Integrated Strain and Piezoelectric Sensor System

Systems, devices, and methods for a dual-sensor apparatus (101), comprising: a conductive substrate (124); a piezoelectric material (126) disposed on the conductive substrate (124); and an electrically conductive trace (102) disposed on the piezoelectric material (126) in a strain gauge pattern, where the electrically conductive trace (102) comprises two leads; where the conductive substrate (124) and the electrically conductive trace (102) serve as electrodes for the piezoelectric material (126) to form a piezoelectric sensor; and where the electrically conductive trace (102) serves as a strain sensor.

FIELD OF ENDEAVOR

The invention relates generally to structural health monitoring and damage detection, and more particularly to sensors using piezoelectric material integrated with electrically conductive material.

BACKGROUND

Structures as well as electronic and electromechanical systems, such as automotive vehicles and aircrafts, are often subjected to vibration and shock, which tend to shorten the life of these systems and make them susceptible to intermittent and catastrophic failure. Methods of measuring an integrity of a structure include non-destructive evaluation techniques, such as ultrasonics, infrared, and X-ray imaging. Techniques such as these can be costly, time consuming, and often only provide an understanding of a structure's health at finite intervals or times. For example, if one wanted to conduct a measure of a structures health using an X-ray imaging device, a process may include disassembling or disconnecting a structure from a system, relocating the structure to a location where an X-ray machine resides, setting and X-ray machine up for imaging of a desired location on the structure, and executing an imaging process. This process may further comprise removing the structure from the X-ray machine, relocating it back to its original location, and reassembling and/or connecting the structure to a system. A process such as this would be time-consuming, labor intensive, and may incur costs of a system being down while conducting the structural inspection. Such non-destructive evaluation methods cannot be used for continuous monitoring for timely damage detection.

SUMMARY

In one embodiment, a dual-sensor apparatus may include: a conductive substrate; a piezoelectric material disposed on the conductive substrate; and an electrically conductive trace disposed on the piezoelectric material in a strain gauge pattern, where the electrically conductive trace comprises two leads; where the conductive substrate and the electrically conductive trace serve as electrodes for the piezoelectric material to form a piezoelectric sensor; and where the electrically conductive trace serves as a strain sensor.

In additional dual-sensor apparatus embodiments, the dual-sensor apparatus may be attached to a structural surface for structural damage detection and health monitoring. Additional dual-sensor apparatus embodiments may further include: a conductive trance sensor amplifier; an electrically conductive trace current loop formed between the electrically conductive trace and the conductive trance sensor amplifier through the two leads of the electrically conductive trace; a charge amplifier; a piezoelectric current loop formed between the sensor apparatus and a sensor amplifier through two connections between the electrically conductive trace and the electrically conductive trace sensor amplifier, and between the conductive substrate and the charge amplifier; where the piezoelectric current loop, the connection between the conductive substrate and the charge amplifier may be connected to a ground, where the conductive trance sensor amplifier may be configured to measure a strain on a surface connected to the conductive substrate using the electrically conductive trace current loop generated by a resistance change of the electrically conductive trace; and where the charge amplifier may be configured to measure an impact shock on a surface connected to the conductive substrate using the piezoelectric current loop generated by the piezoelectric material.

Additional dual-sensor apparatus embodiments may further include: a high input impedance buffer connected to the conductive trance sensor amplifier; a high input impedance buffer connected to the piezoelectric sensor amplifier; where the high input impedance buffer may be configured to isolate an output of the conductive trance sensor amplifier to prevent a current flow to the ground; and where the high input impedance buffer may be configured to isolate an output of the piezoelectric sensor amplifier to prevent the current flow to the ground. In additional dual-sensor apparatus embodiments, said conductive substrate may be the surface of the structure to be monitored.

A segmented dual-sensor apparatus embodiment may include: a conductive substrate; a piezoelectric material disposed on the conductive substrate; and a plurality of electrically conductive traces disposed on portions of the piezoelectric material in respective strain gauge patterns, where each electrically conductive trace comprises two leads, where the conductive substrate and the plurality of electrically conductive traces serve as electrodes for the piezoelectric material to form a plurality of piezoelectric sensors; and where the plurality of electrically conductive traces serve as a plurality of strain sensors.

In additional segmented dual-sensor apparatus embodiments, the segmented dual-sensor apparatus may be attached to a structural surface for structural damage detection, damage location identification, and structural health monitoring.

Additional segmented dual-sensor apparatus embodiments may further include: a plurality of conductive trance sensor amplifiers; a plurality of electrically conductive trace current loops formed between the sensor apparatus and a respective sensor amplifier of the plurality of sensor amplifiers through the respective two leads of each electrically conductive trace; a plurality of piezoelectric current loops formed between the sensor apparatus and a respective sensor amplifier of the plurality of sensor amplifiers through the respective two leads of each electrically conductive trace and the conductive substrate; where the plurality of the piezoelectric current loops, the connection between the conductive substrate and a respective sensor amplifier of the plurality of sensor amplifiers may be connected to a ground; where the plurality of sensor amplifiers may be configured to measure a strain on portions of a surface connected to the conductive substrate using a respective conductive current loop of the plurality of the electrically conductive trace current loops; and where the plurality of sensor amplifiers may be configured to measure an impact shock on portions of a surface connected to the conductive substrate using a respective piezoelectric current loop of the plurality of the piezoelectric current loops.

Additional segmented dual-sensor apparatus embodiments may further include: a plurality of output buffers connected to a respective sensor amplifier of the plurality of sensor amplifiers; and where the plurality of output buffers may be configured to isolate a plurality of outputs of the sensor amplifiers to prevent the current flow to the ground. In additional segmented dual-sensor apparatus embodiments, said conductive substrate may be the surface of the structure to be monitored.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating the general principles of the embodiments discloses herein and is not meant to limit the concepts disclosed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations. Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the description as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc.

The present system allows for the measurement of an impact force on a structure or structures, structural surface strains, as well as the detection of structural damage using simultaneous measurement by the integrated piezoelectric sensors and electrically conductive trace sensors, to allow a singular system to provide accurate, continuous, granular, and reliable monitoring results. The disclosed dual-sensor system provides a cost and time effective method for continuous monitoring and assessing structural health and timely detection of structural damage to ensure structural integrity. Having the ability to monitor structural health is advantageous to a user and/or owner of a structure because it provides real-time insight into the integrity, safety, and potential failure of the structure.

The present system includes two integrated sensors: (1) A piezoelectric sensor that measures impact forces applied to the piezoelectric material by measuring the electrical charges generated by the piezoelectric material in response to the impact forces. The piezoelectric sensor can also detect, in real time, initiation of structural damage such as cracking and composite fiber breakage, because such damage events generate mechanical stress and electrical charges in the piezoelectric material. (2) A strain sensor using the electrically conductive trace (that also serve as the electrodes of the piezoelectric sensor) that measures structural strain. The electrical resistance of the trace increases as the structural strain increases. Therefore, by measuring the resistance, the structural strain is monitored. Excessive strain is an indication of structural damage. It is possible to set up a resistance threshold for damage early warning.

Methods of structural health monitoring in prior art include the use of electric conductivity of a structural material (such as carbon fibers). These methods measure an electrical resistance across a material in relation to a change in a strain, but they may be difficult to implement due to difficulties in insulating electrical currents in a sensor material. Furthermore, methods such as these may not be effective in detecting dynamic impact loads and structural damage initiation due to sensitivity of a measured change in electrical resistance. By simultaneously measuring both dynamic signals such as the impact force and structural damage initiation and static signals such as structural strain, the disclosed dual-sensor system provides high sensitivity, redundancy, and reliability in real-time detection of impact force and structural damage

FIG.1Adepicts a high-level block diagram of a dual-sensor apparatus101, according to one embodiment. The dual-sensor apparatus101includes an electrically conductive trace102(e.g., metal foil, metal wire, conductive paint) on a surface of the piezoelectric material126, opposite the surface shared with a conductive substrate124, the electrically conductive trace102and the conductive substrate124may be utilized as the electrodes to create a piezoelectric sensor, while the electrically conductive trace102can be used to create a strain sensor. The integrated sensor can be affixed to the surface of a structure to monitor the structural surface strain, impact loads on the structure, and damage initiation in the structure.

FIG.1Bdepicts a high-level block diagram of a simultaneous electrically conductive trace and piezoelectric sensor amplifier circuit for a single element system100, according to one embodiment. Stresses, such as shock and vibration, can affect a wide variety of structures including electronics as well as components making up air-worthy equipment and parts. Some environments such as in aerial flight, see continual stresses imposed on them from turbulence or other phases of flight, such as takeoff and landing. An airplane's wing for example, must absorb millions of instances of flex and shock over the course of service. Other more sensitive components within an airplane, such as electronics, must also endure a similar number of instances of shock and vibration. Being able to understand the health of a wing is critical in determining an airplanes airworthiness as well as to plan maintenance and/or predict failure. Similarly, electronic pieces of equipment which are sensitive to shock require regular testing to ensure the functionality of the equipment. The ability to test and measure the integrity of a critical piece of equipment is invaluable. As there are multiple methods of measuring the integrity of a structures health it would be beneficial to i) use multiple methods during a testing period to ensure an accurate understanding of a structures health, and ii) collect a multitude of continuous structural health data points to have an up-to-date measure of the condition of a structure's health. The disclosed system100provides the ability to simultaneously measure a structures integrity using multiple methods of measurement, including an electrically conductive trace current loop128and a piezoelectric current loop146, as well as provide continuous data points of those measurements.

In an embodiment depicted inFIG.1B, a conductive substrate124surface (e.g., metal, carbon fiber, CFRP), shares a surface with a piezoelectric material126(e.g., PVDF, PZT, and quarts). By creating a strain gauge pattern in the dual-sensor apparatus101using an electrically conductive trace102(e.g., metal foil, metal wire, conductive paint) on a surface of the piezoelectric material126, opposite the surface shared with a conductive substrate124, the electrically conductive trace102and the conductive substrate124may be utilized as the electrodes to create a piezoelectric sensor, while the electrically conductive trace102can be used to create a strain sensor. The integrated sensor can be affixed to the surface of a structure to monitor the structural surface strain, impact loads on the structure, and damage initiation in the structure.

In this embodiment the structural surface is electrically conductive allowing for an electrical current to create a piezoelectric current loop146between the two leads of the electrically conductive trace102and the conductive substrate124. In other embodiments where a structural surface is of a non-conductive material, a conductive substrate is added between the piezoelectric material126and a structural surface to create the piezoelectric current loop146. This configuration creates two loops, an electrically conductive trace current loop128between the two leads of the electrically conductive trace102and two inputs of a conductive trance sensor amplifier104, and the piezoelectric current loop146comprising a ground122grounding the conductive substrate124, a lead extending from the ground122to an input of a charge amplifier136, and one of two leads extending from the electrically conductive trace102entering a Wheatstone bridge130of the electrically conductive trace sensor amplifier104. The two loops may be used as circuits to measure strain (by the electrically conductive trace current loop128) and impact shock (by the piezoelectric current loop146).

Signals leading from the loops146,128may be received by sensor amplifier144, where the sensor amplifiers comprise of an electrically conductive trace sensor amplifier104, a piezoelectric sensor amplifier118, and a power supply134. Leads creating the electrically conductive trace current loop128, or the strain signal, may be amplified by first entering the Wheatstone bridge130of the electrically conductive trace sensor amplifier104. The strain signal may then continue to a differential amplifier132prior to exiting the sensor amplifier144. The impact shock signal created using the piezoelectric current loop146may be amplified by sensor amplifier144by first entering a piezoelectric sensor amplifier118which comprises a charge amplifier136. The shock impact signal may then exit the sensor amplifier144as outputs. To combine the two amplified signals (the strain signal and the shock signal), the sensor amplifier144outputs are isolated148using high input impedance buffers or output buffers116. A power supply powering the sensor amplifier144may also be isolated148using an isolated power supply140. This isolated design embodiment only allows the current generated by the piezoelectric charge, measurable in the piezoelectric current loop146, to go through the charge amplifier136. This embodiment allows the charge amplifier136to accurately convert the piezoelectric charge, of piezoelectric current loop146, to a voltage without being affected by the electrically conductive trace sensor amplifier104and the receiver of the outputs such as a data acquisition (DAQ) device (not depicted). The isolated strain signal may enter a high-z buffer138prior to being received by a DAQ as a trance sensor output108. Similarly, the isolated shock signal, upon exiting the piezoelectric sensor amplifier118of the sensor amplifier144may enter a high-Z buffer142and subsequently be received by a DAQ as a piezo sensor output114. The DAQ may use output current loops110created by the piezo sensor output114, the trace sensor output108, and a ground112of a power supply140.

A dual-sensor apparatus101may include: a conductive substrate124; a piezoelectric material126disposed on the conductive substrate124; and an electrically conductive trace102disposed on the piezoelectric material126in a strain gauge pattern, where the electrically conductive trace102comprises two leads; where the conductive substrate124and the electrically conductive trace102serve as electrodes for the piezoelectric material126to form a piezoelectric sensor; and where the electrically conductive trace102serves as a strain sensor.

In additional dual-sensor apparatus101embodiments, the dual-sensor apparatus101may be attached to a structural surface for structural damage detection and health monitoring. Additional dual-sensor apparatus101embodiments may further include: a conductive trance sensor amplifier104; an electrically conductive trace current loop128formed between the electrically conductive trace102and the conductive trance sensor amplifier104through the two leads of the electrically conductive trace102; a charge amplifier136; a piezoelectric current loop146formed between the sensor apparatus101and a sensor amplifier144through two connections between the electrically conductive trace102and the electrically conductive trace sensor amplifier104, and between the conductive substrate124and the charge amplifier136; where the piezoelectric current loop146, the connection between the conductive substrate124and the charge amplifier136may be connected to a ground122, where the conductive trance sensor amplifier104may be configured to measure a strain on a surface connected to the conductive substrate124using the electrically conductive trace current loop128generated by a resistance change of the electrically conductive trace102; and where the charge amplifier136may be configured to measure an impact shock on a surface connected to the conductive substrate124using the piezoelectric current loop146generated by the piezoelectric material126.

Additional dual-sensor apparatus101embodiments may further include: a high input impedance buffer138connected to the conductive trance sensor amplifier104; a high input impedance buffer142connected to the piezoelectric sensor amplifier104; where the high input impedance buffer138may be configured to isolate an output of the conductive trance sensor amplifier104to prevent a current flow120to the ground122; and where the high input impedance buffer142may be configured to isolate an output of the piezoelectric sensor amplifier118to prevent the current flow120to the ground122. In additional dual-sensor apparatus101embodiments, said conductive substrate124may be the surface of the structure to be monitored.

FIG.2depicts a high-level block diagram of a simultaneous electrically conductive trace and piezoelectric sensor amplifier circuit for a multiple element system200, according to one embodiment. The system200may be used in situations where multiple locations of a structure require simultaneous and continuous shock and strain measuring. The system200depicts an embodiment where this measurement requirement is fulfilled comprising a plurality of electrically conductive traces202,204which illustrate a system where the plurality of electrically conductive traces202,204are located at different locations on a structure. Similar to the embodiment depicted inFIG.1B, the electrically conductive traces202,204reside substantially on a surface of a piezoelectric material234creating a strain gauge pattern opposite a surface of the piezoelectric material234which may abut a conductive substrate232.

In other embodiments where a structural surface (not depicted) is of a non-conductive material, a conductive substrate232may be added between the piezoelectric material234and the structural surface to create the piezoelectric current loop236for electrically conductive trace1202, and a second piezo electric current loop (237) for electrically conductive trace2204.

By using strain gauge patterns created by electrically conductive traces202,204on a surface of the piezoelectric material234, electrically conductive trace current loops230and238create a signal capable of measuring a strain within a conductive substrate232. A piezoelectric current loop236created between a lead208extending from a ground206from conductive substrate232, and leads extending from electrically conductive trace1202and/or electrically conductive trace2204may be used to create a shock sensor. The integrated sensor can be affixed to the surface of a structure to monitor the structural surface strain, impact loads on the structure, and damage initiation in the structure.

In this embodiment the structural surface is electrically conductive allowing for an electrical current to create piezoelectric current loops230,238between the leads of electrically conductive traces202and204and the conductive substrate232. In other embodiments where a structural surface is of a non-conductive material, a conductive substrate is added between the piezoelectric material234and the structural surface to create piezoelectric current loops236(and a second loop not depicted). This configuration creates multiple loops comprising: electrically conductive trace current loops230,238between the two leads of the electrically conductive traces202,204and two inputs of conductive trance sensor amplifiers226,228; and piezoelectric current loops236(and a second loop not depicted) comprising a ground206grounding a conductive substrate232, a lead extending from the ground208to an input of the electrically conductive trace sensor amplifier1226and electrically conductive trace sensor amplifier2228, and one of two leads extending from electrically conductive traces202,204entering the electrically conductive trace sensor amplifier1226and electrically conductive trace sensor amplifier2228. The loops230,238,236may be used as circuits to measure strain consecutively.

Signals created by the loops230,238,236may be received by electrically conductive trace sensor amplifier1226and electrically conductive trace sensor amplifier2(228, where the electrically conductive trace sensor amplifier1226and electrically conductive trace sensor amplifier2228comprise components described inFIG.1B. Similar to that which is described inFIG.1B, those signals leading from electrically conductive trace1202and electrically conductive trace2204are amplified in electrically conductive trace sensor amplifier1202and electrically conductive trace sensor amplifier2204, isolated212, enter output buffer1224and output buffer2214, and exit the system200as trace sensor output1222, trace sensor output2218, and piezo sensor output1220and piezo sensor output2216. A DAQ (not depicted) can then receive these signals for further analysis and recording. In some embodiments, a single piezoelectric layer may be used in combination with multiple conductive substrates.

In some embodiments, piezoelectric material may be used as resin matrix for composite materials. In some embodiments, various patterns may be dependent on the structure surface contour. In some embodiments, the strain gauge pattern may be optimized for the surface contour. One example embodiment may include a composite vehicle bumper beam made of a carbon fiber shell. The use of multiple traces may allow for more accurate identification of a damage location. In some embodiments, an average strain signal may be obtained by using one large single trace. One embodiment may include analog to digital signal converters where threshold values are used for digital signal values where each value has a significance such as, e.g., “low”, “moderate”, “high/critical”. In one embodiment, analog strain and shock value ranges may be used where output values represent ranges concerning a strain or impact force value.

A segmented dual-sensor apparatus201may include: a conductive substrate232; a piezoelectric material234disposed on the conductive substrate232; and a plurality of electrically conductive traces202,204disposed on portions of the piezoelectric material234in respective strain gauge patterns, where each electrically conductive trace202,204comprises two leads, where the conductive substrate232and the plurality of electrically conductive traces202,204serve as electrodes for the piezoelectric material234to form a plurality of piezoelectric sensors; and where the plurality of electrically conductive traces202,204serve as a plurality of strain sensors.

In additional segmented dual-sensor apparatus201embodiments, the segmented dual-sensor apparatus201may be attached to a structural surface for structural damage detection, damage location identification, and structural health monitoring. Additional segmented dual-sensor apparatus201embodiments may further include: a plurality of conductive trance sensor amplifiers226,228; a plurality of electrically conductive trace current loops230,238formed between the sensor apparatus201and a respective sensor amplifier of the plurality of sensor amplifiers226,228through the respective two leads of each electrically conductive trace202,204; a plurality of piezoelectric current loops236,237formed between the sensor apparatus201and a respective sensor amplifier226,228of the plurality of sensor amplifiers226,228through the respective two leads of each electrically conductive trace202,204and the conductive substrate232; where the plurality of the piezoelectric current loops236,237, the connection between the conductive substrate232and a respective sensor amplifier226,228of the plurality of sensor amplifiers226,228may be connected to a ground206; where the plurality of sensor amplifiers226,228may be configured to measure a strain on portions of a surface connected to the conductive substrate232using a respective conductive current loop230,238of the plurality of the electrically conductive trace current loops230,238; and where the plurality of sensor amplifiers226,228may be configured to measure an impact shock on portions of a surface connected to the conductive substrate232using a respective piezoelectric current loop236,237of the plurality of the piezoelectric current loops236,237.

Additional segmented dual-sensor apparatus201embodiments may further include: a plurality of output buffers224,214connected to a respective sensor amplifier226,228of the plurality of sensor amplifiers226,228; and where the plurality of output buffers224,214may be configured to isolate a plurality of outputs of the sensor amplifiers224,214to prevent the current flow205to the ground206. In additional segmented dual-sensor apparatus201embodiments, said conductive substrate232may be the surface of the structure to be monitored.

FIG.3depicts a schematic of a sensor amplifier circuit for a single element system300, according to one embodiment. System300may comprise: a Wheatstone bridge302, where the Wheatstone bridge comprises: a resisters R1340, R2328, and R3330; and resisters R4322, R5324, and U3326which provide power to the Wheatstone bridge302. System300may further comprise: a differential amplifier304, where the differential amplifier304comprises an instrumentation amplifier U1332; a charge amplifier316, where the charge amplifier316comprises: an operational amplifier U2338, a resister R7334, and a capacitor C1336; high-Z buffers308,314, where the high-Z buffers comprise high impedance amplifiers U4340, U5342consecutively; a power supply for sensor amplifiers DC1306, where the power supply for sensor amplifiers DC1306isolates the power supply to the sensor amplifier circuit300; a trace sensor output310; and a piezo sensor output312.

FIG.4depicts a schematic of a sensor amplifier circuit for multiple elements system400, according to one embodiment. System400may use similar circuitry depicted inFIG.3where according to the embodiment multiple electrically conductive traces1,3(422,418) enter sensor amplifiers1420, and2414. Circuitry which comprise sensor amplifiers1and2(420,414) may be significantly identical to each other and the circuitry described inFIG.3's sensor amplifier system300, where sensor amplifiers1420, and2414also comprise output buffers1402, and2408consecutively as well as at least two outputs, where the at least two sensor outputs comprise a trace sensor output1404and a piezo sensor output1406, for the sensor amplifier1420and corresponding at least two outputs for sensor amplifier2414, where the at least two sensor outputs comprise a trace sensor output2410and a piezo sensor output2412. The sensor amplifier circuit may also receive an input from the conductive substrate416.

FIG.5depicts a high-level flowchart of a method500of receiving and amplifying a strain signal comprising one of two simultaneous electrically conductive trace and piezoelectric sensor amplifier circuit signals, according to one embodiment. The method500may comprise receiving a strain signal from an electrically conductive trace (step502). The method500may then comprise Amplifying the received strain signal using an electrically conductive trace amplifier wherein the electrically conductive trace amplifier passes the strain signal through a Wheatstone bridge and subsequently through a differential amplifier (step504). The method500may further comprise isolating the power supply of the electrically conductive trace amplifier using an isolated DC-DC converter (step506). The method500may additionally comprise isolating the output of the electrically conductive trace amplifier using a high-z buffer (step508). The method may lastly comprise outputting a trace sensor output to a data acquisition device (step510).

FIG.6depicts a high-level flowchart of a method500of receiving and amplifying a shock signal comprising one of two simultaneous electrically conductive trace and piezoelectric sensor amplifier circuit signals, according to one embodiment. The method600may comprise receiving a shock signal from a piezoelectric sensor (step602). The method600may then comprise Amplifying the received shock signal using a piezoelectric sensor amplifier wherein the using a charge amplifier (step604). The method600may further comprise isolating the power supply of the piezoelectric sensor amplifier using an isolated DC-DC converter (step606). The method600may additionally comprise isolating the output of the piezoelectric sensor amplifier using a high-z buffer (step608). The method may lastly comprise outputting a piezo sensor output to a data acquisition device (step610).

FIG.7depicts a high-level block diagram of a simultaneous electrically conductive trace and piezoelectric sensor amplifier circuit for a single element system700, according to one embodiment. The system700may comprise: a measurement area702, where the measurement area702comprises: an electrically conductive trace726, a piezoelectric material728, and a conductive substrate722; an electrically conductive trace sensor amplifier704, where the electrically conductive trace sensor amplifier704comprises a Wheatstone bridge714and a differential amplifier724; a power supply716; a piezoelectric sensor amplifier718, where the piezoelectric sensor amplifier718comprises a charge amplifier720; and output buffers706, where the output buffers706comprise: high-z buffers708and712, and a power supply710.

FIG.8Adepicts a perspective view of a sensor system800integrated into a composite vehicle bumper beam made of a carbon fiber shell, according to one embodiment.

FIG.8Bdepicts a cross-sectional view of the sensor system800ofFIG.8Aalong line A-A. The sensor system800may include a carbon fiber shell802. The carbon fiber shell802may surround a core such as a natural fiber composite core804. At least a portion of an outer surface of the carbon fiber shell802may include a piezoelectric layer806. An electrically conductive trace808may be disposed on the piezoelectric layer806.

FIG.9is a high-level block diagram900showing a computing system comprising a computer system useful for implementing an embodiment of the system and process, disclosed herein. Embodiments of the system may be implemented in different computing environments. The computer system includes one or more processors902, and can further include an electronic display device904(e.g., for displaying graphics, text, and other data), a main memory906(e.g., random access memory (RAM)), storage device908, a removable storage device910(e.g., removable storage drive, a removable memory module, a magnetic tape drive, an optical disk drive, a computer readable medium having stored therein computer software and/or data), user interface device911(e.g., keyboard, touch screen, keypad, pointing device), and a communication interface912(e.g., modem, a network interface (such as an Ethernet card), a communications port, or a PCMCIA slot and card). The communication interface912allows software and data to be transferred between the computer system and external devices. The system further includes a communications infrastructure914(e.g., a communications bus, cross-over bar, or network) to which the aforementioned devices/modules are connected as shown.

Information transferred via communications interface914may be in the form of signals such as electronic, electromagnetic, optical, or other signals capable of being received by communications interface914, via a communication link916that carries signals and may be implemented using wire or cable, fiber optics, a phone line, a cellular/mobile phone link, an radio frequency (RF) link, and/or other communication channels. Computer program instructions representing the block diagram and/or flowcharts herein may be loaded onto a computer, programmable data processing apparatus, or processing devices to cause a series of operations performed thereon to produce a computer implemented process.

Embodiments have been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments. Each block of such illustrations/diagrams, or combinations thereof, can be implemented by computer program instructions. The computer program instructions when provided to a processor produce a machine, such that the instructions, which execute via the processor, create means for implementing the functions/operations specified in the flowchart and/or block diagram. Each block in the flowchart/block diagrams may represent a hardware and/or software module or logic, implementing embodiments. In alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures, concurrently, etc.

Computer programs (i.e., computer control logic) are stored in main memory and/or secondary memory. Computer programs may also be received via a communications interface912. Such computer programs, when executed, enable the computer system to perform the features of the embodiments as discussed herein. In particular, the computer programs, when executed, enable the processor and/or multi-core processor to perform the features of the computer system. Such computer programs represent controllers of the computer system.

FIG.10shows a block diagram of an example system1000in which an embodiment may be implemented. The system1000includes one or more client devices1001such as consumer electronics devices, connected to one or more server computing systems1030. A server1030includes a bus1002or other communication mechanism for communicating information, and a processor (CPU)1004coupled with the bus1002for processing information. The server1030also includes a main memory1006, such as a random-access memory (RAM) or other dynamic storage device, coupled to the bus1002for storing information and instructions to be executed by the processor1004. The main memory1006also may be used for storing temporary variables or other intermediate information during execution or instructions to be executed by the processor1004. The server computer system1030further includes a read only memory (ROM)1008or other static storage device coupled to the bus1002for storing static information and instructions for the processor1004. A storage device1010, such as a magnetic disk or optical disk, is provided and coupled to the bus1002for storing information and instructions. The bus1002may contain, for example, thirty-two address lines for addressing video memory or main memory1006. The bus1002can also include, for example, a 32-bit data bus for transferring data between and among the components, such as the CPU1004, the main memory1006, video memory and the storage1010. Alternatively, multiplex data/address lines may be used instead of separate data and address lines.

The server1030may be coupled via the bus1002to a display1012for displaying information to a computer user. An input device1014, including alphanumeric and other keys, is coupled to the bus1002for communicating information and command selections to the processor1004. Another type or user input device comprises cursor control1016, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to the processor1004and for controlling cursor movement on the display1012.

According to one embodiment, the functions are performed by the processor1004executing one or more sequences of one or more instructions contained in the main memory1006. Such instructions may be read into the main memory1006from another computer-readable medium, such as the storage device1010. Execution of the sequences of instructions contained in the main memory1006causes the processor1004to perform the process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in the main memory1006. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the embodiments. Thus, embodiments are not limited to any specific combination of hardware circuitry and software.

The terms “computer program medium,” “computer usable medium,” “computer readable medium”, and “computer program product,” are used to generally refer to media such as main memory, secondary memory, removable storage drive, a hard disk installed in hard disk drive, and signals. These computer program products are means for providing software to the computer system. The computer readable medium allows the computer system to read data, instructions, messages or message packets, and other computer readable information from the computer readable medium. The computer readable medium, for example, may include non-volatile memory, such as a floppy disk, ROM, flash memory, disk drive memory, a CD-ROM, and other permanent storage. It is useful, for example, for transporting information, such as data and computer instructions, between computer systems. Furthermore, the computer readable medium may comprise computer readable information in a transitory state medium such as a network link and/or a network interface, including a wired network or a wireless network that allow a computer to read such computer readable information. Computer programs (also called computer control logic) are stored in main memory and/or secondary memory. Computer programs may also be received via a communications interface. Such computer programs, when executed, enable the computer system to perform the features of the embodiments as discussed herein. In particular, the computer programs, when executed, enable the processor multi-core processor to perform the features of the computer system. Accordingly, such computer programs represent controllers of the computer system.

Generally, the term “computer-readable medium” as used herein refers to any medium that participated in providing instructions to the processor1004for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as the storage device1010. Volatile media includes dynamic memory, such as the main memory1006. Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise the bus1002. Transmission media can also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications.

Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to the processor1004for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to the server1030can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal. An infrared detector coupled to the bus1002can receive the data carried in the infrared signal and place the data on the bus1002. The bus1002carries the data to the main memory1006, from which the processor1004retrieves and executes the instructions. The instructions received from the main memory1006may optionally be stored on the storage device1010either before or after execution by the processor1004.

The server1030also includes a communication interface1018coupled to the bus1002. The communication interface1018provides a two-way data communication coupling to a network link1020that is connected to the worldwide packet data communication network now commonly referred to as the Internet1028. The Internet1028uses electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on the network link1020and through the communication interface1018, which carry the digital data to and from the server1030, are exemplary forms or carrier waves transporting the information.

In another embodiment of the server1030, interface1018is connected to a network1022via a communication link1020. For example, the communication interface1018may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line, which can comprise part of the network link1020. As another example, the communication interface1018may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, the communication interface1018sends and receives electrical electromagnetic or optical signals that carry digital data streams representing various types of information.

The network link1020typically provides data communication through one or more networks to other data devices. For example, the network link1020may provide a connection through the local network1022to a host computer1024or to data equipment operated by an Internet Service Provider (ISP). The ISP in turn provides data communication services through the Internet1028. The local network1022and the Internet1028both use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on the network link1020and through the communication interface1018, which carry the digital data to and from the server1030, are exemplary forms or carrier waves transporting the information.

The server1030can send/receive messages and data, including e-mail, program code, through the network, the network link1020and the communication interface1018. Further, the communication interface1018can comprise a USB/Tuner and the network link1020may be an antenna or cable for connecting the server1030to a cable provider, satellite provider or other terrestrial transmission system for receiving messages, data and program code from another source.

The example versions of the embodiments described herein may be implemented as logical operations in a distributed processing system such as the system1000including the servers1030. The logical operations of the embodiments may be implemented as a sequence of steps executing in the server1030, and as interconnected machine modules within the system1000. The implementation is a matter of choice and can depend on performance of the system1000implementing the embodiments. As such, the logical operations constituting said example versions of the embodiments are referred to for e.g., as operations, steps or modules.

Similar to a server1030described above, a client device1001can include a processor, memory, storage device, display, input device and communication interface (e.g., e-mail interface) for connecting the client device to the Internet1028, the ISP, or LAN1022, for communication with the servers1030.

The system1000can further include computers (e.g., personal computers, computing nodes)1005operating in the same manner as client devices1001, wherein a user can utilize one or more computers1005to manage data in the server1030.