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The dynamic characteristics of a steel/CFRP (carbon fiber reinforced plastic) drive shaft were studied. finite element analysis (FEA) and an experiment were carried out to investigate the natural frequencies and mode shapes. The results of the experiment verified the effectiveness of the finite element model. At the same time, the FEA was used to predict the dynamic characteristics of the shaft for different stacking sequences, fiber orientation angles, and layer thicknesses. The results show that the natural frequency increases with decreasing fiber orientation angles. And the positive and negative stacking sequences are helpful to improve natural frequency. The layer thicknesses and stacking sequences will have a pronounced effect in a specific size of the shaft.

The single-phase multiferroic Bi 5 Fe 1−x Ni x Ti 3 O 15 (BFNT-x, x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized by a sol-gel auto-combustion method, and their microstructures, ferroelectric, magnetic, and dielectric properties were investigated in detail. All samples belong to layer-perovskited Aurivillius phase containing four perovskite units sandwiched between two Bi-O layers. Ni substitution can not only improve ferroelectricity but also enhance the magnetic properties. The BFNT-0.2 sample shows the largest remnant polarization (2P r ∼ 11.6 µC/cm 2 ) and the highest remnant magnetization (2M r ∼ 0.244 emu/g). The enhancement of the magnetic properties may mainly originate from the spin canting of Fe/Ni-O octahedra via Dzyaloshinskii-Moriya (DM) interaction. In order to explore the influence of valance state of magnetic ions on the properties, the x-ray photoelectron spectroscopy was carried out. Furthermore, structural, ferroelectric, and magnetic transitions were also investigated.

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