To know how to evoke enthusiasm is the art of teaching.
Henri-Frederic Amiel (1821-1881, Swiss author)
Curiosity comes naturally to students, and I believe the most effective teacher is one who can guide this curiosity to help students develop understanding. My philosophy on how to best inspire and utilize this curiosity has three complimentary components: connect with students through their individual interests and learning style; provide professional and academic context for the course content they are learning; and use an explicit and transparent framework to support their learning development. To implement this philosophy, I have employed a number of evidence-based strategies and techniques to continually improve my teaching outcomes.
I am an aerospace engineer with experience developing smart materials and structures from fundamental principles to functional devices. My experience is in structural dynamics and engineering design, mechanics of solids and fluids, and occupant protection using semi-active or “smart” devices. I am developing research programs focusing on the following three areas: 1) Smart composite material systems for occupant protection and wearable augmentation; 2) Advanced manufacturing of smart structures and functionalized materials; 3) Applications of the above for improving human-device interfaces.
The use of multifunctional materials in so-called “smart structures” is a trend that is gaining adoption outside of what have historically been highly specialized applications, such as cutting edge aerospace components or custom biomimetic/biocompatible devices. At the same time, the demands of widespread availability – namely cost, volume, and repeatability – require process modeling and materials characterization capabilities that are challenging to scale from laboratory prototypes to production applications.
I am an aerospace engineer with experience developing smart materials and structures from fundamental principles to functional devices. My experience is in structural dynamics and engineering design, mechanics of solids and fluids, and occupant protection using semi-active or “smart” devices. I am developing research focusing on the following three areas: 1) Smart composite material systems for occupant protection and wearable augmentation; 2) Advanced manufacturing of smart structures and functionalized materials; 3) Applications of the above for improving human-device interfaces.
- Structural dynamics
- Composite materials
- Smart materials and structures
- Structural control using smart fluid devices
- Human factors in spaceflight
- Launch and entry vehicle design
- Additive manufacturing technologies
- Innovations in STEM education
Smart composite material systems for occupant protection and wearable augmentation
Human occupants inside aerospace systems are often not only the most delicate system components, but also the most diverse. Ensuring the health and safety of a wide range of occupant physiologies without overburdening the rest of the vehicle with conservative – and costly – design decisions requires a unique approach. In this area, so-called “smart” composite material systems which change their properties in response to the vehicle’s dynamic environment and occupant characteristics have been shown to be effective design resources.
Semi-Active Energy Absorbers for Occupant Protection
We developed several smart fluid energy absorbers for land, sea, air and space vehicles [CP-12]*. These devices employ magnetorheological (MR) fluid, a suspension of iron particles in oil which responds to an applied magnetic field by changing from a fluid to a solid. MR energy absorbers are therefore capable of tuning their force-velocity response to an optimal profile, e.g. minimizing force transmitted during crash events, or attenuating seat vibration across a wide range of occupant masses. We also were first to demonstrate mixed-mode operation at conditions representing practical dampers. Dubbed “squeeze strengthening”, this technique nearly doubled the force output, and would allow for a much more compact and mass efficient device [JA-6]. I have one patent application covering this work, submitted Fall 2015, currently in the final stages of examination.
Advanced manufacturing of functionalized materials and structures
The explosion of 3D printing methods is rapidly changing the possible ways structures and subsystems can be developed and combined into functionalized systems. Techniques like automated fiber placement in composites manufacturing must be coupled with intensive inspection and verification methods to overcome operation uncertainty and ensure reliability. Novel materials and combination options must keep pace, so precise predictions of the influence manufacturing processes have on finished materials will be vital for fully leveraging this promising technology.
Wide-ranging Nondimensional Modeling and Characterization of Fluid Composites
Our work showed that the bulk behavior of MR fluids depends on microscale interaction effects between the carrier fluid and suspended particles by connecting Bingham number and Mason number nondimensional descriptions, respectively at the macro- and microscale [JA-4]. We also successfully applied Mason number, a nondimensionalization technique based on particle-fluid interaction effects, to model MR energy absorber force vs. velocity behavior at the highest shear rates reported in modern literature and representing practical device operating conditions [JA-5]. Furthermore, we showed that a wide variety of operating speeds, temperatures, and applied magnetic fields can be reduced to a single master curve based on this parameter nondimensionalization [JA-3], and that this method is a practical design tool [JA-1].
Applications for improving human-device interfaces
Interfaces between human users and electromechanical systems have historically been plagued by incompatibility issues with respect to structural impedance matching, sensing resolution, and power density. By blending controllable device elements with the customizability offered by additive manufacturing methods, these challenges can be overcome to provide a diverse set of users with restored or expanded capability. Whether through a custom-fit prosthetic socket insert that matches the wearer’s physiology, or a more intuitive control method for robotic teleoperation, the fusion of smart materials and tailor-made functional structures will realize a major paradigm shift in engineering design.
Accomplishments ExoHand: Custom Fit Composite Interface Device with Embedded Sensing
The MGA (Maryland, Georgetown, Army) Exoskeleton is a telerobotic platform that provided the opportunity for proof-of-concept studies on ExoHand, our intuitive interface for user control of the robotic end effector. We designed a “glove”, which was completely 3D printed from multiple materials and sized to fit the finger segment lengths of the test user. By combining a flexible thermoplastic polyurethane (TPU) with a graphite-based conductive filament, we created a network of piezoresistive sensors embedded within the device. By measuring resistance through the ExoHand circuit, we were able to back out finger joint position and use this signal to control the robot grip.
*Citations refer to items listed in publications, where 'CP' indicates published conference proceedings, and 'JA' indicates peer-reviewed journal articles.
- ENAE283/H – Introduction to Aerospace Systems: Introduction to airplanes and space vehicles as aerospace systems. Fundamentals that describe these systems. Elements of aerodynamics, airfoils and wings. Airplane performance, stability and control. Aircraft and rocket propulsion. Fundamentals of orbital motion. Aspects of vehicle conceptual design.
- ENAE423 – Vibrations and Aeroelasticity: Dynamic response of single and multiple degrees of freedom systems, finite element modeling, wing divergence, aileron reversal, wing and panel flutter.
- ENAE425/ENAE654/ENME672 – Mechanics of Composite Structures: Introduction to structures composed of composite materials and their applications in aerospace. In particular, filamentary composite materials are studied. Material types and fabrication techniques, material properties, micromechanics, anisotropic elasticity, introduction to failure concepts.
- ENAE464 – Aerospace Engineering Laboratory: Application of fundamental measuring techniques to measurements in aerospace engineering. Includes experiments in aerodynamics, structures, propulsion, flight dynamics and astrodynamics. Correlation of theory with experimental results.
- ENAE483/ENAE484/ENAE788D – Space Systems Design: Senior capstone design course in the space track. Group preliminary design of a space system, including system and subsystem design, configuration control, costing, risk analysis, and programmatic development. Course also emphasizes written and oral engineering communications.
Other courses I have taught or am prepared to teach
- HONR248B/ENES269G – Topics in Grand Challenges in Engineering: Engineering the Tools of Discovery in Munich, Germany: A two-week intensive study abroad experience in Munich, Germany for entering freshmen UMD students. Alongside visits to local industry and universities, students complete a technical design proposal for an aerospace vehicle and mission concept, most recently an aerial robot for surveying Mars.
- ENAE324 – Aerospace Structures: Analysis of torsion, beam bending, plate bending, buckling and their application to aerospace vehicles.
- ENAE301 – Dynamics (Teaching Assistant): Kinematics and dynamics of three dimensional motion of point masses and rigid bodies with introduction to more general systems. Primary emphasis on Newtonian methods. Practice in numerical solutions and computer animation of equations of motion using MATLAB.
- ENAE414 – Aerodynamics II (Teaching Assistant): Aerodynamics of inviscid incompressible flows. Aerodynamic forces and moments. Fluid statics/buoyancy force. Vorticity, circulation, the stream function and the velocity potential. Bernoulli's and Laplace's equations. Flows in low speed wind tunnels and airspeed measurement. Potential flows involving sources and sinks, doublets, and vortices. Development of the theory of airfoils and wings.
- ENAE441 – Space Navigation and Guidance: Principles of navigation. Celestial, radio, and inertial navigation schemes. Navigational and guidance requirements for orbital, planetary, and atmospheric entry missions. Fundamentals of communications and information theory. Link budgets, antennas and telemetry systems.
- ENAE499* – Undergraduate Elective Research: Mentoring of one undergraduate student working to develop a computer numerical controlled (CNC) filament winding machine for the automated production of pneumatic artificial muscles.
- Structural Design Optimization Methods
- Finite Element Methods
- Smart Structures and Materials
- A.C. Becnel, N.M. Wereley, (2017). “Using Mason Number to Predict MR Damper Performance from Limited Test Data.” AIP Advances, 7(5).http://dx.doi.org/10.1063/1.4977226
- N.L. Golinelli, A.C. Becnel, A. Spaggiari, and N.M. Wereley (2016). “Experimental Characterization of Magnetorheological Fluids Using a Custom Searle Magnetorheometer: Influence of the Rotor Shape.” IEEE Transactions on Magnetics, 52(7).http://dx.doi.org/10.1109/TMAG.2016.2515983
- S.G. Sherman*, L.A. Powell, A.C. Becnel*, and N.M. Wereley (2015). “Scaling Temperature Dependent Rheology of Magnetorheological Fluids.” Journal of Applied Physics. 117(7).http://dx.doi.org/10.1063/1.4918628
- S.G. Sherman*, A.C. Becnel*, and N.M. Wereley (2015). “Relating Mason Number to Bingham Number in Magnetorheological Fluids.” J. Magnetism and Magnetic Materials. 380:98-104. http://dx.doi.org/10.1016/j.jmmm.2014.11.010
- A.C. Becnel*, S.G. Sherman*, W. Hu, and N.M. Wereley (2015). “Nondimensional Scaling of Magnetorheological Rotary Shear Mode Devices Using the Mason Number.” J. Magnetism and Magnetic Materials. 380:90-97.http://dx.doi.org/10.1016/j.jmmm.2014.10.049
- A.C. Becnel*, S.G. Sherman*, W. Hu and N.M. Wereley (2015). “Squeeze Strengthening of Magnetorheological Fluids Using Mixed Mode Operation.” Journal of Applied Physics. 117(7):17C706.http://dx.doi.org/10.1063/1.4907603
- A.C. Becnel*, W. Hu and N.M. Wereley (2014). “Mason Number Analysis of a Magnetorheological Fluid Based Rotary Energy Absorber.” IEEE Transactions on Magnetics. 50(11):4600704.http://dx.doi.org/10.1109/TMAG.2014.2327634
- A.C. Becnel*, W. Hu and N.M. Wereley (2012). “Measurement of Magnetorheological Fluid Properties at Shear Rates of up to 25,000 s-1.” IEEE Transactions on Magnetics. 48(11):3525-3528,http://dx.doi.org/10.1109/TMAG.2012.2207707
- A.C. Becnel, G.J. Hiemenz, and N.M. Wereley (2015). “Compact Magnetorheological Energy Absorbers for Adaptive Crew Seat Suspensions.” 45th International Conference on Environmental Systems, July 12-15, 2015, Bellevue, WA.https://repositories.tdl.org/ttu-ir/handle/2346/64539
- A. Becnel and N.M. Wereley (2013). “Demonstration of combined shear and squeeze strengthening modes in a Searle-type magnetorheometer.” ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems, September 16-18, Snowbird, UT.http://dx.doi.org/10.1115/SMASIS2013-3244
- A.C. Becnel, W. Hu and N.M. Wereley (2012). “High shear rate characterization of magnetorheological fluids.” Proceedings of the 2012 SPIE Active and Passive Smart Structures and Integrated Systems Conference, Vol. 8341, 834100http://dx.doi.org/10.117/12.916086.
- A.C. Becnel, W. Hu, G. Ngatu and N.M. Wereley (2011). “Magnetorheological fluid composites for crashworthiness applications.” 12th Japan International SAMPE Symposium, Nov. 9-11, 2011, Tokyo, Japan.
- A.C. Becnel, W. Hu, G.J. Hiemenz, and N.M. Wereley (2010). “Design and testing of a magnetorheological damper to control both vibration and shock loads for a vehicle crew seat.” SPIE Conference on Active and Passive Smart Structures and Integrated Systems, San Diego, CA, Vol. 7643.http://dx.doi.org/10.1117/12.848724
Other Scholarly Publications
- A.C. Becnel, NDSEG Fellow. Ph.D. Thesis. “High Strength Semi-Active Energy Absorbers Using Shear- And Mixed-Mode Operation At High Shear Rates.” May 2014.http://drum.lib.umd.edu/handle/1903/15464
- A.C. Becnel, M.S. Scholarly Paper: “Design and Testing of a Magnetorheological Damper to Control Both Vibration and Shock Loads for a Vehicle Crew Seat.” Dec. 2010. Continued in Ph.D. program.
- A.C. Becnel, NASA Academy Research Assistantship. Constellation Satellite Configurations for the Global Precipitation Measurement Program. Poster presented at Goddard Space Flight Center, August 2007.
- A.C. Becnel, E.L. Lopez- Oña, B. Herricks, B. Mason. K. Reichert. (Fall 2006). “WidgetWorks, an educational board game designed to interest 3rd-6th grade students in science and engineering fields.” Developed as an independent study group project, presented at the American Society of Engineering Educators global colloquium in Rio De Janeiro, Brazil.
Other professional society fellows
- Society for the Advancement of Materials and Process Engineering (SAMPE) - Chair, Baltimore-Washington Regional Chapter
Institute of Electrical and Electronics Engineers (IEEE)
American Society of Mechanical Engineers (ASME)
American Institute of Aeronautics and Astronautics (AIAA)
American Helicopter Society (AHS)