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Sunnyvale, CA, United States

Michaels J.E.,Georgia Institute of Technology | Lee S.J.,Acellent Technologies, Inc. | Croxford A.J.,University of Bristol | Wilcox P.D.,University of Bristol
Ultrasonics | Year: 2013

Most ultrasonic guided wave methods require tone burst excitations to achieve some degree of mode purity while maintaining temporal resolution. In addition, it is often desirable to acquire data using multiple frequencies, particularly during method development when the best frequency for a specific application is not known. However, this process is inconvenient and time-consuming, particularly if extensive signal averaging at each excitation frequency is required to achieve a satisfactory signal-to-noise ratio. Both acquisition time and data storage requirements may be prohibitive if responses from many narrowband tone burst excitations are measured. Here chirp excitations are utilized to address the need to both test at multiple frequencies and achieve a high signal-to-noise ratio to minimize acquisition time. A broadband chirp is used to acquire data at a wide range of frequencies, and deconvolution is applied to extract multiple narrowband responses. After optimizing the frequency and duration of the desired tone burst excitation, a long-time narrowband chirp is used as the actual excitation, and the desired tone burst response is similarly extracted during post-processing. Results are shown that demonstrate the efficacy of both broadband and narrowband chirp excitations. © 2012 Elsevier B.V. All rights reserved. Source

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 749.92K | Year: 2014

Acellent Technologies is developing a system for the US Navy that incorporates innovative ways to detect and track corrosion, measure clamping force and bolt preload in bolted joints typical of aircraft structures. Many of the corrosion inspection methods currently employed in the field to inspect magnesium housings involve disassembling the components and performing a visual inspection. Apart from being time-consuming, labor intensive, cumbersome and unreliable these inspections often lead to damage of the protective coating covering the surface during disassembly. Acellent Technologies is developing an accurate, reliable integrated health monitoring system capable of detecting, locating and sizing regions of corrosion in the area being monitored. The ultimate objective of the program will be to provide the U.S. Navy with a portable Corrosion Monitoring System (CMS) capable of efficiently monitoring regions of interest for degradation, thus mitigating the hazards associated with failure of critical aircraft components. Phase I demonstrated that the capability for detection of clamping force and bolt preload using a Hybridized SMART Layer. Phase II will focus on complete system development, testing and validation in collaboration with Sikorsky Aircraft Company and the U.S. Navy.

Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

ABSTRACT:In the past several years, Structural Health Monitoring (SHM) has emerged from the research environment into initial applications in a wide variety of fields. Before SHM systems can be implemented in an operational environment, there is a need for new methods and procedures to compensate for uncertainty in SHM systems arising from a variety of reasons, including component geometry, loading and boundary condition changes, aging effects etc. In this program Acellent proposes to develop an innovative Multi-Physics-Based Intelligence Sensing System for Fatigue and Fastener Crack Detection in Multi-Layer structures to address the uncertainities for detection. The goal will be to accurately detect, locate and characterize fatigue cracks as well as corner cracks originating from fastener holes in multi-layer structures. Phase I will focus on defining the overall SHM framework and developing methodologies to compensate for variability in an operational environment. The methods used will be practical for real-world applications and be applicable for robust operation of the SHM system in austere flight/field environments with limited maintenance and low false call rates. The program will be supported by Boeing for future implementation on aircraft structures in concurrence with the U.S. Air Force Aircraft Structural Integrity Program (ASIP) requirements.BENEFIT:The largest and nearest-term impact areas for the technology are inaccessible areas in todays aircraft. Economic factors drive the need to keep these vehicles in-service for longer periods of time, often well beyond their designed service life. As these structures age, there is an increasing need for inspection to ensure public safety, ensure combat readiness and schedule maintenance effectively. The high cost of owning and operating these systems provides incentives for enhancing the means of evaluating and monitoring their structural integrity. The big challenge to this industry is that it must maintain a high standard of safety with its fleet in an economic environment with cost-effectiveness that is intensely competitive. With the growing number of older aircraft in service, the business case for Structural Health Monitoring (SHM) retrofit applications is increasingly gaining more and more momentum. Retrofit applications focused on monitoring age-related degradation parameters like fatigue, corrosion and delamination are a key target of SHM. The target SHM technology is lightweight, easy to install and simple to use. The emphasis is not only on the development of further new SHM technologies, but also on testing the SHM systems robustness in representative environments to mature future service applications. The proposed system could potentially lead to significant savings in maintenance costs for aircraft (30-90% depending on application), can enhance the reliability of the structures and improve their efficiency, safety, and readiness. The proposed innovative, integrated inspection system, can efficiently and economically manage structural inspection data for the fleets of aging U.S. Air Force aircraft. The proposed work will be conducted in close collaboration with companies such as Boeing to ensure that this work will be directly beneficial to them.

Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2012

Acellent will develop High Speed Blast Impact Detector System-HVBIDS. The system will integrate high frequency sampling modules in the passive monitoring technique to respond to an impact event for generation of wave fields that would become the input of stress-strain reconstruction input in advanced finite element modeling process and perform benchmark study on the responding times. Acellent will develop real time calculation algorithm for the measurement of dynamic strain and stress caused by the impact. The main goal of HV-BIDS is for monitoring high speed blast impact event on the war fighter platforms in situ. HV-BIDS will provide: (1) Real time in-the-field stress measurements under blast loading conditions, (2) The sensor network will survive under blast pressure waves and complex geometrical deformation during or after the impact event, (3) The system can provide immediate measurement during the elastic-plastic transition on the surface of the structure, and (4) The system can provide input for validation of the 3D FEM and material deformation models.

Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2015

Composite and metallic airframe structures are susceptible to different damage types. Fatigue cracks are the major damage concerns for metallic airframe structures where as impact induced delamination and debond are major concerns for composite airframe structures. However, once damage is initiated, it can grow extremely fast and can lead to catastrophic failure of the structure. Hence, it is very important to develop Health Conscious Structures (HCS) using advanced Structural Health Monitoring (SHM) systems that are capable of detecting damage precursors at an earlier stage than currently possible as well as reliable prognostic tools to accurately predict the remaining useful life (RUL) of the structure. Acellent technologies in collaboration with the University of South Carolina and Bell Helicopters proposes to develop a novel and advanced multi-sensor based SHM system that will detect damage precursors, monitor damage progression and accurately predict the remaining useful life of the structure in near real-time. The proposed approach will be applicable for both metal and composite structures. The proposed system will be tested and demonstrated with metallic coupons in Phase-I of this project whereas composite coupons will be tested as part of Phase-II of this project.

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