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In this research, the propulsion of the proposed jellyfish-inspired mantle undulated propulsion robot (MUPRo) is optimized. To reliably predict the hydrodynamic forces acting on the robot, the proposed nonintrusive reduced-order model (NIROM) based on proper orthogonal decomposition (POD) additionally considers the POD basis that makes an important contribution to the features on the specified boundary. The proposed model establishes a mapping between the parameter-driven motion of the mantle and the evolution of the fluid characteristics around the swimmer. Moreover, to predict new cases where the input needs to be updated, the input of the proposed model is taken from the kinematics of the robot rather than extracted from full-order high-fidelity models. In this paper, it takes approximately 950 s to perform a simulation using the full-order high-fidelity model. However, the computational cost for one prediction with the proposed POD-NIROM is around 0.54 s, of which about 0.2 s is contributed by preprocessing. Compared with the NIROM based on the classic POD method, the proposed POD-NIROM can effectively update the input and reasonably predict the characteristics on the boundary. The analysis of the hydrodynamic performance of the MUPRo pinpoints that, over a certain period and with a certain undulation amplitude, the hydrodynamic force generated by the swinging-like mantle motion (k < 0.5) is greater, outperforming Aequorea victoria in startup acceleration. It is demonstrated that considering a certain power loss and a certain tail beat amplitude, the wave-like mantle motion (k > 0.5) can produce greater propulsion, which means higher propulsion efficiency.

In the current paper, the ageing and de-ageing phenomena in ferroelectric ceramics are modelled by a Landau-type model based on the internal bias field theory. A new phenomenological term for the internal bias electrical field is added into the free energy function to simulate the phenomenon of lattice symmetry during the ageing phenomenon. The simulations for both ageing and de-ageing phenomena are successfully presented in the current paper. The hysteretic behaviours of the ageing and de-ageing phenomena are captured very well by the proposed model.

The static microstructures of square-to-rectangular phase transformations are modeled in the current paper. Governing equations are described by the static Navier equations. The analysis of the simulation has been finished via Legendre wavelets collocation method. Microstructure evolutions of both 2D and 1D shape memory alloy (SMA) are capture well with a certain boundary condition and given mechanical loadings.

An optical device is used to scan a cavity. In a single incident the scanner produces what can be considered a blurred image of the intersection curve between a plane and the cavity. Mathematically the image represents an intensity function and that is obtained by integrating a certain kernel along the intersection curve. We suggest methods to determine the kernel and subsequently the intersection curve given the image. The methodology is tested with some success using an artificial, but realistic kernel and some synthetic images produced by this kernel.

Different from the traditional piezoelectric vibration energy harvesting, a new strategy based on stress-induced polarization switching has been proposed in the current paper. Two related prototypes are presented and the associated advantages and drawbacks have been discussed in detail. It has been demonstrated that, with the assistance of a bias electric field, the robustness of the energy harvesters is improved. Furthermore, the real-space phase-field model has been employed to study the nonlinear hysteretic behavior involved in the proposed energy harvesting process. A substantially larger electric current associated with the stress-induced polarization switching has been demonstrated when compared with that with piezoelectric effect. In addition, the effects of bias electric potential, bias resistance, mechanical boundary conditions, charge leakage and electrodes arrangements have also been investigated by the phase-field simulation, which provides a guidance for future real implementations.

In this paper, an approach based on the nonlinear theory of elastic dynamics is proposed to model microstructure evolution in a shape memory alloy patch. The hysteretic dynamics of the patch at the macro-scale is also modeled by employing Hamilton's principle. The elastic potential energy function is constructed as non-convex on the deviatoric strain, and the governing equations are formulated as two coupled wave equations in terms of the two displacement components. Square to rectangle transformations and rectangle variant re-orientations are modeled by simulating the transitions of system states from one stable branch of the non-convex constitutive relation to another. The proposed model allows a robust implementation of conventional finite element analysis with all typical boundary conditions, but with strong nonlinearity. Numerical results for microstructure evolution caused by boundary stress loadings are presented, laminated structures and needle-like microstructures, which are often observed in experimental investigations, are also obtained. Hysteretic dynamics at the macro-scale is presented together with microstructure evolution.

In the current paper, the hysteretic dynamics and butterfly-shaped behavior of ferroelectric materials are modeled and controlled with a macroscopic differential model inspired by the Landau theory of first-order phase transformations. Hysteretic dynamic behavior of the materials is analyzed as a consequence of orientation switching and the governing equations of the dynamics are formulated as coupled differential equations describing system states switching from one equilibrium state to another. The rate dependence of hysteresis is included in the analysis. A nonlinear feedback strategy is introduced for the linearization and a simple and efficient control strategy is proposed. Comparison of the results obtained with the developed model and their experimental counterparts is presented.