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Hajzargerbashi T.,University of Arizona | Kundu T.,University of Arizona | Bland S.,NextGen Aeronautics, Inc.
Ultrasonics | Year: 2011

Conventional triangulation techniques fail to correctly predict the acoustic source location in anisotropic plates due to the direction dependent nature of the elastic wave speeds. To overcome this problem, Kundu et al. [1] proposed an alternative method for acoustic source prediction based on optimizing an objective function. They defined an objective function that uses the time of flight information of the acoustic waves to the passive transducers attached to the plate and the wave propagation direction (θ) from the source point to the receiving sensors. Some weaknesses of the original algorithm proposed in Ref. [1] were later overcome by developing a modified objective function [2]. A new objective function is introduced here to further simplify the optimization procedure and improve the computational efficiency. A new algorithm for source location is also introduced here to increase the source location accuracy. The performance of the objective function and source location algorithm were experimentally verified on a homogeneous anisotropic plate and a non-homogeneous anisotropic plate with a doubler patch. Results from these experiments indicate that the new objective function and source location algorithm have improved performance when compared with those discussed in Refs. [1,2]. © 2010 Elsevier B.V. All rights reserved.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.45K | Year: 2007

NextGen proposes an approach to significantly enhance aeroelastic analysis capabilities over what is commonly available in linear analysis environments such as NASTANTM The approach to accomplish this builds upon an existing software framework that allows the integration of varying-fidelity aerodynamic modeling capability with varying videlit structural models. The approach utilizes inherently nonlinear aerodynamic predictions schemes that are incorporated into the aeroelastic solution strategy. Potentially large (geometrically nonlinear) structural deflections under the influence of nonlinear aerodynamic can be analyzed using the approach. Hierarchical levels of analysis capabilities are included, ranging from simple yet powerful empirical approaches to the complete coupling of high-order CFD codes and nonlinear structural models. An aeroservoelastic solution framework will be developed in Phase I resulting in a prototype nonlinear aeroelasticity method suitable for a proof-of-concept demonstration. The developed methods will be demonstrated on test cases of recent research interest, such as the Active Aeroelastic Wing (AAW) F/A-18 aircraft.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 98.24K | Year: 2007

NextGen is proposing a simple yet powerful damage identification technique for advanced composite structures. We propose to develop a damage index based on vibration signature comparison with original signatures of the structure. Our approach is to autonomously perform damage detection as well as identification of non-service loading events by minimum number of sensors. We will start with the preliminary work done by Dr. Mal at UCLA and improve upon it to achieve the objective of cradle-to-grave degradation monitoring. The overall goal of the program is to develop an accurate, rapid, inexpensive method for detection of composite internal damage including bonds strength in built-up structures. The objective of the Phase I program is to develop and demonstrate that the proposed technique is accurate and reliable. We will achieve TRL of 2 in Phase I and subsequent technology transition to TRL of 4 in Phase II. NextGen's strength lies in related prior work, an in-depth understanding of damage modes in advanced composite structures, and comprehensive knowledge of damage detection techniques. Dr. Ajit Mal of the Mechanical Engineering Department at UCLA has an exceptional background in structural health monitoring built on decades of cutting edge research in NDE


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 599.95K | Year: 2008

NextGen Aeronautics, after achieving promising results in Phase I, is proposing a simple yet powerful damage identification technique for honeycomb advanced composite structures in Phase II. The proposed Phase II program is focused to achieve at least TRL of 5 and quickly commercialize technology in Phase III. The specific objectives are: 1) Improve Raleigh –Lamb (RL) wave based statistical detection technology; 2) Reduce NDE time by field usable automated data collection; 3) Develop end-to-end system software; 4) Develop detailed early commercialization plan. The Phase II development will provide a significant improvement in functionality of the system and put strong emphasis on process automation. NextGen is pursuing teaming arrangement with Boeing and Northrop Grumman to test the proposed system in realistic environment. During Phase I, the NextGen team established feasibility of the proposed system by evaluating it on a honeycomb plate, a common construction used in many secondary structures of aircraft. NextGen has chosen an outstanding team that has considerable prior experience, an in-depth understanding of damage modes in advanced composite structures, and comprehensive knowledge of damage detection techniques. Our team's combined expertise in health monitoring systems and our relationship with system integrators will ensure near-term technology transition.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: STTR | Phase: Phase II | Award Amount: 100.00K | Year: 2005

Encouraged by Phase I accomplishments, the proposed Phase II program will significantly mature and align the development of a Space Qualified Non-Destructive Evaluation & Health Monitoring system with the needs of NASA. We are systematically working to improve the TRL to 5 at the end of Phase II and formulate commercialization and product development strategy beyond Phase II. The proposed health monitoring system features three innovative technologies: excitation of preferential Lamb/Rayleigh wave modes; utilization of phased array concepts; and utilization of software algorithms rather than hardware for beam forming and signal analysis. The ability to detect cracks, corrosion, disbonds, and cracks under bolts for a stiffened panel was demonstrated in Phase I. The detection methods used were pitch-catch, pulse-echo, phased array, and electromechanical impedance. To efficiently and cost-effectively achieve Phase II objectives, NextGen has teamed with Lockheed Martin Space Systems - Michoud Operations to test the proposed system in realistic environment. A cryogenic, composite LOX tank, built by Lockheed Martin for the X-34, is currently in a test fixture at NASA Marshall and will be used for evaluating our system. Additional tests will be performed to validate the durability and survivability of the system for space certification.

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