Transition of Membrane/Bending Neural Signals on Transforming Adaptive Shells

Abstract

Sensing and control are essential to achieving the high precision and high performance of modern aerospace structures and systems. The objective of this study is (1) to investigate spatial microscopic neural signal generations and variations from infinitesimal piezoelectric neurons over a transforming cylindrical shell panel at various curvature angles, and (2) to determine dominating signal components resulting from longitudinal/circumferential membrane strains and/or longitudinal/circumferential bending strains at various shell modes. Dynamic equations of cylindrical shells are defined first, followed by free-vibration analysis. Then, mode shape functions and modal spatial strain distributions are used to determine the signal generation of distributed neuron sensors laminated on a linear cylindrical shell panel. To demonstrate signal variations on transforming shells, the microscopic signal generations of infinitesimal piezoelectric sensors or neurons are investigated for three selected discrete curvature angles, i.e. β* = 30°, 90°, and 150°, ofa simply-supported cylindrical shell panel. Evaluating these three cases suggests that (1) the bending induced signal dominates for most modes of shallow shells and (2) the membrane induced signal dominates for lower modes and yields to the bending signal at higher natural modes of deep shells. The shell curvature is the key factor determining this transition from bending dominated behavior to membrane dominated behavior while the curvature increases from 0° to 360°. Once the dominating signal component(s) is identified, one can further select appropriate actuators to effectively counteract and to control specific modes or shapes of shell structures.