Abstract: A system for monitoring the structural integrity of a mechanical structure. The system utilizes a trainable adaptive interpreter such as a neural network to analyze data from the structure to characterize the structure's health. An actuator is attached to the mechanical structure for generating vibrations in response to an input signal. A sensor, also attached to the mechanical structure, senses the vibrations and generates an output signal in response thereto. The sensor output signal is then coupled to a pre-trained adaptive interpreter for generating an output which characterizes the structural integrity of the mechanical structure. The system can provide continual health monitoring of a structural system to detect structural damage and pinpoint probable location of the damage. The system can operate while the structural system is in service there by significantly reducing structural inspection costs.

Abstract: A composite structure of elastic and viscoelastic components in which dynamic loads are effectively damped by repeated transmission through viscoelastic layers. Multiple viscoelastic layers and stiff segmented elastic layers are formed on the outside of a tubular layer of soft elastic material, to provide the damping effect without having to form additional layers inside the tubular layer of soft elastic material. The transition temperatures above which the viscoelastic layers become substantially less stiff may be selected to be different for each layer, to provide increased damping efficiency over a broadened operative temperature range.

Abstract: A structure includes a foundation member and multiple piezoelectric actuator/sensor elements disposed transversely about the structure. The elements are bound to the face of the foundation member to permit force transmission between the elements and the foundation member. The elements include restriction plies orientated oppositely for alternating transverse elements. The elements have a preferred direction of motion and when two adjacent elements are oppositely poled, this relates to a torsional motion between the elements and the foundation member. When four elements are spaced about a cylindrical foundation member and selectively poled, axial, bending and torsional motion between the elements and foundation member is effected.