Dr. Ali Abdul-Aziz Profile

Dr. Ali Abdul-Aziz

Associate Professor at Kent State Univ

SPIE Involvement:

Conference Program Committee | Author | Science Fair Judge

Publications (35)

Proceedings Article | 18 April 2022 Presentation + Paper

Engine rotor health monitoring: an experimental approach to fault detection using a machine fault simulator

Ali Abdul-Aziz, Stanley Nerkowski, Tristian Little

Proceedings Volume 12047, 1204716 (2022) https://doi.org/10.1117/12.2614950

KEYWORDS: MATLAB, Failure analysis, Vibrometry, Analytical research, Aerospace engineering, Actuators, Performance modeling, Particles, Manufacturing, Inspection

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Proceedings Article | 18 April 2022 Presentation + Paper

Turbofan engine performance simulation study under selected failure scenarios of rotating and hot sections components

Ali Abdul-Aziz, Stanley Nerkowski, Isaac Davanzati

Proceedings Volume 12047, 1204718 (2022) https://doi.org/10.1117/12.2614953

KEYWORDS: Failure analysis, Thermodynamics, Fluctuations and noise, Device simulation, Analytical research, Manufacturing, Digital recording, Data acquisition, Aerospace engineering, Visualization

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Engine technology advancements is a continuous prospects that manufacturers strive to maintain and improve to ensure better reliability, fuel efficiency and optimum operational capabilities. Primary performance parameters such as altitude and Mach number define the operational set points for the engine. The main aim of these efforts is to introduce the production of adequate thrust output to allow safe and stable maneuver of operation. Improving the efficiency and minimizing the operation cost via fuel savings is a key factor for a successful turbofan engine. The current study is to take on analyzing the performance of a high bypass ratio turbofan with the use of Akira DGEN 380 engine simulator [1-2]. This engine simulator is a key part of the laboratory within the college of Aeronautics and Engineering at Kent State University, Ohio and is essential in understanding the thermodynamic and aerodynamics properties of engine components. Moreover, the purpose of this project is to examine changes in engine performance under failure of components that impact the operation of the aircraft. This is done by simulating the aircrafts flight path and recording the engine key operating parameters throughout the flight. We are able to deduce the change in performance when we compare these simulations to a normal flight. Conditions such as specified components unexpected failures under a quantified flight path are being investigated to assess the performance of the engine under such operational circumstances. The typical flight duration for a private light jet is about two hours, and this simulation includes modeling a trip from Cleveland, OH to Washington D.C. During this flight, the maximum cruise altitude of twenty-three thousand feet traveling at about two hundred and fifty miles per hour is reached. The operational evaluation of the engine was assessed during this flight path and results pertaining to failure diagnosis based on the engine response obtained from the virtual test bench are presented and discussed.

Proceedings Article | 22 March 2021 Paper

Analytical and experimental verification of environmental barrier coating (EBC) covering crack propagation, failure mechanisms, and life modeling

Ali Abdul-Aziz, Samir Mustapha, Ali Fakha

Proceedings Volume 11592, 115920R (2021) https://doi.org/10.1117/12.2585384

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Gas turbine engines undergo very harsh operating environmental conditions, and this leads to various issues related to components materials strength limitations, degradation, cracking, and other durability problems. Under such circumstances, a robust material design is required to prevent these critical components from failing in service and preventing catastrophic events from taking place. The robust design must enhance component durability, which could be degraded due to material processing defects, variability in material properties, in-service loads, and operating environment. To encounter and manage these durability issues, materials scientists and engineers that are involved in this field along with engine makers are continuously working on developing protective materials to alleviate and increase materials damage tolerance and prevent components failure. Ceramic matrix composites (CMC) are now materials of choice for gas turbine engine design and manufacturing. The CMC has a good capability in operating at high temperatures up to 1500 °C which is within the norm of gas turbine engine operation and it is much lighter compared to metals. Good impact resistance and stability at high operating temperatures make the silicon carbide (SiC) ceramic matrix composite system a desirable option for jet engines [1]. However, CMC’s when they undergo the degradation process that typically includes coating interface oxidation as opposed to a moisture-induced matrix which is generally seen at a higher temperature. Additionally, other factors such as residual stresses, coating process-related flaws, and casting conditions may influence the degradation of their mechanical properties. These durability considerations are being addressed by introducing a highly specialized form of environmental barrier coating (EBC) that is being developed and explored in particular for hightemperature applications greater than 1100 °C [2]. In this paper, a CMC substrate is being evaluated for failure under supportive protection of EBC coatings. The primary aim is to identify the crack propagation phenomenon, the sequence of failure of the EBC and assess the life the CMC substrate. An analytical simulation applying the extended finite element method (XFEM) in ABAQUS software [3] is used to perform this analyses. Analytical results obtained are discussed and checked against test data.

Proceedings Article | 22 April 2020 Paper

Numerical validation using finite element to assess the performance of microwave sensor in detecting blade tip displacement

Ali Abdul-Aziz, Samir Mustapha, Khaled Aboumerhi

Proceedings Volume 11382, 1138202 (2020) https://doi.org/10.1117/12.2556194

KEYWORDS: Sensors, Microwave radiation, Finite element methods, Sensor performance, Safety, Data acquisition, Distance measurement, 3D modeling, Structural health monitoring, Denoising

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Gas turbine engine manufacturers are in continuous strive to improve the durability and the technology behind engine development to help monitor engine health and performance. Such technologies are confined to employing highly specialized sensors within the engine compartment. The role of the sensors is to screen and track the structural response of the engine components and in particular the rotor disk due to its venerability to endure failure since it is subject to complex and harsh loading conditions. Detecting unexpected or excessive blade vibration before failure is critical to ensure safety and to achieve projected component life. Nondestructive Evaluation has been the traditional method of detection in addition to relying exclusively on visual inspections as well as other means. These methods require time and cost and do not provide accurate feedback on the health when the engine is in operation. At NASA Glenn Research Center, efforts are undergoing to develop, and test validates microwave-based blade tip timing sensors in support of these concerns and to investigate their application for propulsion health monitoring under the Transformational Tools and Technologies Project (TTTP). A set of prototype sensors is used to assess their ability and applicability in making blade tip clearance measurements in an attempt to extract the blade tip timing from the acquired raw data. The sensors are non-contact type and microwavebased technology. The study covers an experimental task to define the optimum set-up of these sensors, determine their sensitivity in making blade tip deflection measurements and validate their performance against realistic geometries in a spin rig. It also includes finite element analysis base calculations to compare with the experimental data. Data pertaining to the findings obtained from the testing as well as the analytical results are presented and discussed. This work is an extension of a prior combined experimental and computational study that is available in reference [1].

Proceedings Article | 20 March 2019 Presentation + Paper

Propulsion health monitoring assessed by microwave sensor performance and blade tip timing

Ali Abdul-Aziz, Mark Woike, Robert Anderson, Khaled Aboumerhis

Proceedings Volume 10973, 109730Q (2019) https://doi.org/10.1117/12.2515450

KEYWORDS: Sensors, Microwave radiation, Data acquisition, Finite element methods, Electronics, Structural health monitoring, Calibration, Sensor performance, Safety, Distance measurement

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Gas turbine engine makers are always striving to implement newer technologies to help monitor the engine health and performance. Among these technologies is the employment of highly specialized sensors within the engine compartment. The sensors are to screen response of components such as rotor disk blades which are subjects to complex loading conditions and that includes combined thermal and mechanical loads. Detecting unexpected or excessive blade Vibration before failure is critical to ensure safety and to achieve expected apparatus life. Traditional detection methods have relied solely on component inspection during service or on the use of gage telemetry systems as well as other means of non-destructive evaluation. These methods require time and cost and do not provided an accurate feedback of the health when the engine is in operation. At NASA Glenn Research Center, an effort is underway to develop and test validate microwave based blade tip timing sensors in support of the latter concerns and for the purpose of investigating their application for propulsion health monitoring under the Transformational Tools and Technologies Project. This process involves working with prototype sensors to determine their applicability and assess their ability in making blade tip clearance measurements along with further refining a methodology required to extract deflection measurements from the raw data acquired from the sensors. The efforts focus specifically on the use and implementation of microwave based tip-timing sensors that are intended to be used for non-contact stress measurement application. The work includes an experimental task to define the optimum set-up of these sensors, determine their sensitivity in making blade tip deflection measurements and validate their performance against realistic geometries in a spin rig. This also includes analytical calculations to compare to the experimental results. Data pertaining to the findings obtained from the testing as well as the supportive analytical results are presented and discussed.

Proceedings Article | 27 March 2018 Presentation + Paper

Turbofan engine performance study under simulated failure and non-traditional flight conditions

Ali Abdul-Aziz, Robert Bissler, D. Blake Stringer

Proceedings Volume 10601, 1060106 (2018) https://doi.org/10.1117/12.2297144

KEYWORDS: Device simulation, Manufacturing

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Proceedings Article | 19 April 2017 Presentation + Paper

Data collection and analysis software development for rotor dynamics testing in spin laboratory

Ali Abdul-Aziz, Daniel Arble, Mark Woike

Proceedings Volume 10171, 101710L (2017) https://doi.org/10.1117/12.2260115

KEYWORDS: Data acquisition, Sensors, LabVIEW, Analytical research, Inspection, Data modeling, Data processing, Software development, Nondestructive evaluation, Sensor technology

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Proceedings Article | 27 March 2015 Paper

Engine rotor health monitoring: an experimental approach to fault detection and durability assessment

Ali Abdul-Aziz, Mark Woike, Michelle Clem, George Baaklini

Proceedings Volume 9436, 94360A (2015) https://doi.org/10.1117/12.2087602

KEYWORDS: Sensors, Microwave radiation, Safety, Data acquisition, Finite element methods, Manufacturing, Structural health monitoring, Detector development, Sensor technology, 3D modeling

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Efforts to update and improve turbine engine components in meeting flights safety and durability requirements are commitments that engine manufacturers try to continuously fulfill. Most of their concerns and developments energies focus on the rotating components as rotor disks. These components typically undergo rigorous operating conditions and are subject to high centrifugal loadings which subject them to various failure mechanisms. Thus, developing highly advanced health monitoring technology to screen their efficacy and performance is very essential to their prolonged service life and operational success. Nondestructive evaluation techniques are among the many screening methods that presently are being used to pre-detect hidden flaws and mini cracks prior to any appalling events occurrence. Most of these methods or procedures are confined to evaluating material’s discontinuities and other defects that have mature to a point where failure is eminent. Hence, development of more robust techniques to pre-predict faults prior to any catastrophic events in these components is highly vital. This paper is focused on presenting research activities covering the ongoing research efforts at NASA Glenn Research Center (GRC) rotor dynamics laboratory in support of developing a fault detection system for key critical turbine engine components. Data obtained from spin test experiments of a rotor disk that relates to investigating behavior of blade tip clearance, tip timing and shaft displacement based on measured data acquired from sensor devices such as eddy current, capacitive and microwave are presented. Additional results linking test data with finite element modeling to characterize the structural durability of a cracked rotor as it relays to the experimental tests and findings is also presented. An obvious difference in the vibration response is shown between the notched and the baseline no notch rotor disk indicating the presence of some type of irregularity.

Proceedings Article | 27 March 2015 Paper

Assessment of NDE methods for detecting cracks and damage in environmental barrier coated CMC tested under tension

Ali Abdul-Aziz, Adam Wroblewski, Ramakrishna Bhatt, Martha Jaskowiak, Daniel Gorican, Richard Rauser

Proceedings Volume 9436, 943609 (2015) https://doi.org/10.1117/12.2087600

KEYWORDS: Digital image correlation, Coating, Composites, Computed tomography, Optical microscopy, Cameras, Photography, Scanning electron microscopy, Nondestructive evaluation, Silicon carbide

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For validating physics based analytical models predicting spallation life of environmental barrier coating (EBC) on fiber reinforced ceramic matrix composites, the fracture strength of EBC and kinetics of crack growth in EBC layers need to be experimentally determined under engine operating conditions. In this study, a multi layered barium strontium aluminum silicate (BSAS) based EBC-coated, melt infiltrated silicon carbide fiber reinforced silicon carbide matrix composite (MI SiC/SiC) specimen was tensile tested at room temperature. Multiple tests were performed on a single specimen with increasing predetermined stress levels until final failure. During loading, the damage occurring in the EBC was monitored by digital image correlation (DIC). After unloading from the predetermined stress levels, the specimen was examined by optical microscopy and computed tomography (CT). Results indicate both optical microscopy and CT could not resolve the primary or secondary cracks developed during tensile loading until failure. On the other hand, DIC did show formation of a primary crack at ~ 50% of the ultimate tensile strength and this crack grew with increasing stress and eventually led to final failure of the specimen. Although some secondary cracks were seen in the DIC strain plots prior to final failure, the existence of these cracks were not confirmed by other methods. By using a higher resolution camera, it is possible to improve the capability of DIC in resolving secondary cracks and damage in coated specimen tested at room temperature, but use of DIC at high temperature requires significant development. Based on the current data, it appears that both optical microscopy and CT do not offer any hope for detecting crack initiation or determining crack growth in EBC coated CMC tested at room or high temperatures after the specimen has been unloaded. Other methods such as, thermography and optical/SEM of the polished cross section of EBC coated CMC specimens stressed to predetermined levels and cycled to certain time at a given stress need to be explored.

Proceedings Article | 17 April 2014 Paper

Turbine engine rotor health monitoring evaluation by means of finite element analyses and spin tests data

Ali Abdul-Aziz, Mark Woike, Michelle Clem, George Baaklini

Proceedings Volume 9062, 90620M (2014) https://doi.org/10.1117/12.2046373

KEYWORDS: Sensors, Finite element methods, Analytical research, Data modeling, Safety, Microwave radiation, 3D modeling, Failure analysis, Sensor technology, Nondestructive evaluation

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Proceedings Article | 10 April 2014 Paper

Progress of a cross-correlation based optical strain measurement technique for detecting radial growth on a rotating disk

Michelle Clem, Mark Woike, Ali Abdul-Aziz

Proceedings Volume 9062, 90620N (2014) https://doi.org/10.1117/12.2044718

KEYWORDS: Particles, Optical testing, Image processing, Imaging systems, Thermography, Error analysis, Cameras, In situ metrology, Sensors, Aluminum

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The Aeronautical Sciences Project under NASA’s Fundamental Aeronautics Program is interested in the development of novel measurement technologies, such as optical surface measurements for the in situ health monitoring of critical constituents of the internal flow path. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. The present study, aims to further validate and develop an optical strain measurement technique to measure the radial growth and strain field of an already cracked disk, mimicking the geometry of a sub-scale turbine engine disk, under loaded conditions in the NASA Glenn Research Center’s High Precision Rotordynamics Laboratory. The technique offers potential fault detection by imaging an applied high-contrast random speckle pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds (loaded conditions) induces an external load, resulting in a radial growth of the disk of approximately 50.0-μm in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be ‘shifted’. The resulting particle displacements between the two images is measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. A random particle distribution is adhered onto the surface of the cracked disk and two bench top experiments are carried out to evaluate the technique’s ability to measure the induced particle displacements. The disk is shifted manually using a translation stage equipped with a fine micrometer and a hotplate is used to induce thermal growth of the disk, causing the particles to become shifted. For both experiments, reference and test images are acquired before and after the induced shifts, respectively, and then processed using PIV software. The controlled manual translation of the disk resulted in detection of the particle displacements accurate to ~1.75% of full scale and the thermal expansion experiment resulted in successful detection of the disk’s thermal growth as compared to the calculated thermal expansion results. After validation of the technique through the induced shift experiments, the technique is implemented in the Rotordynamics Lab for preliminary assessment in a simulated engine environment. The discussion of the findings and plans for future work to improve upon the results are addressed in the paper.

Proceedings Article | 10 April 2014 Paper

Structural health monitoring on turbine engines using microwave blade tip clearance sensors

Mark Woike, Ali Abdul-Aziz, Michelle Clem

Proceedings Volume 9062, 90620L (2014) https://doi.org/10.1117/12.2044967

KEYWORDS: Sensors, Microwave radiation, Fluctuations and noise, Neodymium, Structural health monitoring, Sensor technology, Temperature metrology, Vibrometry, Nickel, Safety

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Proceedings Article | 31 March 2014 Paper

Test validation of environmental barrier coating (EBC) durability and damage tolerance modeling approach

Ali Abdul-Aziz, Ali Najafi, Frank Abdi, Ramakrishna Bhatt, Joseph Grady

Proceedings Volume 9058, 90580P (2014) https://doi.org/10.1117/12.2045914

KEYWORDS: Coating, Failure analysis, Thin film coatings, Finite element methods, Composites, 3D modeling, Tolerancing, Plasma, Silicon, Ceramics

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Proceedings Article | 11 April 2013 Paper

Environmental barrier coating (EBC) durability modeling using a progressive failure analysis approach part II

Ali Abdul-Aziz, Joseph Arias, Frank Abdi, Ramakrishna Bhatt, Joseph Grady, D. Zhu

Proceedings Volume 8693, 86930G (2013) https://doi.org/10.1117/12.2008490

KEYWORDS: Coating, Failure analysis, Thin film coatings, Finite element methods, Composites, Mechanics, Reverse modeling, Silicon carbide, Interfaces, Reverse engineering

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The need for a protecting guard for the popular Ceramic Matrix Composites (CMCs) is getting a lot of attention from engine manufacturers and aerospace companies. This is because the CMC has a weight advantage over standard metallic materials and more performance benefits. They are also commonly porous material and this feature is somewhat beneficial since it allows some desirable infiltration. They further undergo degradation that typically includes coating interface oxidation as opposed to moisture induced matrix which is generally seen at a higher temperature. Variety of factors such as residual stresses, coating process related flaws, and casting conditions may influence the degradation of mechanical properties of CMC. The cause of such defects which cause cracking and other damage is that not much energy is absorbed during fracture of these materials. Therefore, an understanding of the issues that control crack deflection and propagation along interfaces is needed to maximize the energy dissipation capabilities of layered ceramics. These durability considerations are being addressed by introducing highly specialized form of environmental barrier coating (EBC) that is being developed and explored in particular for high temperature applications greater than 1100 °C ^1-3. The EBCs are typically a multilayer of coatings and are in the order of hundreds of microns thick. Thus, evaluating components and subcomponents made out of CMCs under gas turbine engine conditions are suggested to demonstrate that these materials will perform as required especially when subjected to extreme temperatures and harsh operating environment. The need exists to use advanced computational methods to assess risk associated with exposure to high temperature of EBC coated CMC specimens. In the work presented here, multiscale progressive failure analysis (PFA) approach was used to evaluate the damage growth in the coating and CMC after exposure time to cyclic and elevated temperatures. In each cycle, the specimen was heated to 1300 °C then maintained at that temperature for a period of time before cooling it down to room temperature. The PFA evaluation was carried out with the GENOA⁴ software using integrated capability inclusive of: finite element structural analysis, micro-mechanics, damage progression and tracking, fracture mechanics, and life prediction. In this paper, reverse engineered constituent properties obtained from CMC lamina properties were used as input to PFA to evaluate the degradation of specimen strength during thermal cycling. The analysis results indicated that the damage initiated in the top coat of the EBC then propagated down to the bond before reaching the CMC. Life assessment of the CMC was carried out twice, once using micromechanics properties as input and another time using macromechanics properties. It was determined that the use macromechanics properties yielded a more conservative life prediction for the CMC specimen as compared to that obtained from the use of micromechanics with fiber and matrix properties as input. Residual stresses evaluated during cooldown supported the onset of damage in the top coat. All stages of damage evolution were captured with PFA including damage initiation and damage propagation. Details on the life prediction of EBC and CMC materials are discussed next.

Proceedings Article | 11 April 2013 Paper

Turbine engine rotor health monitoring and durability evaluation using spin tests data

Ali Abdul-Aziz, Mark Woike, Michelle Clem, George Baaklini

Proceedings Volume 8693, 86930N (2013) https://doi.org/10.1117/12.2008978

KEYWORDS: Sensors, Analytical research, Safety, Nondestructive evaluation, Manufacturing, Data modeling, Sensor technology, Inspection, Mathematical modeling, Product engineering

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Proceedings Article | 11 April 2013 Paper

Investigation of a cross-correlation based optical strain measurement technique for detecting radial growth on a rotating disk

Michelle Clem, Mark Woike, Ali Abdul-Aziz

Proceedings Volume 8693, 86930O (2013) https://doi.org/10.1117/12.2012266

KEYWORDS: Particles, Glasses, Adhesives, Reflectivity, Optical testing, Aluminum, Image processing, Sensors, Speckle pattern, Error analysis

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The Aeronautical Sciences Project under NASA’s Fundamental Aeronautics Program is extremely interested in the development of novel measurement technologies, such as optical surface measurements in the internal parts of a flow path, for in situ health monitoring of gas turbine engines. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. In the present study, a cross-correlation imaging technique is investigated in a proof-of-concept study as a possible optical technique to measure the radial growth and strain field on an already cracked sub-scale turbine engine disk under loaded conditions in the NASA Glenn Research Center’s High Precision Rotordynamics Laboratory. The optical strain measurement technique under investigation offers potential fault detection using an applied high-contrast random speckle pattern and imaging the pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds induces an external load, resulting in a radial growth of the disk of approximately 50.0-μm in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be ‘shifted’. The resulting particle displacements between the two images will then be measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. In order to develop and validate this optical strain measurement technique an initial proof-of-concept experiment is carried out in a controlled environment. Using PIV optimization principles and guidelines, three potential speckle patterns, for future use on the rotating disk, are developed and investigated in the controlled experiment. A range of known shifts are induced on the patterns; reference and data images are acquired before and after the induced shift, respectively, and the images are processed using the crosscorrelation algorithms in order to determine the particle displacements. The effectiveness of each pattern at resolving the known shift is evaluated and discussed in order to choose the most suitable pattern to be implemented onto a rotating disk in the Rotordynamics Lab. Although testing on the rotating disk has not yet been performed, the driving principles behind the development of the present optical technique are based upon critical aspects of the future experiment, such as the amount of expected radial growth, disk analysis, and experimental design and are therefore addressed in the paper.

Proceedings Article | 11 April 2013 Paper

Optical strain and crack-detection measurements on a rotating disk

Mark Woike, Ali Abdul-Aziz, Michelle Clem, Gustave Fralick

Proceedings Volume 8693, 86930M (2013) https://doi.org/10.1117/12.2012264

KEYWORDS: Sensors, Data acquisition, Distributed interactive simulations, Neodymium, Composites, Aluminum, Ions, Chromium, Image processing, Image sensors

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The development of techniques for the in-situ measurement and structural health monitoring of the rotating components in gas turbine engines is of major interest to NASA. As part of this on-going effort, several experiments have been undertaken to develop methods for detecting cracks and measuring strain on rotating turbine engine like disks. Previous methods investigated have included the use of blade tip clearance sensors to detect the presence of cracks by monitoring the change in measured blade tip clearance and analyzing the combined disk-rotor system’s vibration response. More recently, an experiment utilizing a novel optical Moiré based concept has been conducted on a subscale turbine engine disk to demonstrate a potential strain measurement and crack detection technique. Moiré patterns result from the overlap of two repetitive patterns with slightly different spacing. When this technique is applied to a rotating disk, it has the potential to allow for the detection of very small changes in spacing and radial growth in a rotating disk due to a flaw such as a crack. This investigation was a continuation of previous efforts undertaken in 2011-2012 to validate this optical concept. The initial demonstration attempted on a subscale turbine engine disk was inconclusive due to the minimal radial growth experienced by the disk during operation. For the present experiment a new subscale Aluminum disk was fabricated and improvements were made to the experimental setup to better demonstrate the technique. A circular reference pattern was laser etched onto a subscale engine disk and the disk was operated at speeds up to 12 000 rpm as a means of optically monitoring the Moiré created by the shift in patterns created by the radial growth due the presence of the simulated crack. Testing was first accomplished on a clean defect free disk as a means of acquiring baseline reference data. A notch was then machined in to the disk to simulate a crack and testing was repeated for the purposes of demonstrating the concept. Displacement data was acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the optical data and for validating other sensor based crack detection techniques.

Proceedings Article | 30 March 2012 Paper

Turbine engine disk rotor health monitoring assessment using spin tests data

Ali Abdul-Aziz, Mark Woike, George Baaklini, James Bodis

Proceedings Volume 8346, 834616 (2012) https://doi.org/10.1117/12.912524

KEYWORDS: Sensors, Microwave radiation, Electronics, Sensor technology, Safety, Nondestructive evaluation, Structural health monitoring, Capacitance, Distance measurement, Environmental sensing

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Proceedings Article | 30 March 2012 Paper

Environmental barrier coating (EBC) durability modeling using a progressive failure analysis approach

Ali Abdul-Aziz, Galib Abumeri, William Troha, Ramakrishna Bhatt, Joseph Grady, D. Zhu

Proceedings Volume 8346, 834612 (2012) https://doi.org/10.1117/12.912865

KEYWORDS: Coating, Failure analysis, Finite element methods, Composites, Thin film coatings, Interfaces, Mechanics, Ceramics, Plasma, 3D modeling

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Ceramic matrix composites (CMCs) are getting the attention of most engine manufacturers and aerospace firms for turbine engine and other related applications. This is because of their potential weight advantage and performance benefits. As a protecting guard for these materials, a highly specialized form of environmental barrier coating (EBC) is being developed and explored for high temperature applications that are greater than 1100 °C^1,2. The EBCs are typically a multilayer of coatings and are on the order of hundreds of microns thick. CMCs are generally porous materials and this feature is somewhat beneficial since it allows some desirable infiltration of the EBC. Their degradation usually includes coating interface oxidation as opposed to moisture induced matrix degradation which is generally seen at a higher temperature. A variety of factors such as residual stresses, coating process related flaws, and casting conditions may influence the strength of degradation. The cause of such defects which cause cracking and other damage is that not much energy is absorbed during fracture of these materials. Therefore, an understanding of the issues that control crack deflection and propagation along interfaces is needed to maximize the energy dissipation capabilities of layered ceramics. Thus, evaluating components and subcomponents made out of CMCs under gas turbine engine conditions is suggested to demonstrate that these material will perform as expected and required under these aggressive environmental circumstances. Progressive failure analysis (PFA) is applied to assess the damage growth of the coating under combined thermal and mechanical loading conditions. The PFA evaluation is carried out using a full-scale finite element model to account for the average material failure at the microscopic or macroscopic levels. The PFA life prediction evaluation identified the root cause for damage initiation and propagation. It indicated that delamination type damage initiated mainly in the bond and intermediate coating materials then propagated to the substrate. Results related to damage initiation and propagation; behavior and life assessment of the coating at the interface of the EBC/CMC are presented and discussed.

Proceedings Article | 30 March 2012 Paper

Investigation of a moiré based crack detection technique for propulsion health monitoring

Mark Woike, Ali Abdul-Aziz, Gustave Fralick, John Wrbanek

Proceedings Volume 8346, 834615 (2012) https://doi.org/10.1117/12.914836

KEYWORDS: Sensors, Data acquisition, Image processing, Composites, Light emitting diodes, Safety, Image acquisition, Image registration, Image analysis, Microwave radiation

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Proceedings Article | 9 April 2010 Paper

Propulsion health monitoring of a turbine engine disk using spin test data

Ali Abdul-Aziz, Mark Woike, Nikunj Oza, Bryan Matthews, George Baakilini

Proceedings Volume 7650, 76501B (2010) https://doi.org/10.1117/12.847574

KEYWORDS: Sensors, Data modeling, Detection and tracking algorithms, Sensor technology, Safety, Analytical research, Nondestructive evaluation, Inspection, Capacitance, Environmental monitoring

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On line detection techniques to monitor the health of rotating engine components are becoming increasingly attractive options to aircraft engine companies in order to increase safety of operation and lower maintenance costs. Health monitoring remains a challenging feature to easily implement, especially, in the presence of scattered loading conditions, crack size, component geometry and materials properties. The current trend, however, is to utilize noninvasive types of health monitoring or nondestructive techniques to detect hidden flaws and mini cracks before any catastrophic event occurs. These techniques go further to evaluate materials' discontinuities and other anomalies that have grown to the level of critical defects which can lead to failure. Generally, health monitoring is highly dependent on sensor systems that are capable of performing in various engine environmental conditions and able to transmit a signal upon a predetermined crack length, while acting in a neutral form upon the overall performance of the engine system. Efforts are under way at NASA Glenn Research Center through support of the Intelligent Vehicle Health Management Project (IVHM) to develop and implement such sensor technology for a wide variety of applications. These efforts are focused on developing high temperature, wireless, low cost and durable products. Therefore, in an effort to address the technical issues concerning health monitoring of a rotor disk, this paper considers data collected from an experimental study using high frequency capacitive sensor technology to capture blade tip clearance and tip timing measurements in a rotating engine-like-disk-to predict the disk faults and assess its structural integrity. The experimental results collected at a range of rotational speeds from tests conducted at the NASA Glenn Research Center's Rotordynamics Laboratory will be evaluated using multiple data-driven anomaly detection techniques to identify anomalies in the disk. This study is expected to present a select evaluation of online health monitoring of a rotating disk using these high caliber sensors and test the capability of the in-house spin system.

Proceedings Article | 8 April 2009 Paper

NDE using sensor based approach to propulsion health monitoring of a turbine engine disk

Ali Abdul-Aziz, Mark Woike, G. Abumeri, John Lekki, George Baaklini

Proceedings Volume 7295, 729505 (2009) https://doi.org/10.1117/12.815494

KEYWORDS: Failure analysis, Nondestructive evaluation, Sensors, Finite element methods, Safety, Mechanics, Data modeling, Inspection, Analytical research, Image filtering

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Proceedings Article | 4 April 2008 Paper

Structural evaluation of a nickel base super alloy metal foam via NDE and finite element

Ali Abdul-Aziz, G. Abumeri, Mohit Garg, P. Young

Proceedings Volume 6929, 69291J (2008) https://doi.org/10.1117/12.776343

KEYWORDS: Foam, Metals, 3D modeling, Solids, Finite element methods, Computed tomography, Failure analysis, Nondestructive evaluation, 3D image processing, Composites

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Proceedings Article | 26 April 2007 Paper

A combined NDE/FEA approach to evaluate the structural response of a metal foam

Louis Ghosn, Ali Abdul-Aziz, Sai Raj, Richard Rauser

Proceedings Volume 6526, 65262U (2007) https://doi.org/10.1117/12.715215

KEYWORDS: Foam, Metals, 3D modeling, Finite element methods, Solids, 3D image processing, Computed tomography, X-ray computed tomography, Aerospace engineering, Nondestructive evaluation

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Metal foams are expected to find use in structural applications where weight is of particular concern, such as space vehicles, rotorcraft blades, car bodies or portable electronic devices. The obvious structural application of metal foam is for light weight sandwich panels, made up of thin solid face sheets and a metallic foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by a light weight metal foam core. The resulting high-stiffness structure is lighter than that constructed only out of the solid metal material. Since the face sheets carry the applied in-plane and bending loads, the sandwich architecture is a viable engineering concept. However, the metal foam core must resist transverse shear loads and compressive loads while remaining integral with the face sheets. Challenges relating to the fabrication and testing of these metal foam panels remain due to some mechanical properties falling short of their theoretical potential. Theoretical mechanical properties are based on an idealized foam microstructure and assumed cell geometry. But the actual testing is performed on as fabricated foam microstructure. Hence in this study, a detailed three dimensional foam structure is generated using series of 2D Computer Tomography (CT) scans. The series of the 2D images are assembled to construct a high precision solid model capturing all the fine details within the metal foam as detected by the CT scanning technique. Moreover, a finite element analysis is then performed on as fabricated metal foam microstructures, to calculate the foam mechanical properties with the idealized theory. The metal foam material is an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. Tensile and compressive mechanical properties are deduced from the FEA model and compared with the theoretical values for three different foam densities. The combined NDE/FEA provided insight in the variability of the mechanical properties compared to idealized theory.

Proceedings Article | 29 March 2006 Paper

Finite element design study of a bladed flat rotating disk to simulate cracking in a typical turbine disk: Part II

Ali Abdul-Aziz, Jeffrey Trudell, George Baakilini

Proceedings Volume 6176, 61760J (2006) https://doi.org/10.1117/12.649802

KEYWORDS: Safety, Curium, Finite element methods, Nondestructive evaluation, Sensors, Damage detection, Reliability, Sensing systems, Aerospace engineering, Nickel

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Proceedings Article | 29 March 2006 Paper

On the material characterization of a composite using micro CT image based finite element modeling

A. Abdul Aziz, C. Saury, V. Bui Xuan, P. Young

Proceedings Volume 6176, 617605 (2006) https://doi.org/10.1117/12.667766

KEYWORDS: 3D modeling, Composites, Computed tomography, Finite element methods, 3D image processing, X-ray computed tomography, Ceramics, Image segmentation, Image processing, Image filtering

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Novel techniques for generating robust and accurate meshes based on 3-D imaging data have recently been developed which make the prediction of macro-structural properties of composite structures based on micro-structural composition straightforward. The accuracy of reconstructions is a particular strong point of these new techniques with geometric accuracy only contingent on image quality. Algorithms developed and used are topology preserving, volume preserving and multi-part geometric models can be handled straightforwardly. In addition to modeling different constituent materials as separate mesh domains, material properties can be assigned based on signal strength in the parent image thereby providing a way of modeling continuous variations in properties for an inhomogeneous medium. These new techniques have been applied to the analysis of a ceramic matrix composite which was micro-CT scanned and the influence of imaging parameters on both predicted bulk properties and localized stresses has been explored. This paper utilizes the Computed Tomography (CT) as the NDE technique to characterize the initial matrix porosity's locations and sizes in a Ceramic Matrix Composites (CMC) test specimen. Further, the Finite Element (FE) method is applied to calculate the localized stress field around these pores based on the geometric modeling of the specimen's CT results, using image analysis, geometric modeling and meshing software, ScanIP/ScanFE [1]. The analyses will simulate experimental loading conditions where scanned specimens are then tensile tested to a 0.07 % total strain to identify the matrix cracking locations in relation to the original pores. Additional work is carried out combining the image processing and finite element to investigate the applicability of some novel meshing techniques. Finally, the calculated Finite Element [2-4] localized stress risers are compared with the observed matrix cracking locations. This work is expected to show that an FE model based on an accurate 3-D rendered model from a series of CT slices is an essential tool to quantify the effects of internal macroscopic defects of complex material systems such as CMCs.

Proceedings Article | 29 March 2006 Paper

Cruciform specimen design for testing advanced aeropropulsion materials under cyclic in-plane biaxial loading

Ali Abdul-Aziz, David Krause

Proceedings Volume 6176, 617609 (2006) https://doi.org/10.1117/12.649804

KEYWORDS: Finite element methods, Stress analysis, Aerospace engineering, Analytical research, Fabrication, Radioisotopes, Nickel, Composites, Roads, Manufacturing

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Proceedings Article | 29 March 2006 Paper

Combined experimental and analytical study using cruciform specimen for testing advanced aeropropulsion materials under in-plane biaxial loading

Ali Abdul-Aziz, David Krause

Proceedings Volume 6176, 61761K (2006) https://doi.org/10.1117/12.649810

KEYWORDS: Finite element methods, Analytical research, Data modeling, Head, Failure analysis, Calibration, Composites, Radioisotopes, Aerospace engineering, Roads

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Proceedings Article | 19 May 2005 Paper

Finite element design study of a bladed, flat rotating disk to simulate cracking in a typical turbine disk

Ali Abdul-Aziz, Jeffrey Trudell, George Baaklini

Proceedings Volume 5767, (2005) https://doi.org/10.1117/12.601896

KEYWORDS: Nondestructive evaluation, Safety, Finite element methods, Chemical elements, Sensing systems, Signal detection, Inspection, Aerospace engineering, Nickel, Sensors

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Proceedings Article | 19 May 2005 Paper

Structural assessment of metal foam using combined NDE and FEA

Louis Ghosn, Ali Abdul-Aziz, Philippe Young, Richard Rauser

Proceedings Volume 5767, (2005) https://doi.org/10.1117/12.601753

KEYWORDS: Foam, Metals, 3D modeling, Finite element methods, Solids, 3D image processing, Nondestructive evaluation, Computed tomography, X-ray computed tomography, Aerospace engineering

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Proceedings Article | 20 July 2004 Paper

A combined NDE-fatigue testing and three-dimensional image processing study of a SiC/SiC composite system

Ali Abdul-Aziz, Louis Ghosn, George Baaklini, Richard Rauser, John Zima

Proceedings Volume 5393, (2004) https://doi.org/10.1117/12.538241

KEYWORDS: Composites, Computed tomography, Nondestructive evaluation, 3D image processing, Image processing, Silicon carbide, 3D modeling, X-ray computed tomography, Ceramics, Coating

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Non destructive evaluation (NDE) is a critical technology for improving the quality of a component in a cost-sparing production environment. NDE detects variations in a material or a component without altering or damaging the test piece. Using these techniques to improve the production process requires characterization of the faults and their influence on the component performance. This task depends on the material properties and on the complexity of the component geometry. Hence, the NDE technique is applied to study the structural durability of ceramic matrix composite materials used in gas turbine engine applications. Matrix voids are common anomalies generated during the melt infiltration process. The effects of these matrix porosities are usually associated with a reduction in the initial overall composite stiffness and an increase in the thermal conductivity of the component. Furthermore, since the role of the matrix as well as the coating is to protect the fibers from the harsh engine environments, the current design approach is to limit the design stress level of CMC components to always be below the first matrix cracking stress. In this study, the effect of matrix porosity on the matrix cracking stress is evaluated using a combined fatigue tensile testing, NDE, and 3 D image processing approach. Computed Tomography (CT) is utilized as the NDE technique to characterize the initial matrix porosity’s locations and sizes in various CMC test specimens. The three dimensional volume rendering approach is exercised to construct the 3 D volume of the specimen based on the geometric modeling of the specimen's CT results using image analysis and geometric modeling software. The same scanned specimens are then fatigue tested to various maximum loads and temperatures to depict the matrix cracking locations in relation to the initial damage. The specimen are then re-scanned and checked for further anomalies and obvious changes in the damage state. Finally, rendered volumes of the gauge region of the specimen is generated and observed to check damage progression with increasing cycles. Observations and critical findings related to this material are reported.

Proceedings Article | 1 August 2003 Paper

Combined NDE/finite element technique to study the effects of matrix porosity in the behavior of ceramic matrix composites

Ali Abdul-Aziz, Louis Ghosn, George Baaklini, Ramakrishna Bhatt

Proceedings Volume 5046, (2003) https://doi.org/10.1117/12.484775

KEYWORDS: Computed tomography, 3D modeling, Finite element methods, Composites, Ceramics, 3D image processing, Nondestructive evaluation, Coating, X-ray computed tomography, Roads

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Proceedings Article | 18 June 2002 Paper

Nondestructive evaluation of ceramic matrix composites coupled with finite element analyses

Ali Abdul-Aziz, George Baaklini, Ramakrishna Bhatt

Proceedings Volume 4704, (2002) https://doi.org/10.1117/12.470733

KEYWORDS: 3D modeling, Computed tomography, Finite element methods, 3D image processing, Nondestructive evaluation, Solid modeling, Composites, Ceramics, Failure analysis, Data modeling

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Proceedings Article | 3 August 2001 Paper

Integrated NDE and FEM characterization of composite rotors

Ali Abdul-Aziz, George Baaklini, Jeffrey Trudell

Proceedings Volume 4336, (2001) https://doi.org/10.1117/12.435574

KEYWORDS: Finite element methods, Nondestructive evaluation, Composites, Mechanics, Computed tomography, Chemical elements, 3D modeling, Solids, Stress analysis, Structural analysis

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Proceedings Article | 13 May 2000 Paper

Challenges in integrating nondestructive evaluation and finite-element methods for realistic structural analysis

Ali Abdul-Aziz, George Baaklini, Dmitri Zagidulin, Richard Rauser

Proceedings Volume 3993, (2000) https://doi.org/10.1117/12.385504

KEYWORDS: 3D modeling, Computed tomography, Finite element methods, Nondestructive evaluation, Composites, 3D image processing, Image filtering, Metals, Image processing, Solid modeling

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Showing 5 of 35 publications

Conference Committee Involvement (15)

NDE 4.0, Predictive Maintenance, Communication, and Energy Systems: The Digital Transformation of NDE III

17 March 2025 | Vancouver, Canada

NDE 4.0, Predictive Maintenance, Communication, and Energy Systems: The Digital Transformation of NDE II

25 March 2024 | Long Beach, California, United States

NDE 4.0, Predictive Maintenance, Communication, and Energy Systems: The Digital Transformation of NDE

14 March 2023 | Long Beach, California, United States

NDE 4.0, Predictive Maintenance, and Communication and Energy Systems in a Globally Networked World

8 March 2022 | Long Beach, California, United States

NDE 4.0 and Smart Structures for Industry, Smart Cities, Communication, and Energy

8 March 2021 | Online Only, California, United States

Smart Structures and NDE for Industry 4.0, Smart Cities, and Energy Systems

27 April 2020 | Online Only, California, United States

Smart Structures and NDE for Energy Systems and Industry 4.0

4 March 2019 | Denver, Colorado, United States

Smart Materials and Nondestructive Evaluation for Energy Systems IV

5 March 2018 | Denver, Colorado, United States

Smart Materials and Nondestructive Evaluation for Energy Systems III

27 March 2017 | Portland, Oregon, United States

Smart Materials and Nondestructive Evaluation for Energy Systems II

21 March 2016 | Las Vegas, Nevada, United States

Smart Materials and Nondestructive Evaluation for Energy Systems

9 March 2015 | San Diego, California, United States

Nondestructive Evaluation and Health Monitoring of Aerospace Materials, Composites, and Civil Infrastructure V

28 February 2006 | San Diego, CA, United States

Nondestructive Evaluation and Health Monitoring of Aerospace Materials, Composites, and Civil Infrastructure IV

8 March 2005 | San Diego, CA, United States

Nondestructive Evaluation and Health Monitoring of Aerospace Materials and Composites III

16 March 2004 | San Diego, CA, United States

Nondestructive Evaluation and Health Monitoring of Aerospace Materials and Composites

3 March 2003 | San Diego, California, United States

Showing 5 of 15 Conference Committees

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