Mechanical Engineering Commons^™

Where Do We Stand On The Relationship Between Tau Biomarkers And Mild Cognitive Impairment?, Bryn Martin, Philip Allen

Philip A Allen

We present an editorial on a recent publication by Amlien et al. [2013] in which diffusion tensor imaging (DTI) was used to quantify longitudinal decreases in fractional anisotropy (FA) and increased radial diffusivity (D_R) in patients with mild cognitive impairment (MCI). These longitudinal alterations were found to be greater in MCI patients with high cerebrospinal fluid (CSF) tau levels at baseline and greater than healthy controls. Amlien et al. concluded that tau levels were an important early biomarker for predicting rate of disease progression and outcome. The results of this study are an interesting finding for possible predictive …

Task-Specific And General Cognitive Effects In Chiari Malformation Type I, Philip Allen, James Houston, Joshua Pollock, Christopher Buzzelli, Xuan Li, A. Harrington, Bryn Martin, Francis Loth, Mei-Ching Lien, Jahangir Maleki, Mark Luciano

Philip A Allen

Our objective was to use episodic memory and executive function tests to determine whether or not Chiari Malformation Type I (CM) patients experience cognitive dysfunction.

An Evaluation Of A Stem Program For Middle School Students On Learning Disability Related Ieps, Paul C. Lam, Dennis Doverspike, Julie Zhao, Jiang Zhe, Craig C. Menzemer

Dennis Doverspike

A year long Science, Technology, Engineering and Math (STEM) program was developed for middle schools students on Individualized Education Programs (IEPs) involving learning disabilities. The workshops were designed to encourage students both on IEPs and not on IEPs to explore STEM as a future career choice by building their knowledge and confidence. The participants in the workshops included 11 students on IEPs and 15 students not on IEPs. Parents also provided feedback regarding their attitudes toward the program. The results indicated that there were increases in student participant knowledge and career interest for both the students not on IEPs and …

High School Bridge Program: A Multidisciplinary Stem Research Program, Jiang Zhe, Dennis Doverspike, Julie Zhao, Paul Lam, Craig Menzemer

Dennis Doverspike

A Science, Technology, Engineering and Math (STEM) summer Bridge Program was developed for high school students. The program was designed to encourage students to consider choosing an engineering major in college and to explore STEM as a future career. This was accomplished through a 10-week program involving multidisciplinary research activities. The participants in the program included 33 high school students. Among former participants in position to make a choice in terms of attending college, 100% had chosen to continue on in college, and 86% had chosen to major in a STEM area. The results indicated that that the program had …

A Parametric Analysis Of A Reservoir-Extended Porous Slider Bearing With Self-Circulation And Cavitation Effects, Joshus Johnson, Minel Braun, Kevin Kreider, Gerald Young

Gerald W Young

This work considers a porous slider bearing fed by an external contiguous reservoir. The bearing system consists of a lubricating film, a porous medium, and the external reservoir, which runs along the entire length of the porous medium. The Darcy model is used for modeling the flow inside the porous medium. The translational velocity of the reservoir wall and porous medium, together with the convergent-divergent slider lubricating film profile, acts to pump the fluid out of and into the lubricating film and the reservoir, respectively. Cavitation effects are modeled realistically using the switch function and modified equations of the Elrod …

Entrochemical Thermal Battery Design For Atmospheric Heat Collectors

Sanza Kazadi

Low Cost Solar Chimney Performance-Improving Enhancement, Sanza Kazadi, Meishan Liang, Aaron Togelang, Daniel Chan

Sanza Kazadi

A Parametric Analysis Of A Reservoir-Extended Porous Slider Bearing With Self-Circulation And Cavitation Effects, Joshus Johnson, Minel Braun, Kevin Kreider, Gerald Young

Kevin L. Kreider

This work considers a porous slider bearing fed by an external contiguous reservoir. The bearing system consists of a lubricating film, a porous medium, and the external reservoir, which runs along the entire length of the porous medium. The Darcy model is used for modeling the flow inside the porous medium. The translational velocity of the reservoir wall and porous medium, together with the convergent-divergent slider lubricating film profile, acts to pump the fluid out of and into the lubricating film and the reservoir, respectively. Cavitation effects are modeled realistically using the switch function and modified equations of the Elrod …

Heat Transfer For Turbulent Annular Flow Of High Prandtl Number Fluids, Benjamin Chung, Lindon Thomas, Yi Pang

Yi Pang

Heat transfer for high Prandtl number fluids flowing turbulently in a concentric circular tube annulus with prescribed wall heat flux is investigated analytically. This surface rejuvenation-based analysis is restricted to thermally and hydrodynamically fully developed flow with constant properties and negligible viscous dissipation. This formulation leads to predictions for the Nusselt Number that are in basic agreement with predictions obtained on the basis of earlier eddy diffusivity models for Prandtl number range from 30 to 1000 and Reynolds number range from 10,000 to 1,000,000.

An Analysis Of Heat Transfer In A Turbulent Heat Generating Flow With High Prandtl Numbers, Benjamin Chung, Yi Pang

Yi Pang

Turbulent heat transfer in a circular tube associated with heat generating fluid of high Prandtl number and wall heat flux is investigated analytically. In the present study, a more comprehensive surface renewal type model, the surface rejuvenation model is employed, which accounts for the fact that turbulent eddies do not generally reach the wall itself. Results of the bulk-to-wall temperature difference on the basis of this model are presented graphically in terms of Reynolds number, Prandtl number and the ratio of wall heat flux to internal heat generation for both cases of heating and cooling. Some limiting solutions are compared …

A Surface Rejuvenation Model For Turbulent Heat Transfer In Annular Flow With High Prandtl Number, Benjamin Chung, Lindon Thomas, Yi Pang

Yi Pang

Heat transfer for high Prandtl number fluids flowing turbulently in a concentric circular tube annulus with prescribed wall heat flux is investigated analytically. This surface rejuvenation based analysis is restricted to thermally and hydrodynamically fully developed flow with constant properties and negligible viscous dissipation. This formulation leads to predictions for the Nusselt Number that are in basic agreement with predictions obtained on the basis of earlier eddy diffusivity models for 30 ≤ Pr ≤ 1000 and 104 ≤ Re ≤ 106 .

Experimental And Fem Study Of Thermal Cycling Induced Microcracking In Carbon/Epoxy Triaxial Braided Composites, Chao Zhang, Wieslaw Binienda, Gregory Morscher, Richard Martin, Lee Kohlman

Wieslaw K. Binienda

The microcrack distribution and mass change in T700s/PR520 and T700s/3502 carbon/epoxy braided composites exposed to thermal cycling was evaluated experimentally. Acoustic emission was utilized to record the crack initiation and propagation under cyclic thermal loading between −55 °C and 120 °C. Transverse microcrack morphology was investigated using X-ray computed tomography. The differing performance of two kinds of composites was discovered and analyzed. Based on the observations of microcrack formation, a meso-mechanical finite element model was developed to obtain the resultant mechanical properties. The simulation results exhibited a decrease in strength and stiffness with increasing crack density. Strength and stiffness reduction …

Analytical And Numerical Analysis Of Low Velocity Impact On Metallic Sandwich Panel With Polyurethane Foam Core, Mohsen Mahdian, Hossein Ebrahimi

Hossein Ebrahimi

No abstract provided.

Case Study Evaluation Of Saturation And Corridor Enforcement Patrols, Alexander Maistros, William Schneider, Rick Beverly, Brandon Stakleff

William H. Schneider

Alcohol-related crashes in the United States have consistently accounted for roughly 30% of traffic-related fatalities in the past two decades. The combined efforts of researchers, educators, and law enforcement are needed to reduce the number of alcohol-related crashes and fatalities. Saturation patrols and corridor patrols are two tools that law enforcement agencies may use in their continued efforts. In the current economic climate, local law enforcement agencies and coalitions must operate as efficiently as possible. As a case study, this study focused on the patrol efforts of a task force dedicated to reducing operating a vehicle under the influence (OVI) …

Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan

Anil Patnaik

A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …

The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick

Anil Patnaik

In this article, the influence of bolt holes, specifically their number and layout on strength, deformation, and final fracture behavior of titanium alloy gusset plates under the influence of an external load is presented and discussed. Several plates having differences in both the number and layout of the bolt holes were precision machined and then deformed under quasi-static loading. The specific influence of number of bolt holes and their layout on maximum load-carrying capability and even fracture load was determined. The conjoint influence of bolt number, bolt layout pattern, nature of loading, contribution from local stress concentration, and intrinsic microstructural …

Investigating And Understanding The Fatigue Response And Failure Of Built-Up Welded Beams Of A Titanium Alloy, Anil Patnaik, Narendra Poondla, Udaykar Bathini, Tirumalai Srivatsan, T. Quick

Anil Patnaik

No abstract provided.

Computations And Detailing Of Pressure Vessels Having Unusual Requirements In Design, Anil Patnaik, Ashenafi Hegana, Tirumalai Srivatsan

Anil Patnaik

The provisions of Australian Standard AS 1210-1989 for design and detailing of unfired pressure vessels can be applied to commonly encountered design situations where the shells have small openings. The technique of finite element analysis is a convenient and powerful tool for the purpose of computational stress analysis when the design requirements are such that either the openings are large, or where concentrated loads and/or thermal movements are present. This paper provides a summary of one such practical design of a pressure vessel. While the computational technique using finite element analysis simplifies the stress analysis of pressure vessels considerably, the …

The Bolt Bearing Response And Tensile Deformation Capacity Of Plates Made From A Titanium Alloy, Nicholas Tinl, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan

Anil Patnaik

In this article, the bearing capacity and elongation characteristics of bolt holes in a titanium alloy (i.e., Ti-6Al-4V) deformed in uniaxial tension is presented and discussed. The specific role played by bolt hole confinement on bearing capacity is highlighted. The nature of final fracture is examined and the intrinsic features present on the fracture surface are rationalized in concurrence with macroscopic mechanical response. The behavior of the candidate alloy (Ti-6Al-4V) is compared with conventionally preferred and chosen candidate materials steel and aluminum alloys. An empirical relationship suitable for purpose of structural design is proposed.

A Study Of The Microstructure And Hardness Of Two Titanium Alloys: Commercially Pure And Ti–6al–4v, Narendra Poondla, Tirumalai Srivatsan, Anil Patnaik, M. Petraroli

Anil Patnaik

In this paper, the microstructure and hardness of two titanium alloys was determined and the results are presented and briefly discussed. Samples of the alloy for microstructural examination were prepared from the as-provided stock using standard metallographic procedures and then examined in a low magnification light optical microscope. Both microhardness and macrohardness measurements were made across the polished surfaces of the two titanium materials. Both the microhardness and macrohardness of the Ti–6Al–4V alloy was noticeably higher than the commercially pure counterpart. The intrinsic influence of alloy composition and secondary processing, i.e., annealing, on microstructural development is presented and hardness of …

The Cyclic Fatigue And Final Fracture Behavior Of A Titanium Alloy Taken From Weldments: Influence Of Load Ratio And Orientation, Udaykar Bathini, Tirumalai Srivatsan, Anil Patnaik, C. Menzemer, T. Quick

Anil Patnaik

In this paper, the cyclic stress ampliture controlled high cycle fatigue properties...

Understanding The Mechanical Response Of Built-Up Welded Beams Made From Commercially Pure Titanium And A Titanium Alloy, Anil Patnaik, Narendra Poondla, Craig Menzemer, Tirumalai Srivatsan

Anil Patnaik

During the last two decades, titanium has gradually grown in stature, strength and significance to take on the recognition of being a modern and high performance metal that is noticeably stronger and concurrently lighter than the most widely chosen and used steels in a spectrum of industrial applications. Technological innovations have necessitated reduction of part weight, cost and lead time, including concurrent enhancement of performance of structural parts and components made using titanium and its alloys. This has provided the impetus to develop economically viable structural design methodologies and specifications, while at the same time bringing forth innovative and economically …

On The Use Of Gas Metal Arc Welding For Manufacturing Beams Of Commercially Pure Titanium And A Titanium Alloy, Anil Patnaik, Narendra Poondla, Udaykar Bathini, Tirumalai Srivatsan

Anil Patnaik

A noticeable reduction in the cost of structural components made from titanium, both commercially pure and the alloy counterpart is possible with the concept of built-up welded fabrication. Rolled sheets of the titanium material can be welded together to fabricate a built-up structural component without having to machine the part from a large billet. In this paper, the results of a recent feasibility study on the manufacturing of welded built-up I-beams for large structural applications are presented and discussed. The fillet welds were produced using the pulsed Gas Metal Arc Welding (GMAW-P) process. Commercially pure titanium (Grade 2) and a …

Isolating Corrosion Of Steel Plates Coupled With Titanium, Anil Patnaik, X. Shan, M. Adams, T. Srivatsan, Craig Menzemer, Joe Payer

Anil Patnaik

Over twenty six percent of the bridges in the United States are structurally deficient or functionally obsolete. Corrosion of steel used in structures like bridges and buildings is a problem that has gained increased interest and focused concern. Steel is often the metal that is preferred for use in such applications due to a synergism of ease of availability, acceptable mechanical properties and cost effectiveness. Through the years, titanium has grown in strength, stature and significance to be recognized as an emerging high performance metal that is both stronger and lighter than steel. A distinctive property of titanium and its …

Mechanisms Governing Fatigue, Damage, And Fracture Of Commercially Pure Titanium For Viable Aerospace Applications, Udaykar Bathini, Tirumalai Srivatsan, Anil Patnaik, Craig Menzemer

Anil Patnaik

In this paper, the cyclic stress amplitude controlled high-cycle fatigue properties and final fracture behavior of commercially pure titanium (Grade 2) are presented and discussed. The material characterization was developed and put forth for selection and use in a spectrum of applications spanning the industries of aerospace, defense, chemical, marine, and commercial products. Test specimens were prepared from the as-received plate stock of the material with the stress axis both parallel (longitudinal) and perpendicular (transverse) to the rolling direction of the plate. The test specimens were cyclically deformed at a constant load ratio of 0.1, at different values of maximum …

Extrinsic Influence Of Environment On The Corrosion Behavior Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, K. Manigandan, Tirumalai Srivatsan

Anil Patnaik

A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …

A Study Of The Tensile Deformation And Fracture Behavior Of Commercially Pure Titanium And Titanium Alloy: Influence Of Orientation And Microstructure, Udaykar Bathini, Tirumalai Srivatsan, Anil Patnaik, T. Quick

Anil Patnaik

In this paper, the tensile deformation and fracture behavior of commercially pure titanium and the titanium alloy (Ti-6Al-4V) are presented and briefly discussed. Samples of both commercially pure titanium and the Ti-6Al-4V alloy were prepared from the as-provided plate stock along both the longitudinal and transverse orientations. The specimens were then deformed to failure in uniaxial tension. The intrinsic influence of material composition and test specimen orientation on microstructure, tensile properties, and resultant fracture behavior of the two materials is presented. The conjoint influence of intrinsic microstructural features, nature of loading, and specimen orientation on tensile properties of commercially pure …

A Study Of Cyclic Fatigue, Damage Initiation, Damage Propagation, And Fracture Of Welded Titanium Alloy Plate, Tirumalai Srivatsan, Udaykar Bathini, Anil Patnaik, T. Quick

Anil Patnaik

In this paper, the influence of test specimen orientation and microstructure on cyclic stress-amplitude controlled fatigue response, damage initiation, damage propagation and fracture behavior of samples taken from a welded plate of titanium alloy is presented and discussed. Test specimens from the chosen alloy were prepared from an as-welded plate of the material with the stress axis both parallel (longitudinal) and perpendicular (transverse) to the deformed (rolling) direction of the plate. The test specimens were cyclically deformed at different values of maximum stress at a constant load ratio of 0.1, and the resultant cycles-to-failure was recorded. The fracture surfaces of …

The Fatigue Behavior Of Built-Up Welded Beams Of Commercially Pure Titanium, Anil Patnaik, Narendra Poondla, Udaykar Poondla, Tirumalai Srivatsan

Anil Patnaik

In this article, the results of a recent study aimed at evaluating, understanding, and rationalizing the extrinsic influence of fatigue loading on the response characteristics of built-up welded beams made from commercially pure titanium (Grade 2) are presented and discussed. The beams were made from welding plates and sheets of titanium using the pulsed gas metal arc welding technique to form a structural beam having an I-shaped cross section. The welds made for the test beams of the chosen metal were fillet welds using a matching titanium filler metal wire. The maximum and minimum load values at which the built-up …

Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan

Robert Y. Liang

A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …