Global and Local Dynamics of a Bistable Asymmetric Composite Laminated Shell

As bistable composite laminated plate and shell structures are often exposed to dynamic environments in practical applications, the global and local dynamics of a bistable asymmetric composite laminated shell subjected to the base excitation is presented in this paper. Temperature difference, base excitation amplitude, and detuning parameters are discussed. With the change of temperature difference, the super-critical pitchfork bifurcation occurs. Three equilibrium solutions corresponding to three equilibrium configurations (two stable configurations and one unstable configuration) can be obtained. With the increase of excitation amplitude, local and global dynamics play a leading role successively. The global dynamics between the two stable configurations behave as the periodic vibration, the quasi-periodic vibration, the chaotic vibration and dynamic snap-through when the excitation amplitude is large enough. The local dynamics that are confined to a single stable configuration behave as 1:2 internal resonance, saturation and permeation when the excitation amplitude is small. Dynamic snap-through and large-amplitude vibrations with two potential wells for the global dynamics will lead to a broad application prospect of the bistable asymmetric composite laminated shell in energy harvesting devices.

Analysis of periodic laminated fiber-reinforced composite beams in free vibration

The dynamic behavior of solid structures is an important aspect that must be considered in the design phase to ensure that the designed structure will have desired response under external excitation. Periodic structures offer various design possibilities that can tailor the dynamic behavior of the structure to match the desired response under a given applied excitation. The use of laminated fiber-reinforced composite materials in periodic structures further increases the design degrees of freedom by introducing new design parameters, such as the number of plies in each periodic patch and their fiber-orientation angles. In this article, the classical lamination theory is integrated with the forward approach of the wave finite element method to analyze periodic fiber-reinforced composite beams in flexural vibration. Since Euler–Bernoulli’s beam theory is used, the proposed approach is much simpler and computationally efficient than using laminated shell finite elements. The article shows the effects of the number of periodic cells, the segment length ratio, the number of plies in each periodic patch, and their fiber-orientation on the first stop band of the beam. The results reported can guide the design of such structures to attenuate vibration amplitudes at specific target frequency bands and avoid undesired dynamic responses. Results have been validated in the 0–2000 Hz frequency range by comparison with finite element laminated shell models.

Influence of Piezoelectric Performance on Nonlinear Dynamic Characteristics of MFC Shells

Based on the structures of unmanned aerial vehicle (UAV) wings, nonlinear dynamic analysis of macrofiber composite (MFC) laminated shells is presented in this paper. The effects of piezoelectric properties and aerodynamic forces on the dynamic stability of the MFC laminated shell are studied. Firstly, under the flow condition of ideal incompressible fluid, the thin airfoil theory is employed to calculate the effects of the mean camber line to obtain the circulation distribution of the wings in subsonic air flow. The steady aerodynamic lift on UAV wings is derived by using the Kutta–Joukowski lift theory. Then, considering the geometric nonlinearity and piezoelectric properties of the MFC material, the nonlinear dynamic model of the MFC laminated shell is established with Hamilton’s principles and the Galerkin method. Next, the effects of electric field, external excitation force, and nonlinear parameters on the stability of the system are studied under 1 : 1 internal resonance and the effects of material parameters on the natural frequency of the structure are also analyzed. Furthermore, the influence of the aerodynamic forces and electric field on the nonlinear dynamic responses of MFC laminated shells is discussed by numerical simulation. The results indicate that the electric field and external excitation have great influence on the structural dynamic responses.