Summer 2013 Research and Participants

Content Creation Methods for Interactive eBooks featuring computationally intensive applications

REU Student: John Angarita, Columbia University; Logan Collins (AERO-U REU), Texas A&M University

Faculty Mentor: Dr. Jacques Richard

In this project, we have sought to facilitate learning through the improvement of educational interactive technologies. The current eBooks in today’s market do not use current products such as the iPhone and Android to engage in interactive versions of plain books, so our objective has been to explore the best method to take advantage of such tools. By analyzing the pros and cons of eBook formats, such as Kindle Format 8 and iBooks, we have concluded that ePub provides the ease of use desired along with the capability of including intensive interactive materials. We then researched what products are best suited to work with the latest version of ePub, and we found iBooks and Gitden Reader to fully support ePub3. On the other hand, many other readers still use ePub2 but we feel the lack of demand, as of now, for interactivity in their eBooks provides little motivation for use of the newer format. The process of then creating the textbook was started by creating a sample chapter, through which we were able to test the easiest methods to create the book and the various interactive capabilities of the user. We have laid the groundwork for the ease in creation of new interactive eBooks that can soon be assessed for efficiency. 

Increasing Interfacial Shear Strength in Composites Using Polyacrylonitrile Nanofiber-Hybridized Carbon Fibers

REU Student: Cody X. Bucheger, Texas A&M University

Faculty Mentor: Dr. Mahomad Naraghi and Dr. John Whitcomb

Grad Student Mentor: Kamyar Ravaji

Lightweight structures are an important aspect in many industries, including aerospace engineering and wind energy. The key to having lightweight structures is to develop structural materials with improved specific strength and toughness. A way to increase these mechanical properties is to enhance the Interfacial Shear Strength (IFSS). In this study, the goal was to control the IFSS between the fiber and the epoxy matrix. The approach to this goal was to use hybrid composites made from Polyacrylonitrile (PAN) nanofiber-hybridized carbon fibers. The PAN nanofibers are hypothesized to act as an anchor inside the epoxy matrix increasing the IFSS. To this end, single carbon fiber (SCF) and hybrid carbon fiber (HCF) samples have been created and baseline fragmentation tests on the SCF samples have been run. Throughout this research, many challenges arose in creating both the SCF and the HCF samples and running the fragmentation tests. Future research will include performing fragmentation tests on the HCF samples, so that a comparison can be made to the SCF samples.

The Alignment of Carbon Nanofibers/Nanotubes via Applied Uniform Electric Fields

REU Student: Kyle D. Chapkin, Rice University

Faculty Mentors: Dr. Dimitris Lagoudas

Grad Student Mentor: Frank Gardea

The work investigated the effect of applying a uniform electric field, at varying frequencies, during the post curing process of a thermoset epoxy resin with inclusions of carbon nanofiber (CNF), carbon nanotubes (CNT), and CNF embedded with CNTs during the electrospinning process, to see the degree of alignment in the nanocomposites. The CNTs, CNFs, and CNT/CNFs were uniformly, but randomly, dispersed in an epoxy matrix and the effect of electric field frequency on the extent of alignment of the nanofibers/nanotubes was evaluated while holding voltage, time duration, and weight percent constant. In order to characterize the degree of alignment and dispersion of the CNTs and CNFs at different frequencies, optical microscopy, electrical conductivity, and thermal conductivity tests were performed.

It was found that the CNF and CNT/CNF composites show clear signs of nanoconstituent alignment in the matrix for all tested frequencies, which also resulted in an increase, by orders of magnitude, of the electrical conductivity. The CNT composites showed no visible sign of alignment regardless of the applied, however the percolation threshold was reached at the studied concentration. For all composite samples, the higher the applied frequency of the electric field, the greater the particle dispersion in the matrix and the smaller the size of the agglomerates. 

Characterization of Repetitively Pulsed Hypersonic Variable Mach Number Flow from PHACENATE

REU Student: Samuel Chen, The College of New Jersey

Faculty Mentors: Dr. Rodney Bowersox

Grad Student Mentor: Chi Mai

Studying hypersonic flow presents many challenges, and though there exist facilities capable of simulating hypersonic flow, common limiting factors are run time, cost of infrastructure, and sheer size considerations. In particular, the high speeds (greater than Mach 5) and short run times often necessitate specialized diagnostic techniques. Pulsed facilities provide duty cycles several orders of magnitude higher at a much lower operating cost when compared to traditional blow-down facilities and shock tunnels, and can additionally be small enough for tabletop operation. Such facilities can be extremely useful when considering laser diagnostics, allowing the use of alternative gases due to the much lower mass flow required for operation. The focus of this research was to construct and test a hypersonic facility, built around the Pulsed Hypersonic Adjustable Contour Expansion Nozzle for Aerothermochemical Testing (PHACENATE). Specifically, the steady-state, pulse-to-pulse, and spatial uniformity are of significance. This nozzle is designed to create pulsed, adjustable hypersonic flows ranging from Mach 5 to Mach 8, with the ultimate goal of studying the effects of mechanical and thermal non-equilibrium on turbulent flows using the new Vibrationally Excited Nitrous Oxide Monitoring (VENOM) laser diagnostic. The facility was successfully constructed, and initial test data indicates that the flow has good steady-state and pulse-to-pulse uniformity.

Experimental Investigation of Various Flow Field Diagnostic Techniques for Supersonic Applications

REU Student:  Samantha Gildersleeve, Roger Williams University

Faculty Mentor: Dr. Rodney Bowersox

The field of aerospace engineering is continuously approaching new limits as it utilizes cutting-edge technology and intelligence to advance society on a daily basis. The progression of this demanding realm of science and engineering is propelled by the ability to test theory with experimental models and computational analysis. At the National Aerothermochemistry Lab - High Speed Wind Tunnel (NAL-HSWT), a diverse group of undergraduate, graduate, post-doctoral, and faculty mentors work cohesively to uncover new questions, conclusions, and solutions for improving current technology. Wind tunnel testing provides a controlled environment used in aerodynamic research to study the effects of airflow moving over solid bodies. It is used to quantify the forces exerted on a body and simulate the aerodynamic effects. In the present study, the Mach 5 Supersonic High Reynolds Number wind tunnel (SHR), was assembled and used to investigate various flow field diagnostic techniques. The diagnostics included Background Oriented Schlieren (BOS), Particle Image Velocimetry (PIV), and Schlieren imaging. Each of which will facilitate optical methods of flow visualization for a high-speed, high Reynolds number, supersonic boundary layer. With visual analysis of airflow acting over a test model, boundary layer physics can be better understood and designs for optimal aerodynamic efficiency can be employed.

Fretting Wear Behavior of High-Performance Polymers

REU Student: Angel Montoya, University of Texas at Austin

Faculty Mentor: Dr. H.J. Sue

Grad Student Mentor:  Kevin Laux

Polymer materials have become popular solutions to many modern engineering problems. High performance polymers from the polyaryletherketone (PAEK) family are being selected for various applications due to their strong mechanical properties and resistance to most solvents. PAEKs, such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), are commonly chosen for extreme environment applications, but differentiating which polymer will perform the best in terms of wear is not straightforward. Experiments involving sliding wear have been conducted but it is difficult to separate the contributions of adhesive fatigue using such tests. The adhesive fatigue behavior is typically resulted from repeated small-range cyclical motion and is often referred to as fretting.  A polymer under a fretting environment will behave much differently than when experiencing traditional sliding motion. In this study, 6 PAEK polymers of varying molecular weights and crystallinity were tested under fretting conditions in order to determine material performance. Additionally, the surface of the polymers was examined after the completion of a wear test to gain insight on the wear mechanisms the polymers experience. The comparative wear data and analysis of debris generated has provided unique insight into adhesive fatigue behavior. This work will serve as a foundation for more robust modeling of polymer wear and debris formation.

Aeroelastic Response of a Wing to a Simulated Gust Via Gust Velocity Mapping

REU Student: Alexander Moyes, University of Michigan

Faculty Mentors: Dr. Thomas Strganac

Grad Student Mentor: Yogesh Babbar

This research studies experimental unsteady aeroelastic effects on wings. The research team’s goal is to be able to predict an unsteady flow, such as an atmospheric gust, ahead of an aircraft and adjust the control surfaces. Texas A&M currently has a wind tunnel with a 3 Foot x 4 Foot test section where a wing section is connected to a mechanism that allows the wing to plunge and pitch within the test section at a prescribed rate. As the flow goes over the wing section, vortex shedding occurs and the flow behind the wing section becomes turbulent, similar to an unsteady flow in the atmosphere. There is a second wing section that in the test section behind the current wing section. This wing has the typical degrees of freedom of a wing bending and twisting in the atmosphere. The overall goal is to have this unsteady flow interact with the second wing and analyze the aeroelastic effects from the unsteady flow.

The summer 2013 research supports analysis of the unsteady flow behind the front wing section. The key is developing a way to collect data to create a velocity map with respect to the flow direction and the aerodynamic forces. This involves designing, building and testing an automated traverse system to move a hot wire anemometer within the test section and collect velocity measurements. This was successfully automated for the primary flow direction and the hot wire was calibrated with the pitot tube to yield the velocity. The pitch and plunge of the wing helps create a pitch frequency. The research led to measurements of the gust flow velocities and present frequencies.

Assessment of Student Learning Using Active Engagement Tools in the Aerospace Engineering Curriculum & Evaluating and Developing Methods to Teach Large Engineering Classes

REU Student: Julio C. Perez, Edison State College

Faculty Mentor: Dr. Kristi Shryock

This work investigates a culmination of multiple instructional methods combined to create the Teaching Large Engineering Classrooms (TLEC) theory.   This theory incorporates interactive engagement tools in order to focus on the process of learning rather than the traditional method of final assessment grade as an indicator of learning. The goal is to provide a general theory applicable to any discipline in order to engage the student fully while successfully using the process of learning to develop self-sufficient students, in this case engineers. To further understand the impact of the TLEC theory, a short instrument to assess mathematics skills was developed.  Using a small sample of ten students with half of the sample from non-science majors, the researcher provided differentiated instruction to half of the sample with the other half serving as a control group and being given traditional instruction with no further direction. The differentiated instruction is based on the different learning styles by which students learn, each sample problem was explain by covering the auditory, kinesthetic, visual, and logical learning styles.  The researcher concluded the effectiveness of the TLEC theory was not necessarily shown through the number of correct answers the student received.  Differences were seen in the reflection assessment survey given to the participants in the form of a group and individual interviews. The group that received instruction was able to note thoroughly that their methods in finding an answer were flawed because of mistakes they made, comparing the process of attaining the answer to the instruction given. One of the key results of the study indicates that the process of learning is not necessarily noted on the number of correct answers the participants received, rather the learning came when the participants were asked to note what they did wrong and if they were able to fix it. The ultimate goal of the TLEC theory in simple terms is allowing students to learn and understand the process of learning without being focused on attaining a grade to indicate whether or not they learned. In addition, the theory should allow instructors to mainstream grades, retain students, gain higher passing rates, increase motivation and participation, and integrate interactive engagement tools into the classroom curriculum.  

Functionality of a Supersonic Wind Tunnel

REU Student: William Timothy Rogers, Texas A&M University

Faculty Mentor: Dr. Rodney Bowersox

There is an increasing desire for transport aircraft that operate in the supersonic realm of flight for both commercial and defense applications. Although these types of aircraft can be built now, they are not aerodynamically efficient enough leading to large amounts of drag and thus, large operating costs. A significant reason for the drag caused is that several aspects of high speed flow physics are not currently well understood.  In order to further increase the understanding experiments are planned to look at the feasibility of flow control through energy deposition techniques. However, before these experiments can take place, the Supersonic High Reynolds number (SHR) wind tunnel at the National Aerothermochemistry Lab at Texas A&M University required reassembly after an expansion of the facility.  As part of the reassembly process tubing for all of the pressure gauges and control lines needed redoing, long with all of the electrical for the control box of the tunnel.  In addition to the smaller lines, a large, steel-braided hose was attached to the settling chamber as the air supply and a muffler after the diffuser.  Each piece of the tunnel was then put back in place and resealed for operational testing of the wind tunnel. Testing of the tunnel’s ability to run was done using the Mach 5 nozzle and was deemed successfully after starting the tunnel with a Mach number of 4.78, which was close to previous tunnel readings. With tunnel reassembly complete, the planned experiments can commence.

Parameter Identification of Embedded Shape Memory Alloy Particles for Damage Detection

REU Student: William D. Whitten, Texas A&M University

Faculty Mentors: Dr. Darren Hartl

Grad Student Mentor: Edwin Alexander Peraza Hernandez

Engineers have been using the unique behavior of shape memory alloys (SMAs) to create novel solutions to engineering problems for several decades. One of the alloy’s characteristics, known as pseudoelasticity, is of particular interest to those investigating SMA sensing applications. Researchers are attempting to embed SMA particles inside an aluminum matrix to act as damage sensors. If cracks form in the matrix, the particles in the location of stress concentrations will undergo a stress-induced phase transformation. This phase transformation from austenite to martensite is monitored using acoustic emission. By embedding these particles in structural components, the safety of these structures could be closely monitored without visual inspection or destructive testing. A finite element model of the particles would allow the experimental configuration to be optimized; however, the SMA material parameters must be known before an accurate model can be created. This work describes the use of experimental digital image correlation results, finite element analysis, and numerical optimization methods to identify the material parameters of the SMA particles. The 3-month investigation has shown that optimization methods can be used to predict the material parameters of shape memory alloys using data taken from multiple types of experiments. 

Effect of pH Variance on Properties of Layer-by-Layer Assembled Chitosan and Poly (acrylic acid) Pervaporation Membranes

REU Student: Travis Wilson, University of Texas at El Paso

Faculty Mentors: Dr. Jaime Grunlan

Grad Student Mentor: Ping Tzeng

Polymer membranes were assembled  using the polyelectrolytes chitosan (CH) and poly(acrylic acid) (PAA) for application in pervaporation methods. Interest in CH/PAA membranes has been shown in pervaporation for the separation of water and alcohol solutions. The layer-by-layer technique was used to deposit the individual layers of the chitosan and PAA, which are considered together as bilayers. The focus of this study was the effect of the pH of PAA on membrane characteristics and pervaporation performance. The CH/PAA membranes were fabricated at pH 5.5 for CH and ph 3.0, 3.5, 4.0 and 5.0 for PAA. The thickness of each sample was measured using ellipsometry and profilometry, showing an increasing trend with the increase of pH. This trend matched well with the quartz crystal microbalance (QCM) data for the mass growth of the membrane. These trends correlate with the concept of polymer configuration dependency and interdiffusion on charge density. Differential scanning calorimetry was used to find the glass transition temperature of the membranes, which describes the degree of interaction between CH and PAA. Pervaporation testing is to be conducted on the membranes to quantify permeate flux and selectivity for alcohol dehydration. A brief mention of continued work for the pervaporation of water/alcohol solutions concludes this study.