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Full-Text Articles in Engineering
Mechanical Characterization Of Bamboo And Glass Fiber Biocomposite Laminates, Matthew Siniawski
Mechanical Characterization Of Bamboo And Glass Fiber Biocomposite Laminates, Matthew Siniawski
Mechanical Engineering Faculty Works
Single-ply biocomposite laminates were fabricated with two different woven fabrics and a bio-based resin using a wet layup technique at room temperature. A highly elastic, stockinette weave bamboo fiber fabric and a thicker, inelastic plain weave bamboo fabric were both investigated. The elastic fabric was pre-strained at 25% intervals, ranging from 0-100% of its original length. Samples made with E-Glass and S-Glass, two common glass fiber reinforcements, were also fabricated using the bioresin as benchmarks. The ultimate strength and modulus of elasticity characteristics of the composites were determined using the ASTM D3039/ D3039M-08 standard test method for determining the tensile …
Creating Learning Through Service Opportunities For Engineering Students: Lessons Learned From A Primarily Undergraduate Liberal Arts University, Matthew Siniawski, Jose A. Saez, Jeremy Pal, Sandra Luca
Creating Learning Through Service Opportunities For Engineering Students: Lessons Learned From A Primarily Undergraduate Liberal Arts University, Matthew Siniawski, Jose A. Saez, Jeremy Pal, Sandra Luca
Mechanical Engineering Faculty Works
The challenge of creating impactful and long-lasting service opportunities for engineering students lies in how to best implement programs in the unique setting of each academic institution. This paper presents a critical reflection of two different models of learning through service opportunities for engineering students that have evolved over the past six years at Loyola Marymount University. In particular, we highlight the history and lessons learned from four different case studies involving both extra-curricular international service projects and course-based service-learning opportunities for engineering students. Overall lessons learned that emerged from our experience include: 1) Students should receive course credit for …
Effect Of Stretch Orientation And Rolling Orientation On The Mechanical Properties Of 2195 Al-Cu-Li Alloy, Omar S. Es-Said, C. J. Parrish, C. A. Bradberry, J. Y. Hassoun, R. A. Parish, A. Nash, N. C. Smythe, K. N. Tran, T. Ruperto, E. W. Lee, D. Mitchell, C. Vinquist
Effect Of Stretch Orientation And Rolling Orientation On The Mechanical Properties Of 2195 Al-Cu-Li Alloy, Omar S. Es-Said, C. J. Parrish, C. A. Bradberry, J. Y. Hassoun, R. A. Parish, A. Nash, N. C. Smythe, K. N. Tran, T. Ruperto, E. W. Lee, D. Mitchell, C. Vinquist
Mechanical Engineering Faculty Works
Sheets of 2195 aluminum-lithium alloy were solution-treated at 507 A degrees C for 30 min. One set was stretched to 3-5% in the 0A degrees, 45A degrees, and 90A degrees angle with respect to the original rolling direction. Two other sets were rolled 6% reduction in thickness and 24% reduction in thickness in the 0A degrees, 45A degrees, and 90A degrees angle with respect to the original rolling direction. All specimens were aged at 143 A degrees C for 36 h. A second group of samples was rolled at 24 and 50% reduction in thickness after a solution treatment of …
On The Distortion And Warpage Of 7249 Aluminum Alloy After Quenching And Machining, N. Keleshian, R. Kyser, J. Rodriquez, C. Cueva, V. Vega, E. W. Lee, J. Ogren, Omar S. Es-Said
On The Distortion And Warpage Of 7249 Aluminum Alloy After Quenching And Machining, N. Keleshian, R. Kyser, J. Rodriquez, C. Cueva, V. Vega, E. W. Lee, J. Ogren, Omar S. Es-Said
Mechanical Engineering Faculty Works
The objective of this study is to determine the effect of solution treatment temperature, quenching media, and various machining sequences on the warpage behavior of aluminum 7249 alloy aged to T6 and T7' tempers. Large extrusions of 7249 aluminum alloy with fins were cut into 108 "T" sections. The samples were solution-treated, aged, and machined. Three solution temperatures (445, 474, and 505 A degrees C), two quenching media (water and 20% polyalkylene glycol), two aging treatments (T6 and T7'), and three machine sequences were used. The flatness of the samples was measured on the surfaces orthogonal to the z-axis. Three …
Innovative Manufacturing Process For Defect Free, Affordable, High Pressure, Thin Walled, Hydraulic Tubing, W. Miranda, G. Takiguchi, T. Shimabukuro, L. Mclennan, C. Agajanian, L. Quintero, D. Mismar, J. Abdulla, C. Andrews, M. Hahn, E. Fodran, E. W. Lee, H. Garmestani, R. D. Conner, D. Brick, J. Ogren, Omar S. Es-Said
Innovative Manufacturing Process For Defect Free, Affordable, High Pressure, Thin Walled, Hydraulic Tubing, W. Miranda, G. Takiguchi, T. Shimabukuro, L. Mclennan, C. Agajanian, L. Quintero, D. Mismar, J. Abdulla, C. Andrews, M. Hahn, E. Fodran, E. W. Lee, H. Garmestani, R. D. Conner, D. Brick, J. Ogren, Omar S. Es-Said
Mechanical Engineering Faculty Works
Various thermo-mechanical processes were performed on a standard and a low oxygen content Ti-6Al-4V alloy. Testing was performed to determine whether it was possible to achieve a combination of tensile properties comparable to those of Ti-3Al-2.5V by means of cold working and annealing Ti-6Al-4V from a thickness of 0.671 cm (0.264 in.) to that between 0.081 and 0.094 cm (0.032-0.037 in.), which had never been carried out before. The resulting mechanical properties of this study were compared to the mechanical properties of Ti-3Al-2.5V to determine whether Ti-6Al-4V could be used as a suitable replacement for hydraulic tubing applications. The optimum …
The Effects Of Retrogression And Reaging On Aluminum Alloy 2195, N. Ward, A. Tran, A. Abad, E. W. Lee, M. Hahn, E. Fordan, Omar S. Es-Said
The Effects Of Retrogression And Reaging On Aluminum Alloy 2195, N. Ward, A. Tran, A. Abad, E. W. Lee, M. Hahn, E. Fordan, Omar S. Es-Said
Mechanical Engineering Faculty Works
A retrogression and reaging (RRA) treatment was performed on 2195 Al-Li Alloy. The exposure times were from 5 to 60 min, and the temperatures were from 200 to 250 A degrees C. Samples that were exposed to a salt spray test had overall similar mechanical properties as compared to those that were not exposed. The percent elongation, however, was significantly deteriorated due to the salt spray exposure. The mechanical properties of the 2195 samples were compared to those of 2099 samples exposed to similar treatments in an earlier study.
The Effects Of Retrogression And Reaging On Aluminum Alloy 2099 (C458), N. Ward, A. Tran, A. Abad, E. W. Lee, M. Hahn, E. Fordan, Omar S. Es-Said
The Effects Of Retrogression And Reaging On Aluminum Alloy 2099 (C458), N. Ward, A. Tran, A. Abad, E. W. Lee, M. Hahn, E. Fordan, Omar S. Es-Said
Mechanical Engineering Faculty Works
The objective of this study was to investigate the feasibility of performing retrogression and reaging (RRA) heat treatments on 2099 aluminum-lithium alloy. The retrogression temperatures were 200-250 A degrees C and retrogression times were 5-60 min. Half of the samples were exposed to a salt fog environment. Interestingly, the samples exposed to salt spray had consistently higher mechanical tensile properties than those which were not exposed.
The Effect Of Layer Orientation On The Mechanical Properties And Microstructure Of A Polymer, V. Vega, J. Clements, T. Lam, A. Abad, B. Fritz, N. Ula, Omar S. Es-Said
The Effect Of Layer Orientation On The Mechanical Properties And Microstructure Of A Polymer, V. Vega, J. Clements, T. Lam, A. Abad, B. Fritz, N. Ula, Omar S. Es-Said
Mechanical Engineering Faculty Works
Rapid Prototyping (RP) is a method used everywhere from the entertainment industry to healthcare. Layer orientation is an important aspect of the final product. The objective of this research was to evaluate the effect of layer orientation on the mechanical strength and toughness of a polymer. The polymer used was a combination of two materials, ZP 130 and ZB 58, fused together in the Z Corporation Spectrum Z510 Rapid Prototyping Machine. ZP 130 is a powder composed of vinyl polymer (2-20%), sulfate salt (0-5%), and plaster that contains < 1% crystalline silica (50-95%). ZB 58 is a liquid composed of glycerol (1-10%), preservative (sorbic acid salt) (0-2%), surfactant (< 1%), pigment (< 1%), and water (85-95%). After removal from the machine the samples were sealed with Z bond 101 which is Beta-methoxyethyl cyanoacrylate (60-100%). The layer orientations studied were the crack arrestor, crack divider, and short transverse with various combinations of the three, for a total of seven orientations. The mechanical strength was evaluated using tensile testing and three-point bend testing. The toughness was evaluated by Izod impact testing. Five samples for tensile testing and three-point bend testing as well as 15 samples for the Izod impact test for each of the seven orientations were made. The total number of samples was 175. The crack arrestor orientation was the strongest main orientation for the tensile and three-point bend test. Weibull analysis was done on the Izod impact testing due to high variation in the results for the crack arrestor and short transverse directions. It was found that the layer orientation and surface roughness played a significant role in the penetration of the Z bond 101 coating and in the overall strength of the samples.
Analysis Of Heat Effects On Marine Corps Am2 Mat Mechanical Properties, V. Vega, U. N. Huynh, J. Holmes, J. Dechellis, P. Stoyanov, D. Piatkowski, E. W. Lee, J. Ogren, N. Drusina, Omar S. Es-Said
Analysis Of Heat Effects On Marine Corps Am2 Mat Mechanical Properties, V. Vega, U. N. Huynh, J. Holmes, J. Dechellis, P. Stoyanov, D. Piatkowski, E. W. Lee, J. Ogren, N. Drusina, Omar S. Es-Said
Mechanical Engineering Faculty Works
Navy AM2 mats are used as portable aircraft landing platforms for the Short Take-off/Vertical Landing (STOVL) aircraft operations. This investigation presents the study performed to determine whether the surface discoloration is a precursor to degradation in the mechanical property of the AM2 mat material. The red discoloration on the mat surfaces had a clear correlation with the decrease in yield strength, ultimate strength, and hardness properties.
Tensile Properties And Microstructures Of Laser-Formed Ti-6al-4v, J. Alcisto, A. Enriquez, H. Garcia, S. Hinkson, T. Steelman, E. Silverman, P. Valdovino, H. Gigerenzer, J. Foyos, J. Ogren, J. Dorey, K. Karg, T. Mcdonald, Omar S. Es-Said
Tensile Properties And Microstructures Of Laser-Formed Ti-6al-4v, J. Alcisto, A. Enriquez, H. Garcia, S. Hinkson, T. Steelman, E. Silverman, P. Valdovino, H. Gigerenzer, J. Foyos, J. Ogren, J. Dorey, K. Karg, T. Mcdonald, Omar S. Es-Said
Mechanical Engineering Faculty Works
The room temperature tensile properties of Ti-6Al-4V alloy prepared under two different processing routes were evaluated and compared. One group of samples was prepared by conventional casting-forging-rolling into flat plates. The other group was prepared by using Triton's Laser Free-Form Fabrication (LF3)(TM) processes, i.e., a laser was used to melt pre-alloyed powders of the required metallic composition as they were dropped onto a moveable substrate programmed to move in such a manner as to form a solid alloy plate. Five populations of Ti-6Al-4V were evaluated: a standard wrought form, an as-deposited form, a machined as-deposited form, a heat-treated as-deposited form, …
Nanofluid Optical Property Characterization: Towards Efficient Direct Absorption Solar Collectors, R. A. Taylor, P. E. Phelan, Todd Otanicar, R. Adrian, R. Prasher
Nanofluid Optical Property Characterization: Towards Efficient Direct Absorption Solar Collectors, R. A. Taylor, P. E. Phelan, Todd Otanicar, R. Adrian, R. Prasher
Mechanical Engineering Faculty Works
Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 mu m). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness >= 10 cm) with extremely low nanoparticle volume fractions - less than 1 x 10(-5), or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase.
Applicability Of Nanofluids In High Flux Solar Collectors, R. A. Taylor, P. E. Phelan, Todd Otanicar, C. A. Walker, M. Nguyen, S. Trimble, R. Prasher
Applicability Of Nanofluids In High Flux Solar Collectors, R. A. Taylor, P. E. Phelan, Todd Otanicar, C. A. Walker, M. Nguyen, S. Trimble, R. Prasher
Mechanical Engineering Faculty Works
Concentrated solar energy has become the input for an increasing number of experimental and commercial thermal systems over the past 10-15 years [M. Thirugnanasambandam et al., Renewable Sustainable Energy Rev. 14 (2010)]. Recent papers have indicated that the addition of nanoparticles to conventional working fluids (i.e., nanofluids) can improve heat transfer and solar collection [H. Tyagi et al., J. Sol. Energy Eng. 131, 4 (2009); P. E. Phelan et al., Annu. Rev. Heat Transfer 14 (2005)]. This work indicates that power tower solar collectors could benefit from the potential efficiency improvements that arise from using a nanofluid working fluid. A …
Parametric Analysis Of A Coupled Photovoltaic/Thermal Concentrating Solar Collector For Electricity Generation, Todd Otanicar, I. Chowdhury, P. E. Phelan, R. Prasher
Parametric Analysis Of A Coupled Photovoltaic/Thermal Concentrating Solar Collector For Electricity Generation, Todd Otanicar, I. Chowdhury, P. E. Phelan, R. Prasher
Mechanical Engineering Faculty Works
The analysis of the combined efficiencies in a coupled photovoltaic (PV)/thermal concentrating solar collector are presented based on a coupled electrical/thermal model. The calculations take into account the drop in efficiency that accompanies the operation of PV cells at elevated temperatures along with a detailed analysis of the thermal system including losses. An iterative numerical scheme is described that involves a coupled electrothermal simulation of the solar energy conversion process. In the proposed configuration losses in the PV cell due to reduced efficiencies at elevated temperatures and the incident solar energy below the PV bandgap are both harnessed as heat. …
Nanofluid-Based Direct Absorption Solar Collector, Todd Otanicar, P. E. Phelan, R. S. Prasher, G. Rosengarten, R. A. Taylor
Nanofluid-Based Direct Absorption Solar Collector, Todd Otanicar, P. E. Phelan, R. S. Prasher, G. Rosengarten, R. A. Taylor
Mechanical Engineering Faculty Works
Solar energy is one of the best sources of renewable energy with minimal environmental impact. Direct absorption solar collectors have been proposed for a variety of applications such as water heating; however the efficiency of these collectors is limited by the absorption properties of the working fluid, which is very poor for typical fluids used in solar collectors. It has been shown that mixing nanoparticles in a liquid (nanofluid) has a dramatic effect on the liquid thermophysical properties such as thermal conductivity. Nanoparticles also offer the potential of improving the radiative properties of liquids, leading to an increase in the …
Evaluation Of The Effects Of Powder Coating Cure Temperatures On The Mechanical Properties Of Aluminum Alloy Substrates, C. Maldonado, D. Diaz, J. Ranallo, R. Painter, W. Dahir, D. Hassouna, B. Gayer, E. Toss, I. Martinez, P. Stoyanov, J. Ogren, E. W. Lee, D. Piatkowski, Omar S. Es-Said
Evaluation Of The Effects Of Powder Coating Cure Temperatures On The Mechanical Properties Of Aluminum Alloy Substrates, C. Maldonado, D. Diaz, J. Ranallo, R. Painter, W. Dahir, D. Hassouna, B. Gayer, E. Toss, I. Martinez, P. Stoyanov, J. Ogren, E. W. Lee, D. Piatkowski, Omar S. Es-Said
Mechanical Engineering Faculty Works
The effects of curing temperature, based on new, low-temperature powder coating methods and traditional high-temperature powder coating methods, were studied. Heat-sensitive aluminum alloys (2024-T3, 6061-T6, and 7075-T6) were subjected to two different heat-treatment cycles, which were based on temperatures of 121 and 204 degrees C. Findings indicate that although both cure temperatures achieved powder coatings adhesion and thickness appropriate for industrial uses, the high-temperature cure treatment negatively affected the mechanical properties.
Vapor Generation In A Nanoparticle Liquid Suspension Using A Focused, Continuous Laser, R. A. Taylor, P. E. Phelan, Todd Otanicar, R. J. Adrian, P. S. Prasher
Vapor Generation In A Nanoparticle Liquid Suspension Using A Focused, Continuous Laser, R. A. Taylor, P. E. Phelan, Todd Otanicar, R. J. Adrian, P. S. Prasher
Mechanical Engineering Faculty Works
This letter discusses experimentation with optically induced phase change in nanoparticle liquid suspensions-commonly termed nanofluids. Four different types of nanofluids at five concentrations were exposed to a similar to 120 mW, 532 nm laser beam to determine the minimum laser flux needed to create vapor. Laser irradiance was varied between 0-770 W cm(-2). While the experiments were simple, they involved many complex, interrelated physical phenomena, including: subcooled boiling, thermal driven particle/bubble motion, nanoparticle radiative absorption/scattering, and nanoparticle clumping. Such phenomena could enable novel solar collectors in which the working fluid directly absorbs energy and undergoes phase change in a single …
Computational And Experimental Investigation Of The Flow Structure And Vortex Dynamics In The Wake Of A Formula 1 Tire, John Axerio, Gianluca Iaccarino, Emin Issakhanian, Chris Elkins, John Eaton
Computational And Experimental Investigation Of The Flow Structure And Vortex Dynamics In The Wake Of A Formula 1 Tire, John Axerio, Gianluca Iaccarino, Emin Issakhanian, Chris Elkins, John Eaton
Mechanical Engineering Faculty Works
The flowfield around a 60% scale stationary Formula 1 tire in contact with the ground in a closed wind tunnel was examined experimentally in order to assess the accuracy of different turbulence modeling techniques. The results of steady RANS and Large Eddy Simulation (LES) were compared with PIV data, which was obtained within the same project. The far wake structure behind the wheel was dominated by two strong counter-rotating vortices. The locations of the vortex cores, extracted from the LES and PIV data as well as computed using different RANS models, showed that the LES predictions are closest to the …
Abrasiveness Of Boron Carbide Coatings, Matthew Siniawski
Abrasiveness Of Boron Carbide Coatings, Matthew Siniawski
Mechanical Engineering Faculty Works
No abstract provided.
Microstructure Analysis Of Aluminum Alloy And Copper Alloy Circular Shells After Multiaxial Plastic Buckling, N. Drusina, R. Mahapatra, A. Abdul-Latif, R. Baleh, C. Wilhelm, P. Stoyanov, Omar S. Es-Said
Microstructure Analysis Of Aluminum Alloy And Copper Alloy Circular Shells After Multiaxial Plastic Buckling, N. Drusina, R. Mahapatra, A. Abdul-Latif, R. Baleh, C. Wilhelm, P. Stoyanov, Omar S. Es-Said
Mechanical Engineering Faculty Works
Aluminum and copper cylindrical shells were plastically buckled under quasi-static and dynamic loading conditions with an Absorption Compression-Torsion Plasticity (ACTP: Patent No. WO 2005090822) combined mechanical testing device. Optical microscopy and transmission electron microscopy (TEM) analysis were used to study the microscopic evolutions in the mechanically buckled aluminum and copper alloy samples. Optical microscopy showed evidence of the presence of second-phase particles in both the aluminum and copper alloys samples. Under dynamic loading aluminum samples showed more energy absorption as compared to copper samples. Material flow lines were more pronounced in the copper samples when observed by optical microscopy. The …
Evaluation Of Advanced Adhesives For Aerospace Structures, P. Stoyanov, N. Rodriguez, T. Dickinson, D. H. Nguyen, E. Park, J. Foyos, V. Hernandez, J. Ogren, Michael Berg, Omar S. Es-Said
Evaluation Of Advanced Adhesives For Aerospace Structures, P. Stoyanov, N. Rodriguez, T. Dickinson, D. H. Nguyen, E. Park, J. Foyos, V. Hernandez, J. Ogren, Michael Berg, Omar S. Es-Said
Mechanical Engineering Faculty Works
Polymer adhesives are finding increased use in panel joining applications in aircraft and aerospace structures where the applied stresses permit their use and where a uniform stress distribution is needed. One such adhesive, Hysol EA-9394 (TM), was compared to three other formulations in this study. The new formulations were Hysol EA-9396, Hysol EA-9396 filled with nickel nanofibers and mixed by machine (Jamesbury Blender), and Hysol EA-9396 filled with nickel nanofibers and hand mixed in the laboratory. The comparison consisted of measuring shear lap strengths of aluminum test pieces bonded together with the candidate adhesives. The mechanical tests were supplemented by …
Effects Of Heat Treatments On Steels For Bearing Applications, K. Clemons, C. Lorraine, G. Salgado, A. Taylor, J. Ogren, P. Umin, Omar S. Es-Said
Effects Of Heat Treatments On Steels For Bearing Applications, K. Clemons, C. Lorraine, G. Salgado, A. Taylor, J. Ogren, P. Umin, Omar S. Es-Said
Mechanical Engineering Faculty Works
AISI 52 100, 440C, REX20, and Crucible CRU80 steel samples were exposed to 16 different heat treatments to vary the levels of retained austenite. Rockwell C hardness measurements, optical microscopy, and compression testing were used to compare the properties of the different steels.
Effect Of Cold Work On The Tensile Properties Of 6061, 2024, And 7075 Al Alloys, D. Ortiz, M. Abdelshehid, R. Dalton, J. Soltero, R. Clark, M. Hahn, E. Lee, W. Lightell, B. Pregger, J. Ogren, P. Stoyanov, Omar S. Es-Said
Effect Of Cold Work On The Tensile Properties Of 6061, 2024, And 7075 Al Alloys, D. Ortiz, M. Abdelshehid, R. Dalton, J. Soltero, R. Clark, M. Hahn, E. Lee, W. Lightell, B. Pregger, J. Ogren, P. Stoyanov, Omar S. Es-Said
Mechanical Engineering Faculty Works
Aluminum alloys 6061, 2024, and 7075 were heat treated to various tempers and then subjected to a range of plastic strain (stretching) in order to determine their strain limits. Tensile properties, conductivity, hardness, and grain size measurements were evaluated. The effects of the plastic strain on these properties are discussed and strain limits are suggested.
Warpage Behavior Of 7075 Aluminum Alloy Extrusions, Omar S. Es-Said, T. M. Ruperto, S. L. Vasquez, A. Y. Yue, D. J. Manriquez, J. C. Quilla, S. H. Harris, S. Hannan, J. Foyos, E. W. Lee, B. Pregger, N. Abourialy, J. Ogren
Warpage Behavior Of 7075 Aluminum Alloy Extrusions, Omar S. Es-Said, T. M. Ruperto, S. L. Vasquez, A. Y. Yue, D. J. Manriquez, J. C. Quilla, S. H. Harris, S. Hannan, J. Foyos, E. W. Lee, B. Pregger, N. Abourialy, J. Ogren
Mechanical Engineering Faculty Works
Extruded I sections of 7075-T6 aluminum were machined into four different sections shapes: L, short depth L, T, and short depth 7. The furnace was preheated to 416 degrees C (780 degrees F) and the samples were placed inside. The temperature was raised to 471 degrees C (880 degrees F) and then the samples were quenched in either a 30% polyalkylene Glycol solution or water, both at 15 degrees C (59 degrees F). Points on the distorted samples were recorded before and after the solution treatment; the difference between the measurements indicated the extent of warpage.
The Effect Of Thermal Exposure On The Mechanical Properties Of 2099-T6 Die Forgings, 2099-T83 Extrusions, 7075-T7651 Plate, 7085-T7452 Die Forgings, 7085-T7651 Plate, And 2397-T87 Plate Aluminum Alloys, J. Jabra, M. Romios, J. Lai, E. Lee, M. Setiawan, E. W. Lee, J. Witters, N. Abourialy, J. Ogren, R. Clark, T. Oppenheim, W. E. Frazier, Omar S. Es-Said
The Effect Of Thermal Exposure On The Mechanical Properties Of 2099-T6 Die Forgings, 2099-T83 Extrusions, 7075-T7651 Plate, 7085-T7452 Die Forgings, 7085-T7651 Plate, And 2397-T87 Plate Aluminum Alloys, J. Jabra, M. Romios, J. Lai, E. Lee, M. Setiawan, E. W. Lee, J. Witters, N. Abourialy, J. Ogren, R. Clark, T. Oppenheim, W. E. Frazier, Omar S. Es-Said
Mechanical Engineering Faculty Works
Aluminum alloys 2099-T6 die forgings, 2099-T83 extrusions, 7075-T7651 plate, 7085-T7452 die forgings, 7085-T7651 plate, and 2397-T87 plate were thermally exposed at temperatures of 180 degrees C (350 degrees F), 230 degrees C (450 degrees F), and 290 degrees C (550 degrees F) for 0.1, 0.5, 2, 10, 100, and 1000 h. The purpose of this study was to determine the effect of thermal exposure on the mechanical properties and electrical conductivity of these alloys. The data shows that higher temperatures and longer exposure times generally resulted in decreased strength and hardness and increased percent elongation and electrical conductivity.
Design Of Multistep Aging Treatments Of 2099 (C458) Al-Li Alloy, M. Romios, R. Tiraschi, C. Parrish, H. W. Babel, J. Ogren, Omar S. Es-Said
Design Of Multistep Aging Treatments Of 2099 (C458) Al-Li Alloy, M. Romios, R. Tiraschi, C. Parrish, H. W. Babel, J. Ogren, Omar S. Es-Said
Mechanical Engineering Faculty Works
Multistep artificial aging treatments coupled with various natural aging times for aluminum lithium 2099 alloy (previously called C458) are discussed to obtain mechanical tensile properties in the T6 condition that match those in the T861 condition, having a yield strength in the range of 414-490 MPa (60-71 ksi), an ultimate strength in the range of 496-538 MPa (72-78 ksi), and 10-13% elongation. Yield and ultimate tensile strengths from 90-100% of the strength of the as-received material (in the T861 condition) were obtained. The highest tensile strengths were consistently obtained with two-step, low-to-high temperature artificial aging treatments consisting of a first …
High-Resolution Methods For Measuring The Thermal Expansion Coefficient Of Aerospace Materials, G. Wallace, W. Speer, J. Ogren, Omar S. Es-Said
High-Resolution Methods For Measuring The Thermal Expansion Coefficient Of Aerospace Materials, G. Wallace, W. Speer, J. Ogren, Omar S. Es-Said
Mechanical Engineering Faculty Works
Accurately predicting the coefficient of thermal expansion for many aerospace components is critical to ensure proper functionality on orbit where the temperature gradient across a spacecraft can vary from +300 degrees F to -450 degrees F. Under these conditions, the linear approximations generated by theoretical equations no longer hold true, and experimental methods are needed. Although several methods exist for measuring the coefficient of thermal expansion of materials, laser interferometry yields high-resolution results, and the technique is widely accepted in the scientific community.
The Tribological Role Of Energy Efficiency Within Society, Matthew Siniawski
The Tribological Role Of Energy Efficiency Within Society, Matthew Siniawski
Mechanical Engineering Faculty Works
No abstract provided.
Optimizing The Compression Stress Relief Process For 7050al Forgings, K. Escobar, B. Gonzales, J. Ortiz, P. Nguyen, C. Iskandar, P. Tiscareno, M. Castro, J. Gutierrez, J. Foyos, J. Ogren, Omar S. Es-Said, D. M. Bowden, E. W. Lee
Optimizing The Compression Stress Relief Process For 7050al Forgings, K. Escobar, B. Gonzales, J. Ortiz, P. Nguyen, C. Iskandar, P. Tiscareno, M. Castro, J. Gutierrez, J. Foyos, J. Ogren, Omar S. Es-Said, D. M. Bowden, E. W. Lee
Mechanical Engineering Faculty Works
Structural components machined from aluminum forgings can exhibit distortion and poor dimensional quality due to residual stresses formed primarily during heat treatment. To alleviate these problems, mechanically stress-relieved tempers are used in which a small amount of plastic strain is introduced after solution heat treatment and prior to aging. For hand-forged billets and die forgings, this strain is introduced by compression. Process specifications for compression stress relief typically allow a range of strains, and this process variability can in turn lead to inconsistent forging performance in machining. In addition, since cold work is known to accelerate the aging response and …
Surface Modification Of Titanium Foil Substrates In Experimental Solar Cells, Richard Nishimuro, Omar S. Es-Said
Surface Modification Of Titanium Foil Substrates In Experimental Solar Cells, Richard Nishimuro, Omar S. Es-Said
Mechanical Engineering Faculty Works
A case study involving surface smoothing of titanium foil was obtained from a solar cell research company. It was believed that the rougher surface of metals was responsible for low solar cell efficiency when using titanium foil rather than glass as a substrate. A method was needed to reduce the surface asperity height of the titanium foil from the existing 1 μm to less than 0.1 μm. Several methods were investigated. The recommended method was the use of an excimer laser, a laser powered by excited noble gas-halide molecules as a lasing medium.
On The Excessive Porosity In The Welds Of Ams 4975 Titanium Air Compressor Rotor Duct, Stefanie Roberts, Rachel Hoang, Laura Pate, Joseph Foyos, Richard Nishimuro, Omar S. Es-Said
On The Excessive Porosity In The Welds Of Ams 4975 Titanium Air Compressor Rotor Duct, Stefanie Roberts, Rachel Hoang, Laura Pate, Joseph Foyos, Richard Nishimuro, Omar S. Es-Said
Mechanical Engineering Faculty Works
This case study deals with the existence of excessive porosity in the welds of an air compressor rotor duct. The duct does not meet the testing criteria because the diameters of the pores in the weld exceeded allowable specifications. As such, the duct failed inspection for excessive pore diameter and shrinkage due to welding. At this point, the part was beyond repair, and it was scrapped. The possible causes of failure were analyzed, and it was concluded that the source of the problem was the welding technique.