We have developed numerous innovative solutions for complex engineering problems over the years.
Many of these projects have been performed in collaboration with leading academic researchers and are sponsored by
US government agencies. A list of sample R&D projects is highlighted here.
Leak Detection in International Space Station Module
Sponsor:
NASA Langley Research Center
The project initially consisted of calibrating the vibroacoustic model of the International Space Station (ISS) by
correlating experimental data, measured by NASA LaRC at specific sensor locations on a module of ISS, with numerical data,
predicted using our high frequency energy flow analysis (EFA)software, Comet EnFlow
TM.
...
Subsequently, new techniques were developed to
generate transfer matrix
that relates acoustic sources to sensor location responses.
The transfer matrix is then used in conjunction with acoustic
emission to detect leakages (sources). See |
NASA Spinoff 2015,
"Sound Modeling Simplifies Vehicle Noise Management."
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Sub-Structured, Meshless and Parametric Modeling of Vibroacoustic Systems
Sponsor:
NASA Langley Research Center
Collaborator:
Wayne State University
Aerospace structures are often subjected to a broad spectrum of mechanical and/or aerodynamic excitations and,
therefore, there is a need to develop techniques that is applicable for the resolution of vibroacoustic systems
over the entire frequency spectrum. A substructure-based modeling technique that
is applicable at all frequencies is developed and applied
...
for the solution of
complex dynamic systems. This method does not require traditional meshing, computationally very efficient,
and allows for rational
modeling of manufacturing variability.
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Failure Initiation Predictors for Reliability-Based Design of Hybrid Composite Materials
Sponsor:
Air Force Office of Scientific Research
Collaborator:
The University of Michigan
This project is concerned with the development of a novel failure initiation and progressive failure analysis (PFA)
modeling method for advanced composite structures, utilizing a fundamental physics based multiscale mechanics model.
First, experimental works have been performed at the University of Michigan
...
to understand the failure initiation
and the interaction of various failure mechanisms for composite laminate
structures under compression.
Based on the experimental observation, micromechanics model has been developed to predict the nonlinear lamina
level deformation and failure
response. Concurrently, PFA methodology combining physics-based failure prediction models and the discrete
cohesive zone method (DCZM) has been
developed for modeling laminated composite to account for all possible failure mechanisms and their interactions.
In addition,
probabilistic analysis capability has been implemented into the PFA methodology to account for material variability
and manufacturing inconsistencies.
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Hybrid Element Method for Mid-Frequency Analysis of Composite Structures Subjected to
Boundary Layer Loading
Sponsor:
NASA Langley Research Center
Collaborator:
Calvin College
In many situations, aerospace structures are subjected to a wide frequency spectrum of mechanical and/or acoustic
excitations and therefore, there is a need for the development of numerical modeling techniques that are applicable
for the resolution of dynamic response of complex systems spanning the entire frequency spectrum.
...
Further, the modeling of composite structures becomes more and more
important since many new
vehicle designs incorporate increased amount of composite structural components due to weight specific advantages of
composites.
This project
is directed towards the development of techniques that will allow the prediction of noise in the interior of an
enclosure such as aircraft due
to the transmission of turbulent boundary layer loading in the presence of composite structural components. This
innovative Hybrid Element
Method (HEM) solution tool for mid-frequency analysis, which utilizes elements of Dynamic Element Analysis
(DEA), together with conventional
low frequency FEM tools and
high frequency (Energy Flow Analysis) EFA tools, will provide a unified framework that is applicable for
the solution of full frequency
spectrum vibroacoustic prediction of nonuniform aerospace structures including metallic/composite
configurations, accurately and efficiently.
Read more
Identification and Reduction of Turbomachinery Noise
Sponsor:
NASA Glenn Research Center
Collaborators:
Michigan State University
Purdue University
Propulsion noise is a major contributor to the overall noise level near airports due to low flying aircraft
in the takeoff or landing phase of flight. The identification of propulsion noise of turbofan engines plays an
important role in the design. However, the noise generation mechanisms of a typical turbofan engine
are very complicated.
...
In this project, a generalized
acoustical holography (GAH) system that can handle aero-acoustic sources under stead-state and transient
conditions is developed.
Major accomplishments of the project include the development of efficient methods for the generation of transfer
matrix that relates
sources to sound pressure field measured using surface mounted microphones, application of innovative filtering
techniques of
measurement data using de-noising techniques, and the development of extensive regularization methods.
Read more
Hybrid Element Method for Mid-Frequency Vibroacoustic Analysis
Sponsor:
NASA Langley Research Center
Collaborator:
Calvin College
An innovative, accurate and efficient Hybrid Element Method (HEM) is developed for mid frequency vibroacoustic
analysis of non-uniform aerospace structures including metallic/composite configurations. The development is
based on the concept that by using transcendental functions based on the exact
(or near exact) solutions of
...
free wave equations and statistical phase function as
interpolation functions,
the mid frequency problems can be resolved using finite element models. When combined with low and high
frequency analysis
tools, this offers a unified framework for the full frequency spectrum, vibroacoustic analysis of aerospace systems
accurately and
efficiently using the same finite element database.
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Vehicle Noise Predictions Using Energy Finite Element Analysis
Sponsor:
NASA Langley Research Center
Collaborator:
Purdue University
The project is directed towards the development and validation of a numerical technique based on Energy Flow Analysis
(EFA) for the analysis of high frequency vibroacoustic problems. The energy flow equations are solved using
fintie element methods for structural and acoustic domains. Additionally, boundary element method
is also used to model acoustic domains.
...
Major accomplishments of the project include
the development of a new method
for interior noise prediction, development of an extensive library of structural and noise control elements,
development of the joint
element, development and incorporation of the energy boundary element method for the modeling of acoustic domain,
development of a hybrid
method for the accurate modeling of local excitation, efficient solution methods, and development of method
for the automatic
identification of point, line and area junctions at geometric and material discontinuities.
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Boundary and Finite Element Models for the Application of Nearfield Acoustical Holography
Sponsor:
NASA Langley Research Center
Collaborators:
Office of Naval Research
Purdue University
Evaluation of noise sources is difficult when there are multiple sources and the interaction among them
is complex. Holography is an inverse solution technology in which one can identify and rank sources using near field
sound measurement. Holography has been traditionally applied for simple geometry
such as planar, cylindrical or spherical surfaces.
...
In this project,
identification of coherent,
incoherent and partially coherent sources in complex structures using measurements taken using flexible
non-planar layout is developed.
Extensive regularization techniques (such as Tikhonov, Morozov principle, Generalized Cross Validation etc.)
are developed as part of
the project.
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Development of a Finite Element Model for Passive and Active Noise Control Design Procedures
Sponsor:
NASA Langley Research Center
Collaborator:
Purdue University
Methods are developed to analyze and optimize sound in elastic-porous (e.g., foam), solid and fluid domains.
Unlike approximate solution tools that have been used for the modeling of foam type materials, methods based on rigorous
physical and mathematical principles are developed. The resulting development
is used for the analysis of noise controls
...
treatments in applications such as vehicle sound
insulation, mufflers and ducts, headliners, seats, carpets, trim lining, and enclosure liners.
See | NASA Spinoff 2000,
"The Imagery of Sound."
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