Abstract: Employing methodologies and systems to detect damage initiation and growth inside a composite material (matrix cracking, delamination, fiber break, fiber pullout, etc.) wherein damage produces high-frequency acoustic emission (AE) waves that are transported to recording sensors along with relatively lower frequency waves representing the flexural deformation of the impacted composite structure.

Abstract: An in-situ fiber-optic temperature field measurement is disclosed that can allow process monitoring and diagnosis for thermoplastic composite welding and other applications. A distributed fiber-optic sensor can be permanently embedded in a thermoplastic welded structure when it is welded and left there to perform lifelong monitoring and inspection. The fiber optic sensor can include a dissolvable coating, or a coating matched to the composite material to be welded. Other applications include in-situ fiber-optic temperature field measurement on thermoset composite curing (autoclave), for thermoplastic and thermoset composites during compression molding, and for fiber-optic field measurements on freeze/thaw of large items of public health interest, such as stored or transported foodstuffs.

Abstract: A new vibration test-cell that allows a static load to be applied simultaneously with lateral vibration coupled with in-situ microscopy that allows for the ability to open a fatigue crack up to a desired gap, as well as generate acoustic emission (AE) from vibration excitation, micro-fracture events are captured by the AE measurement while the physical observation of the crack faying surfaces is performed in-situ with an optical microscope embedded in the test cell.

Abstract: Detection, identification, and monitoring of various composite-damage types such as impact damage, delaminations, etc. using angle-beam coupled guided waves and methods and systems that permit excitation with angle-beam techniques of certain composite-material guided-wave modes that cannot be excited in isotropic metals with angle-beam methods.

Abstract: The current disclosure determines if structural faults exist and extracts geometric features of the structural faults from acoustic emission waveforms, such as crack length and orientation, and can evaluate the structural faults online, during normal operation conditions.

Abstract: A new vibration test-cell that allows a static load to be applied simultaneously with lateral vibration coupled with in-situ microscopy that allows for the ability to open a fatigue crack up to a desired gap, as well as generate acoustic emission (AE) from vibration excitation, micro-fracture events are captured by the AE measurement while the physical observation of the crack faying surfaces is performed in-situ with an optical microscope embedded in the test cell.

Abstract: The current disclosure determines if structural faults exist and extracts geometric features of the structural faults from acoustic emission waveforms, such as crack length and orientation, and can evaluate the structural faults online, during normal operation conditions.

Abstract: Method and apparatus estimate the length of a fatigue crack in sheet metal structures from individual acoustic emission (AE) signals without recourse to the AE signal history or AE signal amplitude. AE energy generated at one crack tip travels to the other tip and establishes a standing wave pattern that has a characteristic dominant frequency which depends on the crack length. Therefore, crack length information can be recovered from the analysis of the standing wave frequency present in the high-frequency AE signals. We found that the AE signals predicted through numerical simulation have embedded in the high-frequency information that can be related directly to crack size. This information is manifested as peaks in the frequency spectrum that shift as crack length changes. The predictive AE models were tuned against experimentally observed AE signals and a methodology for predicting crack length from AE signals was established.

Abstract: A new vibration test-cell that allows a static load to be applied simultaneously with lateral vibration coupled with in-situ microscopy that allows for the ability to open a fatigue crack up to a desired gap, as well as generate acoustic emission (AE) from vibration excitation, micro-fracture events are captured by the AE measurement while the physical observation of the crack faying surfaces is performed in-situ with an optical microscope embedded in the test cell.

Abstract: Employing methodologies and systems to detect damage initiation and growth inside a composite material (matrix cracking, delamination, fiber break, fiber pullout, etc.) wherein damage produces high-frequency acoustic emission (AE) waves that are transported to recording sensors along with relatively lower frequency waves representing the flexural deformation of the impacted composite structure.

Abstract: Detection, identification, and monitoring of various composite-damage types such as impact damage, delaminations, etc. using angle-beam coupled guided waves and methods and systems that permit excitation with angle-beam techniques of certain composite-material guided-wave modes that cannot be excited in isotropic metals with angle-beam methods.

Abstract: Computationally efficient, highly accurate, and cost-effective approach for detection of damage in a structure is described. Methods include a combined analysis in both global and local regions of a structure to predict the received wave signals at a location due to scattering of Lamb waves at a damage site. Through comparison of an actual received wave signal with the predicted signals, identification of damage location and/or type can be provided. Methods can be particularly beneficial when considering damage assessment in a complex structure that includes plate-like structures that include an extension off of a base plate, e.g., a stiffened structure.

Abstract: Structural health monitoring systems and methods are described that incorporate one or more acoustic black holes in a sensing capacity. The acoustic black hole provides low- or no-reflection capabilities combined with high displacement of an edge upon excitation. The sensor can be utilized to differentiate in-plane acousto-ultrasonic wave excitations from out-of-plane excitations as well as to separate the in-plane and out-of-plane components of an excitation acousto-ultrasonic wave. Sensors can incorporate features such as mode selectivity, omnidirectional sensing, frequency tunability, quasi-static strain insensitivity, and mechanical amplification.

Abstract: The current disclosure determines if structural faults exist and extracts geometric features of the structural faults from acoustic emission waveforms, such as crack length and orientation, and can evaluate the structural faults online, during normal operation conditions.

Abstract: The current disclosure determines if structural faults exist and extracts geometric features of the structural faults from acoustic emission waveforms, such as crack length and orientation, and can evaluate the structural faults online, during normal operation conditions.

Abstract: Disclosed are composite structure health monitoring (SHM) systems that incorporate aspects of both a passive SHM system and an active SHM system. Systems provide a route for continuous monitoring to recognize potentially damaging events as well as to determine the location and intensity of damage in those instances in which the event does cause damage to the structure. Systems can provide improved monitoring with a low space and weight requirement, for instance when utilized for SHM of aircraft.

Abstract: An in-situ fiber-optic temperature field measurement is disclosed that can allow process monitoring and diagnosis for thermoplastic composite welding and other applications. A distributed fiber-optic sensor can be permanently embedded in a thermoplastic welded structure when it is welded and left there to perform lifelong monitoring and inspection. The fiber optic sensor can include a dissolvable coating, or a coating matched to the composite material to be welded. Other applications include in-situ fiber-optic temperature field measurement on thermoset composite curing (autoclave), for thermoplastic and thermoset composites during compression molding, and for fiber-optic field measurements on freeze/thaw of large items of public health interest, such as stored or transported foodstuffs.

Abstract: Computationally efficient, highly accurate, and cost-effective approach for detection of damage in a structure is described. Methods include a combined analysis in both global and local regions of a structure to predict the received wave signals at a location due to scattering of Lamb waves at a damage site. Through comparison of an actual received wave signal with the predicted signals, identification of damage location and/or type can be provided. Methods can be particularly beneficial when considering damage assessment in a complex structure that includes plate-like structures that include an extension off of a base plate, e.g., a stiffened structure.

Abstract: The current disclosure determines if structural faults exist and extracts geometric features of the structural faults from acoustic emission waveforms, such as crack length and orientation, and can evaluate the structural faults online, during normal operation conditions.

Abstract: Structural health monitoring systems and methods are described that incorporate one or more acoustic black holes in a sensing capacity. The acoustic black hole provides low- or no-reflection capabilities combined with high displacement of an edge upon excitation. The sensor can be utilized to differentiate in-plane acousto-ultrasonic wave excitations from out-of-plane excitations as well as to separate the in-plane and out-of-plane components of an excitation acousto-ultrasonic wave. Sensors can incorporate features such as mode selectivity, omnidirectional sensing, frequency tunability, quasi-static strain insensitivity, and mechanical amplification.