Self-assembly of self-propelled magnetic grains

In this work, we study bidisperse mixtures of self-propelled magnetic particles of different shapes via discrete element method simulations. We show how these particles self-assemble into clusters and how these clusters depend on the ratio of the mixture, the magnetic interaction, and the shape of the grains. It is found that the mix ratio of the system controls the cluster size. Besides, the intensity of the magnetic dipoles and the shape of the grains in the mixture rule the average number of neighbors in contact and the shape of the clusters. By varying the intensity of the interactions, globular, linear and branched clusters were obtained.

Free vibration analysis of magneto-electro-elastic cylindrical composite panel reinforced by various distributions of CNTs with considering open and closed circuits boundary conditions based on FSDT

In this paper, free vibration analysis of magneto-electro-elastic (MEE) cylindrical composite panel reinforced by various distributions of carbon nanotubes (CNTs) considering open and closed circuits boundary conditions based on the first order shear deformation theory (FSDT) is carried out. Carbon nanotubes (CNTs) in Poly-vinylidene fluoride (PVDF) matrix are arranged and different distribution patterns of CNTs including uniform distribution (UD), FG-V, FG-A, FG-X and FG-O are employed. The Young’s and shear moduli are obtained using the extended mixture rule. Also, the material properties of magneto-electric fiber reinforced composite are estimated by mixture rule. By employing energy method and Hamilton’s principle, the equations of motion for cylindrical composite panel reinforced by CNTs are derived. In this paper, the effects of the volume fraction, various distributions of CNTs including uniform and functionally graded (FG) distributions, angle orientation, two elastic foundation parameters, aspect ratio (length-to-thickness ratio), radius-to-thickness ratio, and the multi-physical fields with open and closed circuits boundary conditions on the natural frequency of MEE cylindrical composite panel are considered. These effects play an important role on the natural frequencies. Moreover, the numerical results of this research can be used to manufacturing process design and optimization MEE cylindrical composite panel under multi-physical fields and the previous results can be used in order to prevent the resonance phenomenon.

Effects of Mass Ratio of Phenolic Fiber to Quartz Fiber on the Ablative Properties of Hybrid Fabric Reinforced Composites

Phenolic-quartz hybrid fabric reinforced phenolic resin composites were fabricated by compression molding and the mass ratios of phenolic fiber to quartz fiber were 1:3, 1:1 and 3:1, respectively. The ablative properties of the composite specimens were quantitatively evaluated by oxyacetylene flame test and exhaust plume ablative test with a small liquid motor (EPSLM). The effects of mass ratio of phenolic fiber to quartz fiber on the ablative properties of the composites were investigated. In the oxyacetylene flame test, the mass loss rate of the composite specimens, which can be predicted by the mixture rule, increased with rising content of phenolic fiber. However, the mixture rule was not applicable to predict the mass loss of the composite specimen in EPSLM. The mass loss of the hybrid composite specimens decreased with increasing content of phenolic fiber. As suggested by the patterns and microstructures of the char after ablation, it is useful to stabilize the char by adding phenolic fiber, and the resistance of the hybrid composite specimens to heat-flow erosion was evidently augmented when the mass ratio of phenolic fiber to quartz fiber was higher than 1:1.