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Articles 1 - 11 of 11
Full-Text Articles in Engineering
Swelling-Etching Characterization Of Copper (I) Oxide - Pdms For The Development Of Micro/Nano - Particles Composite Mems Corrosion Sensor, Abdoul Kader Maiga
Swelling-Etching Characterization Of Copper (I) Oxide - Pdms For The Development Of Micro/Nano - Particles Composite Mems Corrosion Sensor, Abdoul Kader Maiga
Graduate Theses and Dissertations
The primary objective for this thesis is to contribute to the understanding of the oxide removal process for a corrosion sensing device. The goal for designing such a device is for monitoring corrosion on metallic structures. The sensing material (6.35mm x 1mm discs) of the device is composed of copper (I) oxide particles mixed in some polydimethylsiloxane (PDMS). The PDMS, “housing,” is meant for controlling the oxidation rate through the sensing material. A solvent was used to facilitate the etchant diffusion through the PDMS matrix. Toluene and acetic acid were the ideal solvent and etchant, respectively, for carrying out the …
Creep Of Sylramic-Ibn Fiber Tows At Elevated Temperature In Air And In Silicic Acid-Saturated Steam, Kevin B. Sprinkle
Creep Of Sylramic-Ibn Fiber Tows At Elevated Temperature In Air And In Silicic Acid-Saturated Steam, Kevin B. Sprinkle
Theses and Dissertations
Stressed oxidation experiments on Sylramic-iBN fiber tows were performed to evaluate the novel fiber's mechanical performance, creep behavior, and creep mechanisms. This research effort investigated creep response of Sylramic-iBN fiber tows at elevated temperatures in both air and in silicic acid-saturated steam environments. Creep experiments were conducted at creep stresses ranging from 127 to 762 MPa at 400°C and 500°C in order to examine the mechanical behavior of the Sylramic-iBN fiber tows at temperatures below and above the melting point of boria (450°C). Sylramic-iBN fibers are known to have excellent creep resistance, better than most other non-oxide fibers and significantly …
New Class Of Garnet Nanocomposites For Use In Magnetic Photonic Crystals Prepared By Rf Magnetron Co-Sputtering, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh
New Class Of Garnet Nanocomposites For Use In Magnetic Photonic Crystals Prepared By Rf Magnetron Co-Sputtering, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh
Mikhail Vasiliev
A new class of magneto-optic garnet nanocomposite materials is prepared using two Bi-substituted iron garnet materials of composition types (Bi,Dy) 3(Fe,Ga)5O12 and Bi3Fe 5O12. A composition adjustment approach is applied by varying the radio frequency (RF) powers driving each sputtering target during the deposition process. This new class of nanocomposite materials exhibits simultaneously high specific Faraday rotation, MO figure of merit, and effective uniaxial magnetic anisotropy after being crystallized through optimized annealing processes. We demonstrate experimentally that the excellent combination of materials' properties obtained in this garnet nanocomposite is particularly advantageous for developing magneto-photonic crystals as well as optical sensors …
New Class Of Garnet Nanocomposites For Use In Magnetic Photonic Crystals Prepared By Rf Magnetron Co-Sputtering, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh
New Class Of Garnet Nanocomposites For Use In Magnetic Photonic Crystals Prepared By Rf Magnetron Co-Sputtering, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh
Mikhail Vasiliev
A new class of magneto-optic garnet nanocomposite materials is prepared using two Bi-substituted iron garnet materials of composition types (Bi,Dy) 3(Fe,Ga)5O12 and Bi3Fe 5O12. A composition adjustment approach is applied by varying the radio frequency (RF) powers driving each sputtering target during the deposition process. This new class of nanocomposite materials exhibits simultaneously high specific Faraday rotation, MO figure of merit, and effective uniaxial magnetic anisotropy after being crystallized through optimized annealing processes. We demonstrate experimentally that the excellent combination of materials' properties obtained in this garnet nanocomposite is particularly advantageous for developing magneto-photonic crystals as well as optical sensors …
Waveform-Based Selection Of Acoustic Emission Events Generated By Damage In Composite Materials, Emmanuel Maillet, Gregory Morscher
Waveform-Based Selection Of Acoustic Emission Events Generated By Damage In Composite Materials, Emmanuel Maillet, Gregory Morscher
Dr. Gregory N. Morscher
Acoustic emission (AE) has been shown to be a promising health monitoring technique for composite materials as it allows real-time location and identification of damage. When attempting to relate the recorded acoustic emission to a material׳s mechanical behavior, the relevance of results relies on an accurate selection of AE originating from material damage. Indeed, during mechanical tests most of the recorded AE is generated outside of the volume of interest and without proper filtering these AE signals can significantly affect the analysis. To date, there exists no common procedure for the selection of AE signals and therefore results can hardly …
Short Crack Growth Model In A Particulate Composite Using Nonlinear Elastic Fracture Mechanics, Ying Zhang, Tsuchin Chu, Ajay Mahajan
Short Crack Growth Model In A Particulate Composite Using Nonlinear Elastic Fracture Mechanics, Ying Zhang, Tsuchin Chu, Ajay Mahajan
Dr. Ajay Mahajan
The fracture mechanics model for a long crack does not work very well with short-crack propagation when the initial crack length is less than 5.1 mm (0.2 inch). In order to investigate the short crack effect, a series of tests of particulate composite specimens with long and short cracks were performed and the results recorded on a video tape. This test data was analyzed to determine the fracture parameters. Two initial crack lengths, 2.5 mm (0.1 inches) and 7.6 mm (0.3 inches) were used in the crack propagation tests. Based on the principle of linear elastic fracture mechanics (LEFM), the …
Determination Of Optimal Experimental Parameters For Transient Thermography Imaging Using Finite-Element Models, Tsuchin Chu, Ajay Mahajan, A. Digrgorio, S. Russell
Determination Of Optimal Experimental Parameters For Transient Thermography Imaging Using Finite-Element Models, Tsuchin Chu, Ajay Mahajan, A. Digrgorio, S. Russell
Dr. Ajay Mahajan
A study was conducted to determine the optimal inspection parameters such as range and time for finding defects in carbon/epoxy composite panels using IR thermography imaging. The present paper presents an innovative method for automatically selecting these parameters for evaluating composites based on a series of finite-element models. Such finite-element models of composite panels with flaws at different depth locations were constructed a priori and analysed to estimate the optimal operating parameters. The optimal inspection range and time were identified in the contour plots obtained from the appropriate finite-element analysis results. A graphite–epoxy composite panel with phantom defects at various …
Effect Of Prior Exposure At Elevated Temperatures On Tensile Properties And Stress-Strain Behavior Of Three Oxide/Oxide Ceramic Matrix Composites, Christopher J. Hull
Effect Of Prior Exposure At Elevated Temperatures On Tensile Properties And Stress-Strain Behavior Of Three Oxide/Oxide Ceramic Matrix Composites, Christopher J. Hull
Theses and Dissertations
Thermal stability of three oxide-oxide ceramic matrix composites was studied. The materials studied were NextelTM610/aluminosilicate (N610/AS), NextelTM720/aluminosilicate (N720/AS), and NextelTM720/Alumina (N720/A), commercially available oxide-oxide ceramic composites (COI Ceramics, San Diego, CA). The N610/AS composite consists of a porous aluminosilicate matrix reinforced with laminated woven alumina N610 fibers. The N720/AS and N720/A composites consist of a porous oxide matrix reinforced with laminated, woven mullite/alumina (NextelTM720) fibers. The matrix materials are aluminosilicate in N720/AS and alumina in N720/A. All three composites have no interface between the fibers and matrix, and rely on the porous …
Fatigue Behavior Of Im7/Bmi 5250-4 Composite At Room And Elevated Temperatures, James T. Tipton
Fatigue Behavior Of Im7/Bmi 5250-4 Composite At Room And Elevated Temperatures, James T. Tipton
Theses and Dissertations
The tension-tension fatigue and tension-compression fatigue behaviors of the IM7/BMI 5250-4 composite were investigated. The tension-tension fatigue of the composite with 0/90 and ±45 fiber orientations was studied at 23, 170, and 190°C. The tension-compression fatigue of the composite with 0/90 fiber orientation was examined at 23°C. The tensile and compressive properties of the composite were also evaluated at room and elevated temperatures for both 0/90 and ±45 fiber orientations. Elevated temperature had little effect on the tensile properties of the 0/90 fiber orientation, but strongly influenced the ±45 tensile properties as well as the compressive properties of both fiber …
Tension-Compression Fatigue Of An Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature In Air And Steam Environments, Richard L. Lanser
Tension-Compression Fatigue Of An Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature In Air And Steam Environments, Richard L. Lanser
Theses and Dissertations
Tension-compression fatigue behavior of an oxide-oxide ceramic matrix composite was investigated at 1200°C in air and steam. The composite is comprised of an alumina matrix reinforced with Nextel 720 fibers woven in an eight harness satin weave. The composite relies on a porous matrix for damage tolerance. Compression and tension tests to failure were conducted to characterize basic mechanical properties. Tension-compression fatigue tests were performed at 1 Hz frequency with a ratio of minimum to maximum stress of -1. Maximum stresses ranged from 60-120 MPa. Fatigue run-out (defined as 105 cycles) was achieved in air at 80 MPa and in …
Optical Fiber Sensors For Smart Composite Materials And Structures, Manjusha Ramakrishnan, Yuliya Semenova, Gerald Farrell, Ginu Rajan
Optical Fiber Sensors For Smart Composite Materials And Structures, Manjusha Ramakrishnan, Yuliya Semenova, Gerald Farrell, Ginu Rajan
Books/Book chapters
Composite material structures are widely used in the aerospace, marine, aviation, transport, sport/leisure and civil engineering industries. Such composite material structures are frequently subjected to external perturbations and varying environmental conditions, which may cause the structures to suffer from fatique damage and/or failure, and thus require real-time structural health monitoring (SHM). Of necessity, the diagnosis process and condition monitoring of composite structures are usually carried out during their working life. The goal of such diagnosis is to detect, identify, locate, and assess the defects that my affect the safety or performance of a structure.