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.
Piezoelectric Fiber Composites with Interdigitated Electrodes
Piezoelectric Fiber Composites were previously introduced as an alternative to monolithic piezoceramic wafers for structural actuation applications. This manuscript was an investigation into the improvement of piezoelectric fiber composite performance through a nonconventional electroding scheme. Two microelectromechanical models were developed that predict the composite properties. These models were used to examine the trends of composite properties versus fiber volume fraction for various constituent materials. Several etched electrode PZT fiber composites, with fiber volume fractions ranging from 7% to 58%, were manufactured and tested. Experimental measurements showed excellent agreement with both the trends and magnitude of model predicted values. The maximum fiber volume fraction composites demonstrated a capacitance (E3 /Eo) of 550, piezoelectric free strain constants (d33 and d31) of 150 pm/V and-70 pm/V, and piezoelectric clamped stress (e33) of 5 C/m2, showing a substantial improvement over previous piezoelectric fiber composites with uniform electrodes. Maximum strain values of 1700 ppm were measured, indicating higher in-plane actuation than monolithic piezoceramics.
Fascism in Britain: A History, 1918-1985
Tracing its origins from shortly after the World War I, this book presents a portrait of fascism in the 1930s. It reassesses Mosley's career, describes the reasons for internment in 1940 and the effect it had on leading fascists, exposes the famous Britons who subscribed to fascism, reveals the ominous re-emergence of the tradition after 1945, and explains its remarkable persistence into the l980s.