Finite element modelling of macro fiber composite with interdigitated electrode for engineering applications
Smart structures with Macro fiber composite (MFC) piezoelectric actuators have been increasingly applied in engineering. A simple but elaborate finite element model of the smart structures not only can predict vibration dynamics, but also can reduce challenges and computational expense in engineering application. Therefore, a simplified FEM developed to model MFC with interdigitated electrodes (IDEs) is proposed in this paper. A new scheme of FEM for IDEs in MFC is presented. With assuming the poling direction is along the same direction and voltage-progressive electrodes configuration in FEM, the piezoelectric elements employ an equivalent periodic tensile/compressive strain and constant electric potential in the poling direction. Numerical tests of free strain and blocking force and experimental methods are both employed to verify the FEM in this paper. A cantilever aluminum beam with a single MFC actuator is presented. The natural frequencies, vertical deflection and Modal Assurance Criterion (MAC) based on the resonant frequencies show the fidelity of the EF model agree well with experimental measurement. This work presented provides a novel FEM to model MFC for engineering applications such as vibration actuation.
Equivalent force modeling of macro fiber composite actuators integrated into non-homogeneous composite plates for dynamic applications
Smart structures with integrated macro fiber composite (MFC) piezoelectric transducers have been increasingly investigated in engineering. A simple but elaborate system model of such smart structure not only can predict system dynamics, but also can reduce challenges in application. Therefore, the equivalent force (EF) modeling approach is presented to model the plate-type structures with integrated piezoelectric actuators in a semi-analytical fashion: analytical EF is applied to finite element (FE) structural models. The EF is derived from the bending effort balance between the equivalent loads, and the equivalent loads are developed by introducing the spatial distribution into a generalized Hamilton’s principle. The proposed approach is validated by cantilever aluminum beams with integrated MFC actuators and it is consistent with existing alternative approaches from literature. Then, it is validated on a non-homogeneous composite plate for dynamic applications: a laminated composite plate with integrated MFC actuators was manufactured and both an impact test and MFC drive test were elaborately carried out. The modal validation shows the high fidelity of the EF model and the predicted velocity frequency responds functions (FRFs) agree well with experimental measurement. Being applicable to both numerical and analytical modeling approaches, the EF is actually assigned to the out-plane displacement on the structure and distributed along the edges of the actuators. Therefore, it is convenient to use in EF models. The rotational degrees of freedom could also be eliminated in the EF models without losing structure complexity, since they neither link to the electromechanical coupling nor have a significant kinetic contribution to the system.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.