additionally, augmenting magnetic field intensity and magnetorheological content under clamped-free conditions improves the loss factor by 66% to 136%, presenting promising prospects for advanced applications. This research contributes to a comprehensive understanding of dynamic behavior and performance enhancement in hybrid MRE sandwich composites, holding significant implications for engi-neering applications. Furthermore, this investigation provides valuable insights into the intricate interplay between magnetic field effects, composite architecture, and vibration response.