Abstract: A method of analyzing a structure includes producing a finite element model of the structure having fibers embedded therein, and including one or more plies. This may include performing a discretization of a digital model of the structure in which each ply of the one or more plies is represented by a mesh of finite elements aligned with a direction of uni-directional fibers embedded in the ply. Producing the finite element model may also include adding a fiber-aligned intraply interface element between selected adjacent finite elements in the mesh of each ply to capture potential intraply failure modes. And the method may include performing a finite element method (FEM) failure analysis of the finite element model under a load, with the FEM failure analysis producing an output that indicates an extent of any of the potential intraply failure modes that result from the finite element model under the load.

Abstract: A method of forming an energy harvesting device comprises supporting an outer peripheral edge of a disc spring using a support element that allows oscillations of the disc spring. A first preload force is applied to the disc spring and directed along its axial center. During application of the first preload force, a piezoelectric material is fixedly secured with a surface of the disc spring. A second preload force is applied to the disc spring to thereby provide a predetermined reduction of a stiffness of the disc spring. The reduction of the stiffness corresponds to an increased sensitivity to low-frequency components of vibrational energy received by the energy harvesting device.

Abstract: A method of analyzing a structure includes producing a finite element model of the structure having fibers embedded therein, and including one or more plies. This may include performing a discretization of a digital model of the structure in which each ply of the one or more plies is represented by a mesh of finite elements aligned with a direction of uni-directional fibers embedded in the ply. Producing the finite element model may also include adding a fiber-aligned intraply interface element between selected adjacent finite elements in the mesh of each ply to capture potential intraply failure modes. And the method may include performing a finite element method (FEM) failure analysis of the finite element model under a load, with the FEM failure analysis producing an output that indicates an extent of any of the potential intraply failure modes that result from the finite element model under the load.

Abstract: An energy harvesting apparatus and method that is especially well suited for harvesting low frequency broadband vibration energy from a vibrating structure is presented. The apparatus includes a pair of disc springs that are arranged in an opposing relationship. A threaded fastening member and a threaded nut extend through apertures in each of the disc springs and enable a predetermined preload force to be applied to the disc springs. The preload effectively “softens” the disc springs, thus heightening the sensitivity of the disc springs to low frequency, low amplitude vibration energy. A piezoelectric material ring is secured to each of the disc springs. Each piezoelectric material ring experiences changes in strain as its associated disc spring deflects in response to vibration energy experienced from a vibrating structure.

Abstract: A sensor device for monitoring and testing for potential corrosion of structural elements is disclosed comprising a soluble material disposed adjacent to at least one conductor in a transmission line that reacts to the presence of moisture causing a detectable change in an electrical property of the conductor. The conductor may comprise a conductive ink that is disrupted when the soluble material dissolves beneath it. Alternately, the nonconductive soluble membrane may separate two conductors and moisture causes a disruption in the soluble membrane allowing the two conductors to short. Detected changes in the electrical properties of the one or more conductors can be used to indicate potential corrosion or structural imparement in the structural element. Connection to the sensor device may be through a connector or using a wireless reader which remotely energizes the sensor device comprising one or more RFID chips.

Abstract: An illustrative embodiment of a temperature-activated voltage generator includes a generator housing having a housing interior; a flexible, temperature-sensitive bimetallic element disposed in the housing interior; and a piezoelectric element carried by the generator housing. The bimetallic element is positional between a first position wherein the bimetallic element disengages the piezoelectric element and a second position wherein the bimetallic element engages the piezoelectric element. Electrical voltage output leads are electrically connected to the piezoelectric element. A voltage-generating method is also disclosed.

Abstract: An illustrative embodiment of a temperature-activated voltage generator includes a generator housing having housing interior; a flexible, temperature-sensitive bimetallic element disposed in the housing interior; and a piezoelectric element carried by the generator housing. The bimetallic element is positional between first position wherein the bimetallic element disengages the piezoelectric element, and a second position wherein the bimetallic element engages the piezoelectric element. Electrical voltage output leads are electrically connected to the piezoelectric element. A voltage-generating method is also disclosed.

Abstract: A structural health management device, system and method are provided for facilitating the inspection of a structure, such as in accordance with a condition-based maintenance strategy. A structural health management device may include a radio frequency identification (RFID) tag and at least one sense line communicably coupled to the RFID tag and configured to extend at least partially along a workpiece. The sense line may be formed of different materials depending upon the objective of the inspection. The RFID tag may include processing circuitry and an antenna configured to facilitate offboard communication. The processing circuitry may be configured to interrogate the at least one sense line to determine a change in continuity which is indicative of a change in the structural health of the workpiece. The structural health management device may therefore detect the onset of structural issues in a timely manner.

Abstract: An illustrative embodiment of a temperature-activated voltage generator includes a generator housing having a housing interior; a flexible, temperature-sensitive bimetallic element disposed in the housing interior; and a piezoelectric element carried by the generator housing. The bimetallic element is positional between a first position wherein the bimetallic element disengages the piezoelectric element and a second position wherein the bimetallic element engages the piezoelectric element. Electrical voltage output leads are electrically connected to the piezoelectric element. A voltage-generating method is also disclosed.

Abstract: An illustrative embodiment of a temperature-activated voltage generator includes a generator housing having a housing interior; a flexible, temperature-sensitive bimetallic element disposed in the housing interior; and a piezoelectric element carried by the generator housing. The bimetallic element is positional between a first position wherein the bimetallic element disengages the piezoelectric element and a second position wherein the bimetallic element engages the piezoelectric element. Electrical voltage output leads are electrically connected to the piezoelectric element. A voltage-generating method is also disclosed.

Abstract: A temperature sensor is described that includes a base, a first set of posts attached to the base having a first coefficient of thermal expansion, a second set of posts attached to the base and having a second coefficient of thermal expansion, and two substantially parallel conductive plates forming a capacitor. The first of the conductive plates is fixed to the first set of posts and the second of the conductive plates is fixed to the second set of posts. Temperature changes cause the first set of posts and the second set of posts to elongate at different rates, thereby changing a distance between the conductive plates and therefore the resulting capacitance. A system and method are also described for determining resonant frequency associated with the sensor which correlates to the temperature at the sensor when multiple sensors are networked across a system.

Abstract: A structural health management device, system and method are provided for facilitating the inspection of a structure, such as in accordance with a condition-based maintenance strategy. A structural health management device may include a radio frequency identification (RFID) tag and at least one sense line communicably coupled to the RFID tag and configured to extend at least partially along a workpiece. The sense line may be formed of different materials depending upon the objective of the inspection. The RFID tag may include processing circuitry and an antenna configured to facilitate offboard communication. The processing circuitry may be configured to interrogate the at least one sense line to determine a change in continuity which is indicative of a change in the structural health of the workpiece. The structural health management device may therefore detect the onset of structural issues in a timely manner.

Abstract: Structural health monitoring apparatuses and methods are disclosed. One or more structural health sensors may be used to disconnect and/or connect one or more RFID chips to an antenna such that wireless communication with the one or more RFID chips (or the absence of wireless communication) through the antenna indicates the structural health status. Example structural health sensors may be moisture detecting or fracture detecting. A remote reader may be used to establish the wireless communication with the one or more RFID chips to determine the structural health. The sensors and RFID chips may be passive and powered through the wireless communication from the remote reader. Such apparatuses and methods may be applied to any large structures requiring regular inspection, such as aircraft, ships, automobiles or buildings.

Abstract: An energy harvesting apparatus and method that is especially well suited for harvesting low frequency broadband vibration energy from a vibrating structure is presented. The apparatus includes a pair of disc springs that are arranged in an opposing relationship. A threaded fastening member and a threaded nut extend through apertures in each of the disc springs and enable a predetermined preload force to be applied to the disc springs. The preload effectively “softens” the disc springs, thus heightening the sensitivity of the disc springs to low frequency, low amplitude vibration energy. A piezoelectric material ring is secured to each of the disc springs. Each piezoelectric material ring experiences changes in strain as its associated disc spring deflects in response to vibration energy experienced from a vibrating structure.

Abstract: A sensor device for monitoring and testing for potential corrosion of structural elements is disclosed comprising a soluble material disposed adjacent to at least one conductor in a transmission line that reacts to the presence of moisture causing a detectable change in an electrical property of the conductor. The conductor may comprise a conductive ink that is disrupted when the soluble material dissolves beneath it. Alternately, the nonconductive soluble membrane may separate two conductors and moisture causes a disruption in the soluble membrane allowing the two conductors to short. Detected changes in the electrical properties of the one or more conductors can be used to indicate potential corrosion or structural imparement in the structural element. Connection to the sensor device may be through a connector or using a wireless reader which remotely energizes the sensor device comprising one or more RFID chips.

Abstract: A temperature sensor is described that includes a base, a first set of posts attached to the base having a first coefficient of thermal expansion, a second set of posts attached to the base and having a second coefficient of thermal expansion, and two substantially parallel conductive plates forming a capacitor. The first of the conductive plates is fixed to the first set of posts and the second of the conductive plates is fixed to the second set of posts. Temperature changes cause the first set of posts and the second set of posts to elongate at different rates, thereby changing a distance between the conductive plates and therefore the resulting capacitance. A system and method are also described for determining resonant frequency associated with the sensor which correlates to the temperature at the sensor when multiple sensors are networked across a system.

Abstract: Structural health monitoring apparatuses and methods are disclosed. One or more structural health sensors may be used to disconnect and/or connect one or more RFID chips to an antenna such that wireless communication with the one or more RFID chips (or the absence of wireless communication) through the antenna indicates the structural health status. Example structural health sensors may be moisture detecting or fracture detecting. A remote reader may be used to establish the wireless communication with the one or more RFID chips to determine the structural health. The sensors and RFID chips may be passive and powered through the wireless communication from the remote reader. Such apparatuses and methods may be applied to any large structures requiring regular inspection, such as aircraft, ships, automobiles or buildings.

Abstract: A broadband vibration energy harvesting apparatus and method. In one embodiment, a straight piezoelectric beam and a straight biasing beam are disposed parallel to one another and axially compressed by a support structure such that both of the beams are slightly bowed. This buckles and reduces the axial stiffness of both of the beams. The piezoelectric beam is secured to an external vibrating structure and supported by the structure. The flexing motion of the piezoelectric beam generates electrical signals that can be used to power a wide variety of devices. The apparatus is especially sensitive to small amplitude vibration signals and is able to harvest vibration energy over a wide range of frequencies, and is not limited to vibrations at discrete resonant frequencies. The apparatus is especially well suited for use in powering remotely located electrical sensors and actuators employed in automotive, aircraft and aerospace applications.

Abstract: An energy harvesting apparatus and method that is especially well suited for harvesting low frequency broadband vibration energy from a vibrating structure is presented. The apparatus includes a pair of disc springs that are arranged in an opposing relationship. A threaded fastening member and a threaded nut extend through apertures in each of the disc springs and enable a predetermined preload force to be applied to the disc springs. The preload effectively “softens” the disc springs, thus heightening the sensitivity of the disc springs to low frequency, low amplitude vibration energy. A piezoelectric material ring is secured to each of the disc springs. Each piezoelectric material ring experiences changes in strain as its associated disc spring deflects in response to vibration energy experienced from a vibrating structure.

Abstract: A broadband vibration energy harvesting apparatus and method. In one embodiment, a straight piezoelectric beam and a straight biasing beam are disposed parallel to one another and axially compressed by a support structure such that both of the beams are slightly bowed. This buckles and reduces the axial stiffness of both of the beams. The piezoelectric beam is secured to an external vibrating structure and supported by the structure. The flexing motion of the piezoelectric beam generates electrical signals that can be used to power a wide variety of devices. The apparatus is especially sensitive to small amplitude vibration signals and is able to harvest vibration energy over a wide range of frequencies, and is not limited to vibrations at discrete resonant frequencies. The apparatus is especially well suited for use in powering remotely located electrical sensors and actuators employed in automotive, aircraft and aerospace applications.