Abstract: Described herein is an apparatus for detecting damage in a structure that includes a plurality of first piezoelectric sensing elements arranged in a generally circular shape. The apparatus also includes an annular-shaped second piezoelectric sensing element positioned adjacent the plurality of first piezoelectric sensing elements. One of the plurality of first piezoelectric sensing elements or the annular-shaped second piezoelectric sensing element generates a wave through the structure and other of the plurality of first piezoelectric sensing elements or the annular-shaped second piezoelectric sensing element senses the wave after passing through the structure.

Abstract: Described herein is an apparatus for detecting damage in a structure that includes a plurality of first piezoelectric sensing elements arranged in a generally circular shape. The apparatus also includes an annular-shaped second piezoelectric sensing element positioned adjacent the plurality of first piezoelectric sensing elements. One of the plurality of first piezoelectric sensing elements or the annular-shaped second piezoelectric sensing element generates a wave through the structure and other of the plurality of first piezoelectric sensing elements or the annular-shaped second piezoelectric sensing element senses the wave after passing through the structure.

Abstract: A method for identifying Lamb wave modes and structural health monitoring may include transmitting a Lamb wave through a structure for monitoring the structural health of the structure. The method may also include measuring an instantaneous thickness of the structure at a predetermined location of the structure during passage of the Lamb wave at the predetermined location. The method may additionally include identifying a mode of the Lamb wave from the instantaneous thickness of the structure.

Abstract: A method for monitoring and diagnosing the health of a structure. The method includes providing a plurality of damage monitoring units each having at least one actuator, at least one sensor and a data collection device. The sensors are arranged and disposed to measure vibration produced by the actuator and provide a signal corresponding to the measured vibration to the data collection device. The actuator is activated and the vibration is measured with the sensor. The signal is compared to a reference signal and a damage index value is determined in response to the comparison between the signal and reference signal. The damage index value is transmitted for each vibratory path to a central processing device and the damage index values are analyzed for the plurality of damage monitoring units to determine the location of damage to the structure.

Abstract: Methods and systems are provided for obtaining structural health data for evaluating a structural health of a component. A transducer detects a first signal representative of a signal transmitted through at least a portion of the component. An estimated signal for a remote transducer is determined based on at least the first signal and a transfer function.

Abstract: A method of controlling mixing of a flow exiting a downstream end of a primary nozzle associated with a jet engine. The method may involve coupling a shape memory alloy (SMA) element to a mixing structure disposed at the downstream edge of the primary nozzle. An electrical signal may be applied to the SMA element to heat the SMA element and induce a phase change in the SMA element. The phase change may cause an axial length of the SMA element to constrict, to cause movement of the mixing structure into a path of the flow exiting the primary nozzle.

Abstract: Systems and methods are provided for detecting an anomaly in a hidden portion of a first layer of a multi-layer structure. A monitoring element is provided on at least one exposed end of a fastener that extends through the multi-layer structure, and another monitoring element on an exposed portion of the first layer. With at least one of the monitoring elements, an inspection signal is introduced into the multi-layer structure including the hidden portion of the first layer. The inspection signal is then sensed with at least another one of the monitoring elements following propagation of the inspection signal through at least a portion of the multi-layer structure including the hidden portion of the first layer. Finally, an anomaly may be detected in the hidden portion of the first layer based upon the inspection signal that has been sensed.

Abstract: A method and apparatus for an airfoil, a flexible skin, and a shape control system. The flexible skin forms a control surface of the airfoil. The shape control system is capable of changing a shape of the control surface formed by the flexible skin between a plurality of shapes, wherein a gap does not occur during a changing of the shape of the control surface.

Abstract: A method of controlling mixing of a flow exiting a downstream end of a primary nozzle associated with a jet engine. The method may involve coupling a shape memory alloy (SMA) element to a mixing structure disposed at the downstream edge of the primary nozzle. An electrical signal may be applied to the SMA element to heat the SMA element and induce a phase change in the SMA element. The phase change may cause an axial length of the SMA element to constrict, to cause movement of the mixing structure into a path of the flow exiting the primary nozzle.

Abstract: A method of controlling mixing of a flow exiting a nozzle associated with a jet engine. The method may involve pivotally supporting a mixing structure forming a hinge device at a downstream edge of the nozzle. A shape memory alloy (SMA) element may be used to couple to the mixing structure. Heat may be generated by a flow exiting the nozzle to induce a phase change in the SMA element. The phase change may cause an axial length of the SMA element to constrict, to cause a pivoting movement of the mixing structure into a path of the flow exiting the nozzle.

Abstract: Methods and systems are provided for obtaining structural health data for evaluating a structural health of a component. A transducer detects a first signal representative of a signal transmitted through at least a portion of the component. An estimated signal for a remote transducer is determined based on at least the first signal and a transfer function.

Abstract: A method for determining the health of a structural element. The method includes providing a plurality of transducer elements arranged and disposed to permit measurement of vibration generated by at least one of the transducer elements at one or more of the other transducers elements. Vibration is induced with at least one transducer element. Vibration is measured at least one other transducer element, where the measured vibration corresponding to a vibratory path. At least one damage index value is calculated for each vibratory path in response to the measured vibration. At least one damage image is generated in response to the damage index value. The damage image assigns damage index values to each vibratory path. A damage location is determined from the damage image.

Abstract: Systems and methods are provided for detecting an anomaly in a hidden portion of a first layer of a multi-layer structure. A monitoring element is provided on at least one exposed end of a fastener that extends through the multi-layer structure, and another monitoring element on an exposed portion of the first layer. With at least one of the monitoring elements, an inspection signal is introduced into the multi-layer structure including the hidden portion of the first layer. The inspection signal is then sensed with at least another one of the monitoring elements following propagation of the inspection signal through at least a portion of the multi-layer structure including the hidden portion of the first layer. Finally, an anomaly may be detected in the hidden portion of the first layer based upon the inspection signal that has been sensed.

Abstract: A method and apparatus for an airfoil, a flexible skin, and a shape control system. The flexible skin forms a control surface of the airfoil. The shape control system is capable of changing a shape of the control surface formed by the flexible skin between a plurality of shapes, wherein a gap does not occur during a changing of the shape of the control surface.

Abstract: A method of controlling mixing of a flow exiting a nozzle associated with a jet engine. The method may involve pivotally supporting a mixing structure forming a hinge device at a downstream edge of the nozzle. A shape memory alloy (SMA) element may be used to couple to the mixing structure. Heat may be generated by a flow exiting the nozzle to induce a phase change in the SMA element. The phase change may cause an axial length of the SMA element to constrict, to cause a pivoting movement of the mixing structure into a path of the flow exiting the nozzle.

Abstract: A method for altering the shape of an exhaust mixing structure extending from a downstream end of a jet engine nacelle nozzle. The method may involve attaching a first end of at least one actuator to the nacelle nozzle, and attaching a second end of the actuator to an inner skin of the exhaust mixing structure. At least one shape memory alloy (SMA) tendon connected to the actuator first and second ends may be activated such that the SMA tendon longitudinally constricts to move the inner skin of the exhaust mixing structure slidably along a longitudinal path. This causes a portion of the exhaust mixing structure to be flexed into a path of flow exiting the nacelle nozzle.

Abstract: A method for determining the health of a structural element. The method includes providing a plurality of transducer elements arranged and disposed to permit measurement of vibration generated by at least one of the transducer elements at one or more of the other transducers elements. Vibration is induced with at least one transducer element. Vibration is measured at least one other transducer element, where the measured vibration corresponding to a vibratory path. At least one damage index value is calculated for each vibratory path in response to the measured vibration. At least one damage image is generated in response to the damage index value. The damage image assigns damage index values to each vibratory path. A damage location is determined from the damage image.

Abstract: A method for monitoring and diagnosing the health of a structure. The method includes providing a plurality of damage monitoring units each having at least one actuator, at least one sensor and a data collection device. The sensors are arranged and disposed to measure vibration produced by the actuator and provide a signal corresponding to the measured vibration to the data collection device. The actuator is activated and the vibration is measured with the sensor. The signal is compared to a reference signal and a damage index value is determined in response to the comparison between the signal and reference signal. The damage index value is transmitted for each vibratory path to a central processing device and the damage index values are analyzed for the plurality of damage monitoring units to determine the location of damage to the structure.

Abstract: An apparatus is provided that includes a body having a first wall and a second wall, at least one appending structure extending from an end of the body and at least one actuator positioned between the first and second walls. The actuator includes first end coupled to a portion of the body and a second end coupled to a portion of the appending structure. At least one shape memory alloy (SMA) wire is connected to and extends between the first and second ends of the actuator. The SMA wire is adapted to controllably constrict when activated by heat, whereby the constriction causes the appending structure to move from a first position to a second position.

Abstract: An apparatus is provided that includes a body having a first wall and a second wall, at least one appending structure extending from an end of the body and at least one actuator positioned between the first and second walls. The actuator includes first end coupled to a portion of the body and a second end coupled to a portion of the appending structure. At least one shape memory alloy (SMA) wire is connected to and extends between the first and second ends of the actuator. The SMA wire is adapted to controllably constrict when activated by heat, whereby the constriction causes the appending structure to move from a first position to a second position.