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.
Recent Developments in NASA Piezocomposite Actuator Technology
In this paper, we present an overview of recent progress in the development of the NASA Macro-Fiber Composite (MFC) piezocomposite actuator device. This will include a brief history of the development of the MFC, a description of the standard manufacturing process used to fabricate MFC actuators, and a summary of ongoing MFC electromechanical characterization testing. In addition, we describe the development of a prototype single-crystal piezoelectric MFC device, and compare its performance with MFC actuator specimens utilizing conventional piezoceramic materials.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.