Micro-piezothermoelastic behavior and distributed sensing/control of nonlinear structronic beam and paraboloidal shell systems.

摘要

Piezothermoelastic structures are distributed parameter systems (DPS) that couple the mechanical field, electric field and thermal field. Modeling and analyzing the elastic and piezoelectric material laminated structronic (structure + electronic) systems by their electrical analogies are rather challenging in the system design and vibration control area. This dissertation uses theoretical, numerical and electronic circuit modeling methods to investigate the micro-piezothermoelastic behavior of nonlinear structronic beam and paraboloidal shell systems.; Structronic beam systems with fixed-free and simply-simply supported boundary conditions are studied. Nonlinear effect, axial oscillation influence and thermal effect; displacement, velocity and PID feedback control methods are investigated. The new, improved electronic circuit modeling method that uses active components is verified to have good modeling accuracy by the comparison with numerical and theoretical results.; Equations of motion for paraboloidal shells of revolution are derived. A mode shape function for simply supported paraboloidal shells is proposed and verified by the experimental data found in literature. Micro-sensing and control characteristics of paraboloidal shells with simply supported boundary and free boundary are investigated. Microscopic characteristics of distributed sensing are revealed by detailed signal components of both the distributed modal voltages generated by infinitesimal small sensing neurons and the sensing signals generated by segmented sensor patches. Nonlinear contribution to distributed sensing is also evaluated. Detailed control force components are studied. Modal control forces of actuator patches and closed-loop control performances are investigated. Different sensor/actuator sizes and locations, shell geometry parameters (shallower/deeper, thinner/thicker) and natural modes are studied. Equivalent electronic model for the structronic paraboloidal shell system is also designed.; Optimal control method is applied to the state feedback control of structronic paraboloidal shell systems. Its advantages are shown by the comparison with the control effect using other parameters at the same control gain cost. Thermal effects of different temperature fields (transverse/surface, linear/quadratic) to structronic beam and shell systems are investigated. Distributed actuators are designed to counteract the thermal force of piezothermoelastic paraboloidal shell structure.