INNOVATIONS
R&D Projects
We have developed many 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. Some of these projects are highlighted in this section.
Leak Detection in International Space Station Module
Sponsor:NASA
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 CTC’s high frequency
energy finite element method (EFEM) software, Comet EnFlow. Subsequently, new techniques were developed to generate transfer matrix (TM)
that relates acoustic sources to sensor location responses. The TM is then used in conjunction with acoustic emission to detect leakages
(sources).
Sound Modeling Simplifies Vehicle Noise Management  NASA Spinoff 2015
SubStructured, Meshless and Parametric Modeling of Vibroacoustic Systems
Sponsor:NASA
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 substructurebased 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.
Failure Initiation Predictors for ReliabilityBased 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
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 physicsbased 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.
Hybrid Element Method for MidFrequency Analysis of Composite Structures Subjected to Boundary Layer Loading
Sponsor:NASA
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 midfrequency analysis, which utilizes elements of DEA, together with conventional low frequency FEM tools and
high frequency EFEM 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.
Identification and Reduction of Turbomachinery Noise
Sponsor:NASA
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 aeroacoustic sources under steadstate 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 denoising techniques, and the development of extensive regularization methods.
Hybrid Element Method for MidFrequency Vibroacoustic Analysis
Sponsor:NASA
Collaborator:
Calvin College
An innovative, accurate and efficient Hybrid Element Method (HEM) is developed for mid frequency vibroacoustic analysis of nonuniform
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 (FEM) and high frequency (EFEM) 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.
Vehicle Noise Prediction Using Energy Finite Element Analysis
Sponsor:NASA
Collaborator:
Purdue University
The project is directed towards the development and validation of a numerical technique based on Energy Finite Element Method (EFEM)
for the analysis of high frequency vibroacoustic problems. 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 space, 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.
Boundary and Finite Element Models for the Application of Nearfield Acoustical Holography
Sponsor:NASA
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 nonplanar layout is developed.
Extensive regularization techniques (such as Tikhonov, Morozov principle, Generalized Cross Validation etc.) are developed as part of
the project.
Development of a Finite Element Model for Passive and Active Noise Control Design Procedures
Sponsor:NASA
Collaborator:
Purdue University
Methods are developed to analyze and optimize sound in elasticporous (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.
The Imagery of Sound  NASA Spinoff 2000
Publications

Comparison of Methods for High Frequency Acoustic Radiation Analysis, InterNoise and NoiseCon Congress and Conference Proceedings, INCE, 10051192, 10471057, 2017.
Application of Energy Flow Methods for Vibroacoustic Analysis, Proceedings of NoiseCon 2016, Providence, Rhode Island, 2016.
Comparison of Methods for Solution of High Frequency Vibroacoustic Problems, Proceedings of InterNoise 2015, San Francisco, California, 2015.
Application of Fourier Spectral Element Method for the Solution of Vibroacoustic Problems, Proceedings of NoiseCon 2014, Fort Lauderdale, Florida, 2014.
Calibration of International Space Station (ISS) Node 1 VibroAcoustic Model, NASA report: NASA/CR–2014218248, 2014.
Calibration of International Space Station (ISS) Node 1 VibroAcoustic Model—Report 2, NASA report: NASA/CR–2014218249, 2014.
Progressive Failure Analysis Method of a PiJoint with Uncertainties in Fracture properties, Proceedings of the 53rd AIAA/AME/ASCE/AHS/ASC Structures, Structural Dynamics, and Material Conference, AIAA, Honolulu, Hawaii, USA, 2012.
Effect of stacking sequence on the compressive strength and failure mode in fiber reinforced multidirectional laminated composites, American Society for Composites 27th Technical Conference/ 15th USJapan Conference on Composite Materials/ ASTMD30 Meeting, Arlington, Texas, October 2012.
Reliabilitybased Progressive Failure Analysis for Advanced Composite Structures, 26th Annual Technical Conference of the American Society for Composites 26th Technical Conference, Montreal, Canada, 2011.
Probabilitybased Analysis for Modeling Failure Mode Interaction and Progressive Damage in Laminated Composite Structures with an Initial Delamination, 18th International Conference on Composite Materials, Jesu Island, Korea, August 2011.
Computational Modeling of PiJoint Failure Including Uncertainties in Mechanical and Geometric Properties, AIAA20111722, Proceedings of AIAA/ASME/ASCE/AHS/ASC Structural Dynamics and Materials Conference, Denver, Colorado, April 2011.
Investigation of Failure Mode Interaction in Laminated Composites Subjected to Compressive Loading, AIAA20111792, Proceedings of AIAA/ASME/ASCE/AHS/ASC Structural Dynamics and Materials Conference, Denver, Colorado, April 2011.
Reconstruction of Noise Sources in a Ducted Fan Using Generalized Acoustical Holography, Paper No: 2010010416, 2010 SAE World Congress, Detroit, Michigan (also published in Optimization, Optical Mean and Nondestructive Testing Technique, SAE 2010), 2010.
Denoising and Regularization in Generalized NAH for Turbomachinery Acoustic Noise Source Reconstruction, Noise Control Engineering Journal (Invited Contribution), Volume 58, 1, pp. 93103, 2010.
High Frequency VibroAcoustic Analysis Using Energy Finite Element Method, SAE Journal of Passenger Cars, Paper No: 2009010771, 2009.
Nearfield Acoustical Holography for Noise Source Identification in Turbomachinery, Proc IEEE SAS conference, 2009.
Model Order Reduction Using Basis Expansions for Nearfield Acoustic Holography, Paper No: 2009012174, SAE Noise & Vibration Conference, St. Charles, Illinois, 2009. hr>Application of Energy Finite Element Method for High Frequency Vibroacoustic Analysis, Paper No: NC08211, NoiseCon2008, Dearborn, Michigan, 2008.
Identification and Reduction of Turbomachinery Noise Using Integrated Nearfield Acoustical Holography and Active Noise Control Techniques, Proceedings of Noisecon2008, Dearborn, Michigan, 2008.
Denoising and Regularization in NAH for Turbomachinery Noise Source Reconstruction, Proceedings of Noisecon2008, Dearborn, Michigan, 2008.
Vibroacoustic Analysis Using Hybrid Energy Finite Element and Boundary Element Methods, Paper No: 2007012177, Proceedings of SAE Noise & Vibration Conference, St. Charles, Illinois, 2007.
Sound Package Analysis Using Energy Finite Element Method, Paper No: 2007012309, Proceedings of SAE N & V Conference, St. Charles, Illinois, 2007.
Correlation between Microscopic Characteristics and Macroscopic Acoustic Performance of Acoustical Materials, Proceedings of InterNoise 2006, Honolulu, Hawaii, December 2006.
Interior Noise Prediction Based on Energy Finite Element Method, SAE Noise & Vibration Conference, Traverse City, Michigan, Paper No: 2005012332, 2005.
Improving Acoustical Performance of Poroelastic Materials, SAE N & V Conference, Traverse City, Michigan, Paper No: 2005012283, 2005.
Interior Noise Prediction Based on Energy Finite Element Method, SAE N & V Conference, Traverse City, Michigan, Paper No: 2005012332, 2005.
Aeroacoustic Noise Source Identification Using Acoustical Holography, SAE N & V Conference, Traverse City, Michigan, Paper No: 2005012499, 2005.
High Frequency Interior Noise Prediction Model Based on Energy Finite Element Analysis, MSC.Software Americas VPD Conference, VPD04105, 2004.
Modeling Noise Control Materials, SAE Noise and Vibration Conference, Paper No: 2003011580, 2003.
Sound Transmission Loss Analysis of an Automotive Dash by Finite Element Method, SAE Noise and Vibration Conference, Paper No: 2003011613, 2003.
Noise Source Identification in an Automotive Powerplant, SAE N & V Conference, Paper No: 2003011695, 2003.
A Method to Evaluate the Acoustic Performance of Lightweight Sound Packages for Automotive Interior, SAE N & V Conference, Paper No: 2003011404, 2003.
Identification of Noise Sources in an Automotive System, Society of Experimental Mechanics Annual Conference, Charlotte, North Caroline, Paper No: 8, 2003.
Sound Power Sensitivity Analysis and Design Optimization Using BEM, SAE Journal of Passenger Cars, Paper No: 2003011455, pp.16271632, 2003.
Formulation of a Numerical Process for Acoustic Impedance Sensitivity Analysis Based on the Indirect Boundary Element Method, Engineering Analysis with Boundary Elements (Invited Contribution), Vol. 27, pp. 671681, 2003.
A Fast Algorithm for Evaluating BEM Based Nearfield Acoustic Holography Transfer Functions, SAE Journal of Passenger Cars, Paper No: 2003011696, pp. 21672174, 2003.
Development of General SEA Templates for FourDoor Passenger Cars, SAE Journal of Passenger Cars, Paper No: 2003011558, pp. 18601870, 2003.
On the Evaluation of Radiated Sound Field of Engine Covers, SAE Journal of Passenger Cars, Paper No: 2000011412, pp. 15001594, 2001.
Acoustic Tuning of Lightweight Vehicle Interior Systems, SAE Journal of Passenger Cars, Paper No: 2001011628, pp. 21422151, 2001.
Noise Source Identification in a Cab Interior, SAE Journal of Passenger Cars, Paper No: 2001011630, pp. 21572162, 2001.
Effect of Seating Foam on the Acoustical Behavior of an Earthmoving Cab, SAE 2001011560, 2001.
An Analysis of Regularization Errors in Generalized Nearfield Acoustical Holography, SAE 2001011616, 2001.
Generalized Noise Source Reconstruction, Paper No: nc01078, NoiseCon 2001, Portland, Maine, Oct. 2931, 2001.
Optimization of Sound Absorption and Transmission Loss of Elastic Porous Materials, Paper No: NC01079, NoiseCon 2001, Portland, Maine, 2001.
Identification of Incoherent Noise Sources, Proceedings of the ASME International Mechanical Engineering Conference & Exposition, New York, 2001.
Computation of Sound Transmission Loss and Absorption Coefficient of Multilayer Systems, ASME, New York, 2001.
An Integral Experimental/Numerical Noise Source Identification Technique, Proceedings of International Modal Analysis Conference XVIII: A Conference on Structural Dynamics, San Antonio, Texas, pp. 17631768, 2000.
Creating virtual spatial audio via scientific computing and computer vision, ASA/NOISECON Conference Proceedings, Newport Beach, CA, 2000.
Noise Source Identification in an Aircraft Using Nearfield Acoustical Holography, Proceedings of the American Institute of Aeronautics and Astronautics Conference, AIAA20002097, 2000.
Identification of Incoherent Noise Sources in Complex Structures, Proceedings of the First International AutoSEA Users Conference, San Diego, CA, pp.177185, 2000.
The Use of PieceWise Continuous Polynomial Basis Function for the Reduction of Integral Equations in Thermoelastic Analysis, Computers and Structures, 77, pp.601614, 2000.
A Computational Acoustic Field Reconstruction Process Based on an Indirect Boundary Formulation, The Journal of the Acoustical Society of America, 108(5), pp. 21672178, 2000.
Interior nearfield acoustical holography in flight, The Journal of the Acoustical Society of America, 108 (4), pp. 14511463, 2000.
An Efficient Indirect Boundary Element Method Solution for MultiFrequency Acoustic Analysis, International Journal for Numerical Methods in Engineering, Vol. 44, pp. 5976, 1999.
Numerical Implementation and Application of a Coupling Algorithm for StructuralAcoustic Models with Unequal Discretization and Partially Interfacing Surfaces, Finite Elements in Analysis and Design, 32, pp. 257277, 1999.
Development of an Equivalent Force Method and an Application in Simulating the Radiated Noise from an Operating Diesel Engine, Shock and Vibration, Vol. 6, Number 3, pp. 113123, 1999.
Keeping Truck Cabs Quiet, Machine Design, S18S21, 1999.
A Computational Acoustic Field Reconstruction Process based on an Indirect Variational Boundary Element Formulation, ASME IMECE, Nashville, TN, November pp. 4350, 1999.
Interior NAH in flight, Proceedings of the 6th International Congress of Sound and Vibration, Copenhagen, Denmark, July 1999.
A technique for Extracting Natural Frequencies of Acoustical Cavities, Proceedings of NOISECON 98, pp. 181186, 1998.
Transient Noise Analysis Using an Indirect Boundary Element Formulation, Proceedings of NOISECON 98, pp. 643648, 1998.
On the Extraction of Acoustic Eigenfrequencies by the Boundary Element Method, Proceedings of ICES98, Atlanta, Georgia, pp. 217222, 1998.
Formulation, Implementation and Validation of Multiple Connection and Free Edge Constraints in an Indirect Boundary Element Formulation, Journal of Sound and Vibration, Vol 201(1), pp. 137152, 1998.
An Indirect Boundary Element Technique for Exterior Periodic Acoustic Analysis, SAE Transactions – Journal of Passenger Cars, pp. 615620, 1998.
An Indirect Boundary Element Formulation for MultiValues Impedance Simulation in Structural Acoustics, Applied Mathematical Modelling, 22, pp. 379393, 1998.
Analysis of Periodic Acoustic Problems with Double Sided Impedance Condition, Proceedings of NOISECON 97, pp. 145150, 1997.
Boundary Element Method for High Frequency Acoustic Analysis, Proceedings of the ASME Noise Control and Acoustics Division, NCAVol. 24, pp. 309313, 1997.
On the Boundary Element Formulation for Periodic Acoustic Analysis with Impedance Boundary Condition, Boundary Element Technology XII (Eds. J. I. Frankel, C. A. Brebbia and M. A. H. Aliabadi), Computational Mechanics Publications, Southampton, pp. 175182, 1997.
A Formulation of Unequal Impedance Boundary Conditions in Boundary Element Acoustics (Invited paper), Proceedings of the ASME Noise Control and Acoustics Division, NCAVol.24, pp. 337342, 1997.
Numerical Computation of Noise Transmitted Inside a Payload Fairing due to External Reverberant Field Excitation, Proceedings of NOISECON 96, pp. 775778, 1996.
Numerical Simulation of MultiFrequency Acoustic Problems Using Indirect Boundary Element Method, Proceedings of NOISECON 96, pp. 745750, 1996.
Radiation Efficiency Calculations for Verification of Boundary Element Acoustic Code, Noise Control Engineering Journal, Vol 44 (5), pp. 225223, 1996.
Application of BEM to Some Dynamic Problems of Saturated Porous Media, Computer Methods in Geomechanics (Eds. Siriwardane and Zaman), Balkerma, Rotterdam, pp. 7989, 1994.
Acoustic Sensitivity Analysis Using Boundary Elements and Dynamic Response, MSC World User's Conference Proceedings, pp. 114, 1994.
Boundary Element Formulation for Structural Acoustic Including Mean Flow Effects, ASME Winter Annual Meeting, New Orleans, Computational Methods for Fluids/Structure Interaction, AMDVol 178, ASME, pp. 3950, 1993.
Development of BEM for Structural Acoustic analysis in the Presence of Mean Flow, Second U.S. National Congress on Computational Mechanics, Washington, D.C., 1993.
Stress Intensity Factors for Thermally Loaded Cracks in Three Dimensional Solids, International Journal for Numerical Methods in Engineering, Vol. 36, pp. 19091926, 1993.
BEM Analysis of FreeVibration Problems Using Polynomial Particular Integrals, International Journal of Solids and Structures, Vol. 29, No. 16, pp. 20232037, 1992.
Eigenvalue Analysis by Boundary Element Method, Advanced Dynamic Analysis by Boundary Element Method (Eds. P. K. Banerjee, A. S. Kobayashi), Elsevier Applied Science Publishers, Essex, England, pp. 283320, 1992.
Boundary Element Analysis of Cracks in Thermally Stressed Planar Structures, International Journal of Solids and Structures, Vol. 29, No. 18, pp. 23012317, 1992.
Polynomial Particular Solutions Based Boundary Element Analysis of Acoustic Eigenfrequency Problems, International Journal for Numerical Methods in Engineering, Vol. pp. 17871802, 1992.
The Analysis of Rotating Solids with Cracks by the Boundary Element Method, International Journal of Solids and Structures, Vol. 28, No. 9, pp. 11551170, 1991.
Computation of Stress Intensity Factors for Interfacial Cracks, Engineering Fracture Mechanics, Vol. 40, No. 1, pp. 89103, 1991.