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Kirikera, Goutham RaghavendraA Structural Neural System for Health Monitoring of Structures
PhD, University of Cincinnati, 2006, Engineering : Mechanical Engineering

A method for structural health monitoring of large structures based on detecting acoustic emissions produced by damage was developed for this dissertation. The advantage of sensing acoustic emissions is that small damage can be detected in structures built with complex geometry and anisotropic materials. A longstanding limitation of the acoustic emission method is that a large number of bulky sensors are required to monitor cracks that can form at any location on a complex structure. The sensors and data acquisition system are also required to work at a high sampling rate because the frequencies of acoustic waves propagating in the structure due to damage are on the order of hundreds of kHz. To overcome the difficulties with using the acoustic emission method, a very elegant and powerful technique that many researchers have either missed or avoided is presented in this dissertation. The new sensing technique is called a structural neural system. The technique was difficult to develop, and required using electronic circuits to mimic the architecture of the biological neural system. In developing the technique, it was also necessary to recognize the strong linkage between fracture mechanics and fatigue damage detection.

The structural neural system developed uses continuous (multi-node) sensors to mimic dendrites, receptors, and the axon which perform sensing in the biological neural system. Analog electronics were then developed to mimic the thresholding and firing functions of the soma (cell body) in the neural system. The end result is a structural neural system that tremendously reduces the complexity and number of data acquisition channels needed to monitor acoustic emissions and detect damage in structures that have high feature density. Simulation and laboratory testing of a prototype of the structural neural system showed that the structural neural system is sensitive to small damage and practical to use on large structures. A field test was also performed in which a simple two-channel four neuron prototype structural neural system was installed on a 9 meter long wind turbine blade at the National Renewable Energy Laboratory in Golden, Colorado. The blade was loaded to failure in a quasi-static proof test. The structural neural system, using only two channels of data acquisition, identified where damage started during the testing, and monitored the growth of damage at five locations on the blade. The structural neural system detected damage well before final failure of the blade, whereas strain gages on the blade did not indicate damage until just before final failure. A post-failure sectioning and examination of the blade verified the damage locations predicted by the structural neural system, and showed that the structural neural system is a practical technique for health monitoring of large structures. Beyond health monitoring, the structural neural system can tell where damage initiates and how damage propagates in a structure. This information might be useful to improve the design and manufacturing of structures.

Committee:

Mark Schulz (Advisor)

Subjects:

Engineering, Mechanical

Keywords:

Acoustic Emission; Structural Health Monitoring; Structural Neural System; Continuous Health Monitoring.

Seyedianchoobi, RasaLong Term Health Monitoring of Anthony Wayne Bridge Main Cable with Acoustic Emission Technique
Master of Science, University of Toledo, 2013, Civil Engineering
The acoustic emission (AE) technique, based on the sudden release of energy within a material generating transient elastic wave propagation, is widely used as a non-destructive technique (NDT). AE events generate a spectrum of stress waves starting at 0 Hz, and typically falling off at several MHz . Based on the characteristics of AE waveforms and wave propagation theory, useful information like source location and the cause of emissions can be obtained. During the course of this research, the background and concepts of AE were studied and utilized. The AE wire breaking detection system on the main cables of the Anthony Wayne Bridge is used as a research laboratory for this thesis. The acoustic emission (AE) method for nondestructive evaluation of main cables of the Anthony Wayne Bridge predicts the location of future invasive inspection and also is able to prevent disastrous failure of the structure. It will be relatively easy, in comparison with periodic physical inspection, to set up an effective long term high resolution health monitoring system for the main cables of the bridge. This study investigated the development of the AE monitoring system and the application of AE to detect wire breaks. The corrosion of metals involves ion transfer between anode and cathode. Electrochemical reactions consist of oxidation and reduction. The oxidation occurs at the anode (releasing electrons to the electrolyte); the reduction, at the cathode. There are several type of corrosion namely pitting, uniform, stress-cracking, and a combination of them. AE can be used to evaluate and predict damages due to corrosion. Then the applicability of an existing AE system on the bridge for detecting corrosion was explored, including both a field test and laboratory testing. A corrosion test was carried out on a piece of aluminum bar with active pitting corrosion to capture the signature of AE waveforms due to corrosion such as amplitude, intensity of acoustic activity and frequency spectrum. The results of this laboratory test help to filter AE waves from the corrosion source.

Committee:

Dr. Douglas Nims, PhD (Committee Chair); Dr. Brian Randolph, PhD (Committee Member); Dr. Ahalapitya Jayatissa, PhD (Committee Member)

Subjects:

Civil Engineering

Keywords:

Acoustic Emission; NDT; Nondestructive; Health Monitoring; Sensors; AE

Nisal, Tejas VMonitoring of Surface Grinding process using Acoustic Emission (AE) with emphasis on Cutting Fluid selection
Master of Science, University of Toledo, 2014, Industrial Engineering
Correct selection of cutting fluid is an important step in all machining operations. In this study, experiments were designed and conducted on AISI 52100 steel to determine the effects of using different cutting fluids in Surface Grinding. The grinding parameters varied were wheel speed, feed, depth of cut and type of cutting fluid. The grinding responses studied here were Acoustic Emission (AE) Signals, Normal and Tangential Forces on the workpiece surface, Grinding Temperature and Surface Roughness. Potential of Acoustic Emission technique as a tool to provide efficient real-time knowledge and monitoring of the grinding process, is tested in this research. AERMS values were used to analyses the process characteristics. This paper proposes four different statistical models for predicting Grinding Temperature, Force, Acoustic Emission (AERMS) and Roughness, based on grinding parameters. This research concludes that the selection of Cutting Fluids influence the Surface finish, AE signals, Temperature and grinding Forces measured. Further, prediction of surface roughness during the grinding process using AE signal monitoring is demonstrated in this work.

Committee:

Ioan Marinescu, Dr. (Advisor); Efstratios Nikolaidis, Dr. (Committee Member); Franchetti Matthew, Dr. (Committee Member)

Subjects:

Industrial Engineering; Mechanical Engineering; Technology

Keywords:

Monitoring; Surface grinding; Cutting fluid selection; Acoustic Emission; Grinding force

Almansour, Amjad Saleh AliUSE OF SINGLE TOW CERAMIC MATRIX MINICOMPOSITES TO DETERMINE FUNDAMENTAL ROOM AND ELEVATED TEMPERATURE PROPERTIES
Doctor of Philosophy, University of Akron, 2017, Mechanical Engineering
The room and high temperature mechanical properties of continuous ceramic fiber reinforced matrix composites makes them attractive for implementation in aerospace and nuclear applications. However, the effect of fiber content has not been addressed in previous work. Therefore, single tow composites with fiber content ranging from 3 to 47 % was studied. Single fiber tow minicomposite is the basic architectural feature of woven and laminate ceramic matrix composites (CMCs). An in depth understanding of the initiation and evolution of damage in various ceramic fiber reinforced minicomposites with different fiber volume fractions and interphases was investigated employing several non-destructive evaluation techniques. A new technique is used to determine matrix crack content based on a damage parameter derived from speed of sound measurements which is compared with the established method using cumulative energy of Acoustic Emission (AE) events. Also, a modified theoretical model was implemented to obtain matrix stress at the onset of matrix cracking. Room temperature tensile, high temperature creep rupture and high temperature oxidation degradation loading conditions were all considered and composites’ constituents were characterized. Moreover, fibers/matrix load sharing was modeled in creep and fiber volume fraction effect on load transfer was investigated using derived theoretical models. Fibers and matrix creep parameters, load transfer model results and numerical model methodology were used to construct minicomposites’ creep strain model to predict creep damage of the different fiber type and content minicomposites. Furthermore, different fiber volume fractions ceramic matrix minicomposites’ electrical resistivity temperature dependence isn’t well understood. Therefore, the influence of fiber content, heat treatment cycles and creep on electrical resistivity measurements of SiC/SiC minicomposites were also studied here. Next, minicomposites’ testing and characterization methodology was used to screen and characterize slurry-derived mullite bond coated minicomposites for enhanced oxidation and creep resistance. Finally, this study shows valuable testing methodologies and models approach for use in screening, developing and improving new generation ceramic matrix composites.

Committee:

Gregory Morscher, Dr (Advisor); Tirumalai Srivatsan, Dr (Committee Member); Craig Menzemer, Dr (Committee Member); Alper Buldum, Dr (Committee Member); Kwek Tze Tan, Dr (Committee Member); Robert Goldberg, Dr (Committee Member); Manigandan Kannan, Dr (Committee Member)

Subjects:

Acoustics; Aerospace Engineering; Aerospace Materials; Chemical Engineering; Chemistry; Electrical Engineering; Engineering; Experiments; High Temperature Physics; Materials Science; Mathematics; Mechanical Engineering; Mechanics; Metallurgy; Theoretical Mathematics; Theoretical Physics

Keywords:

Minicomposites,CMCs,Velocity of Sound, Creep, Creep Modelling, Creep Damage Characterization, Failure Analysis, Acoustic Emission, Electrical Resistance, Environmental Barrier Coating, EBC, CVI-SiC Creep, SiC Fibers Creep, Stress Dependent Matrix Cracking

Layton, Kyle WilliamAn Evaluation of Monitoring and Preservation Techniques for the Main Cables of the Anthony Wayne Bridge
Master of Science in Civil Engineering, University of Toledo, 2013, Civil Engineering
The main cable of a suspension bridge is a fracture critical element which is difficult to inspect. The research presented in this thesis investigates this universal problem plaguing owners of suspension bridges across the globe. It is well known that the leading issue associated with deterioration and aging of steel bridges is corrosion. In most cases, visual inspection of structural members has long been an adequate method for monitoring steel structures exposed to environmental conditions which lead to corrosion. In the case of suspension bridges, it is possible to visually inspect the deck and towers with minimal difficulty; however, visual inspection of the main cables is both difficult and expensive. It is not possible to visually inspect the entire volume of the cable in a practical, cost-effective way. For this reason the current solution is to perform an invasive inspection in accordance with the NCHRP-534, which attempts to maximize the probability of estimating the condition of the cable while minimizing effort and expenses. These issues have lead researchers to look for nondestructive methods of determining the condition of the cable. The methods discussed in this thesis include acoustic monitoring, embedded sensors, and magnetic inspection through the magnetic main flux method. In addition, the study sought to identify the best available procedures for protecting the cables of suspension bridges from corrosion. Dehumidification, a method of controlling the cable environment to prevent corrosion, was identified as a promising preservation technology and is compared to traditional protection strategies. This study includes laboratory research on corrosion monitoring through acoustic emission and has evaluated both the available monitoring and preservation strategies for suspension bridge main cables. The research was performed for the Ohio Department of Transportation, and the results will have a direct impact on the Anthony Wayne Bridge in Toledo, OH. In addition, the information contained within this document provides useful information for suspension bridge owners across the country.

Committee:

Douglas Nims (Advisor); Brian Randolph (Committee Member); Ali Fatemi (Committee Member)

Subjects:

Civil Engineering

Keywords:

suspension bridge; corrosion; bridge wires; acoustic emission; internal sensors; magnetic cable inspection; dehumidification

Cao, DemingInvestigation of Acoustic Emission and Surface Treatment to Improve Tool Materials and Metal Forming Process
Doctor of Philosophy (Ph.D.), University of Dayton, 2010, Materials Engineering

Silicon nitride and WC-Co cermet tools are used for metal forming processes including extrusion and drawing. These materials are used to make tool dies which are exposed to deformation caused by friction and wear.

Surface treatments such as ion implantation, laser blazing and coating have been found to improve surface properties, to optimize tribological behavior between the metal and die, as well as to extend service life of the tool dies. Early detection and continuous monitoring processes by non destructive testing (NDT) methods are needed in order to ensure the functionality of the wear process and extend the tool service life. Acoustic emission is one of the promising NDT methods for this application.

The surface treatment chosen for this investigation was ion implantation. Three types of wear resistant materials with and without surface treatment were selected for this project; silicon nitride and two tungsten carbides (6% Cobalt and 10% Cobalt).

This investigation was conducted using a pin-on-disk device for wear/friction tests of the selected materials with lubrication and/or without lubrication against both a stainless steel disk and an aluminum disk. The acoustic emissions generated during the experiments were recorded and analyzed.

The results of this investigation showed that the ion implantation improved the tribological properties of the materials and reduced acoustic emission and coefficient of friction. A linear relationship between the average amplitude of the acoustic emission and the coefficient of friction of the tested materials was found. The investigation demonstrated that the acoustic emission method could be used to monitor the wear/friction processes.

Committee:

Norbert Meyendorf (Committee Chair); Daniel Eylon (Committee Member); Norman Hecht (Committee Member); Paul Murray (Committee Member); Gerald Shaughnessy (Committee Member)

Subjects:

Engineering; Materials Science

Keywords:

acoustic emission; silicon nitride; ungsten carbide; ion implantation; tool materials

Han, PeidongA Study on Electrolytic In-Process Dressing (ELID) Grinding of Sapphire with Acoustic Emission Monitoring
Master of Science in Mechanical Engineering, University of Toledo, 2009, Mechanical Engineering

Single crystal sapphire is of significant interest due to its combination of excellent physical, optical, electrical, chemical and mechanical properties. However, fine grinding of sapphire is quite challenging because of its high hardness and low fracture toughness, making it sensitive to cracking. Furthermore, wheel loading is another common problem in conventional grinding of hard and brittle materials.

A new technique, Electrolytic In-process Dressing (ELID) grinding, shows great promise in overcoming the problems of conventional grinding of hard and brittle materials. This technology provides continuous dressing of metal-bonded wheels during the grinding process, while maintaining sharp abrasives from the superabrasive wheels.

In this research, ELID technique was applied in the grinding of sapphire in order to obtain super surface finish and to minimize the problems in conventional grinding of sapphire. The research was focused on the pre-dressing oxide layer thickness, surface finish quality, and acoustic emission monitoring of the ELID grinding process. The effects of processing parameters on the oxide layer thickness, surface finish, and acoustic emission signals were evaluated. Correlations were found among the dressing current intensity, oxide layer thickness, surface finish and acoustic emission signals. A smoother surface was obtained using a higher dressing current at the cost of a higher wheel wear rate. The wheel wear mechanism in ELID grinding of sapphire is dominated by bond fracture because the bond strength is reduced by electrolysis. Results indicate that the acoustic emission technique has the potential to be used for monitoring the ELID grinding process, detecting the condition of the grinding wheel, and investigating the mechanisms of ELID grinding.

Committee:

Ioan Marinescu (Advisor); Mehdi Pourazady (Committee Member); Hongyan Zhang (Committee Member)

Subjects:

Engineering

Keywords:

ELID Grinding; Acoustic Emission; Sapphire

Dhulubulu, AdityaAcoustic Emission (AE) monitoring of the milling process with coated metal carbide inserts using TRIM C270 cutting fluid
Master of Science, University of Toledo, 2015, Mechanical Engineering
The use of Metal working fluids for any cutting mechanism has been found to affect the tool wear in a positive manner, but more importantly it is the way of applying this fluid that has significantly impacted the tool wear. In this study, experiments were conducted on AISI 4140 alloy steel to determine the performance of three different applications of cutting fluid using an end milling process. TiAlN coated metal carbide inserts were used for cutting under three different levels of surface speed, chip load and depth of cut. The response variables collected were Acoustic Emission (AE), Forces, Temperature and Tool wear based on which, cutting fluid applications were categorized for their performances. In addition, more emphasis was given on the AE results to observe its potential to provide necessary real time knowledge and tool wear monitoring capability during cutting process. AE Hit values were recorded as a parameter to study the tool wear results based on different ways of fluid applications. The results in this research point to the fact that different ways of applying a cutting fluid impacts the tool wear, forces, temperature and the acoustic signals in a positive manner. Furthermore, three statistical models to predict the tool wear in near future were proposed based on the response variables from this research.

Committee:

Ioan Marinescu, Dr (Advisor); Efstratios Nikolaidis, Dr (Committee Member); Matthew Franchetti, Dr (Committee Member)

Subjects:

Mechanical Engineering; Technology

Keywords:

Acoustic Emission, Force measurements, Temperature Measurement, Flooding, Misting, Through Tool, TRIM C270

Appleby, Matthew P.High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings
Doctor of Philosophy, University of Akron, 2016, Mechanical Engineering
Novel high-temperature experiments were conducted in ordered to address some of the most critical life-limiting issues facing woven melt-infiltrated, silicon carbide (SiC) fiber-reinforced SiC ceramic matrix composites (CMCs) as well as protective thermal and environmental barrier coatings (T/EBC). Heating of specimens was achieved using laser-based approaches that simulate the high heat-flux thermal gradient environments that these materials will be subjected to in service. Specialized non-destructive evaluation (NDE) and inspection techniques were developed to investigate damage modes and material response. First, in order to examine the capabilities of utilizing the emerging technique of electrical resistance (ER) measurement for use in high temperature mechanical testing in SiC/SiC CMCs, the temperature dependent ER response of several systems was determined. A model was developed to establish the contribution to overall ER from the individual composite constituents and applied thermal gradient. Then, elevated temperature tensile tests were performed to characterize the damage of composite materials to localized stress concentrations. Further experiments were done to assess the differences in damage mechanisms and retained tensile strength properties of uncoated SiC/SiC CMCs and EBC-CMC systems after prolonged exposure to high pressure, high velocity water vapor containing environments. Differences in damage modes were described using ER monitoring and post-test inspection. Localized strain fields were measured using a novel digital image correlation (DIC) technique and stress-dependent matrix crack accumulation was monitored using in-situ modal acoustic emission (AE). Coupled AE and thermography measurements were also used to describe failure of protective ceramic coatings due to the life-limiting case of thermal cyclic loading. Due to the complex nature of T/EBC failure, the decrease in coating life and durability due to thermal stress concentrations and degradation via molten calcium-magnesium-aluminosilicate (CMAS) infiltration was also examined. Finally, the use of ER measurements for damage characterization was extended to the complex case of creep and stress-rupture of damaged and undamaged composites as well as the dramatic increase in stress-rupture life to SiC/SiC CMCs from environmental barrier coatings. Post-test microscopy was performed to further explain differences in material response and damage morphology.

Committee:

Gregory Morscher (Advisor); Manigandan Kannan (Committee Member); Kwek Tze Tan (Committee Member); Craig Menzemer (Committee Member); Alper Buldum (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

ceramic matrix composites; environmental barrier coatings, thermal barrier coatings; non-destructive evaluation; electrical resistance; acoustic emission; digital image correlation

Niroula, KushalAcoustic Monitoring of the Main Suspension Cables of the Anthony Wayne Bridge
Master of Science, University of Toledo, 2014, Civil Engineering
The 82 year old Anthony Wayne Bridge (AWB) in Toledo, Ohio is undergoing an extensive rehabilitation in two phases starting in construction season 2014. The plan is to first replace the approaches and rehabilitate the superstructure. Upon completion of the superstructure rehabilitation, steps to preserve the main suspension cables will be taken. Prior to taking action to preserve the cables, however, it is necessary to evaluate the condition of the cables. Therefore, as part of cable condition evaluation, an acoustic monitoring system was installed on July 2011 and has been continuously monitoring the main cables since then. Acoustic emission (AE) is a non-destructive technique which is practical for monitoring elements of bridges where invasive inspection is either difficult or costly. The AE system can be accessed remotely in real time and it does not cause any interruption to traffic. In the case of a suspension bridge, main cables are of primary concern as their condition cannot be assessed externally unlike other bridge components and they are fracture critical. This paper presents a case study on the application of the acoustic emission technique to the main cables of the AWB. Several laboratory experiments were planned and executed to develop understanding of the potential AE sources. Wire breaks were the primary AE sources under concern. Rain and frictional activities induced by traffic and wind events would create secondary and/or noise sources. The rain, friction and wire break were all simulated in the laboratory and it was verified that, by using a combination of parameters along with signal signatures, a wire break signal can be discriminated against other secondary or noise sources. The AE monitoring system on the AWB uses a series of 7 algorithms that analyze the parameters of each detected AE event. For each feature that meets or exceeds the value of the classification, it is assigned a source type ranging from 0 to 7. Thus for a wire break, the AE signal would meet or exceed all 7 criteria and would receive a `source type’ classification of `7’. The analysis of the data collected on the AWB during January 2013 to June 2013 (excluding May 2013) showed very high acoustic activity near sensors 1, 2, 14 and 15. After further examination it was found that those activities were of frictional nature caused by weather events and traffic induced movements. Many AE events were classified as high as `source type 6’ that occurred during extreme weather events and there was not any `source type 7’ event. This suggests that no wire breaks have been recorded so far. No wire breaks were discovered during the 2012 invasive inspection too, which supports the results from AE monitoring. Meanwhile, the system was unable to capture the signal produced by cutting of wire samples during the invasive inspection and this challenges the reliability of the monitoring system. An `Auto Sensor Test’ performed in March 2014 indicates that there has been degradation in the system’s performance. Many of the sensors do not seem to have proper coupling, thereby causing difficulty in effective signal-source interpretation. Very few AE events were observed in a review of data from the bridge closure period that started on March 17, 2014.

Committee:

Douglas Nims (Advisor); Douglas Nims (Committee Chair); Brian Randolph (Committee Member); Ahalapitiya Jayatissa (Committee Member)

Subjects:

Civil Engineering; Electrical Engineering

Keywords:

Acoustic Monitoring, Main Suspension Cables, Structural Health Monitoring, Non-Destructive Evaluation, Anthony Wayne Bridge, Acoustic Emission

SHINDE, VISHALDEVELOPMENT OF A DATA ACQUISITION SYSTEM AND PIEZOELECTRIC SENSORS FOR AN EXPERIMENTAL STRUCTURAL NEURAL SYSTEM
MS, University of Cincinnati, 2006, Engineering : Mechanical Engineering
This thesis develops a data acquisition system and long piezoelectric sensors for a technique of structural health monitoring based on a structural neural system and continuous sensors. The structural neural system uses distributed sensing and parallel signal processing in real time to monitor large structures like an aircraft for damage. The structural neural system consists of piezoceramic nerves and electronic logic circuits and was tested on an aluminum plate that was fatigue loaded using a mechanical testing machine. The testing indicated that the SNS analog processor using conventional monolithic piezoceramic sensors was able to detect the acoustic emissions using continuous fiber sensors. The acoustic emission level in aluminum was small but detectable. A higher sensitivity of the neural system was needed. Therefore, further sensor development was undertaken including fabricating piezoelectric active fiber continuous sensors. The testing in this thesis indicates that the continuous sensor can becloser to the damage site, and is more sensitive than conventional discrete sensors. In thisthesis a data acquisition system was developed using LabVIEW and single fiber continuous sensors were developed for the structural neural system. The testing indicates that the structural neural system will be able to continuously monitor a structure and provide a long-term history of the health of the structure.

Committee:

Dr. Mark Schulz (Advisor)

Subjects:

Engineering, Mechanical

Keywords:

Structural Health Monitoring; Acoustic Emission; AE; NDT; Piezo; Piezoelectric sensors; AFC; Composite Sensors; Smart Materials; Data Acquisition; DAQ; LabVIEW.

Gordon, Neal AMaterial Health Monitoring of SIC/SIC Laminated Ceramic Matrix Composites With Acoustic Emission And Electrical Resistance
Master of Science in Engineering, University of Akron, 2014, Mechanical Engineering
Ceramic matrix composites (CMC) composed of Hi-Nicalon Type S™ fibers, a boron-nitride (BN) interphase, and pre-impregnated (pre-preg) melt-infiltrated silicon / silicon-carbide (SiC) matrix have been studied at room-temperature consisting of unidirectional and cross-ply laminates. Quasi-static, hysteretic and uniaxial tensile tests were done in conjunction with a variety of temporary, laboratory-based material health-monitoring techniques such as electrical resistance (ER) and acoustic emission (AE). The mechanical stress-strain relationship paired with electrical and acoustic measurements were analyzed to expand upon current composite knowledge to develop a more fundamental understanding of the failure of brittle matrix laminates, their constituents, and interactions. In addition, a simple but effective method was developed to allow visual confirmation of post-test crack spacing via microscopy. To enhance fidelity of acquired data, some specimens were heat-treated (i.e. annealing) in order to alter the residual stress state. Differences in location, acoustic frequency, and magnitude of matrix cracking for different lay-ups have been quantified for unidirectional and [0/90] type architectures. Empirical results shows complex hysteretic mechanical and electrical behavior due to fiber debonding and frictional sliding of which no general model exists to capture the essence of this CMC system. The results of this work may be used in material research and development, stress analysis and design verification, manufacturing quality control, and in-situ system and component monitoring.

Committee:

Gregory Morscher, Dr. (Advisor); Wieslaw Binienda, Dr. (Committee Member); Tirumalai Srivatsan, Dr. (Committee Member)

Subjects:

Aerospace Materials; Mechanical Engineering

Keywords:

Ceramic Matrix Composite,CMC;Aerospace;Non-Destructive Evaluation,NDE;Structural Health Monitoring,SHM;Composites;Acoustic Emission;Electrical Resistance