Engineering Commons^™

A High-Pressure Shear Testing Approach To Measure Flow Stresses Near A Friction Stir Welding Tool, David Prymak, Michael Miles, Tracy W. Nelson, Fredrick Michael

Faculty Publications

A new approach for measuring flow stresses near a spinning friction stir welding (FSW) tool is evaluated on AA 6061-T6 plate. The test consists of plunging a cylindrical tool with a flat face into the plate at different rotational speeds, using a variety of constant vertical loads. A viscosity-based model of the shear layer created under the tool is employed to estimate local flow stresses. The flow stresses measured by this approach exhibited an inverse relationship with temperature and a positive dependence on the pressure imposed by the spinning flat-faced tool. Compared to hot compression and hot torsion results, estimated …

Correlation Of Segmental Lumbar Kinematics With A Wearable Skin Strain Sensor Array, Andrew Gibbons, Paul Mcmullin, Joseph Peterson, Spencer Baker, Kelly Clingo, Ulrike H. Mitchell, David T. Fullwood, Anton E. Bowden

Student Works

Introduction: Joint kinematics have been shown to be strongly diagnostic of underlying pathology in the knee, hip, shoulder, and ankle. However, the anatomical complexity of the spine has made obtaining accurate, segmental kinematics extremely challenging. Current approaches required specialized hardware (e.g., a dual x-ray system), or are highly invasive (e.g., bone pins implanted into the vertebrae). Recently, our lab has developed a wearable array of skin-mounted strain sensors that hopes to address this challenge. The purpose of the present work study was to quantify the utility of this array through comparison with real-time lumbar vertebral kinematics.

Materials and Methods: A …

Vacuum Infusion Of Composites: Durability Of Hybrid Large Area Additive Tooling For Vacuum Infusion Of Composites, Nathan Northrup, Jason Weaver, Andy R. George

Faculty Publications

The durability of a hybrid large area additively manufactured fiberglass ABS mold for vacuum infusion of composites was evaluated. The validation was done by designing and fabricating a mold for a custom test artifact and analyzing the surface geometry over the course of multiple infusions until tool failure. After printing and machining, the mold required a sealer to maintain vacuum integrity. The mold was able to produce 10 parts successfully before the sealed tool surface began to tangibly roughen, resulting in increased difficulty of demolding and a rougher surface finish. After the 14th infusion, the part required destructive force to …

Reliable Mode Tracking In Gradient-Based Optimization Frameworks With Flutter Constraints, Taylor Mcdonnell, Andrew Ning

Faculty Publications

In order to construct mode-specific flutter constraints for use in gradient-based multidisciplinary design optimization frameworks, mode tracking must be used to associate the current iteration’s modes with the modes corresponding to each constraint function. Existing mode tracking methods, however, do not provide a method by which to ensure the accuracy of mode associations, making them unsuitable for use in situations where obtaining correct mode associations is critical. To remedy this issue, a new mode tracking method is presented which incorporates backtracking logic in order to maintain an arbitrarily high degree of confidence in mode correlations during gradient-based optimization and/or during …

Using Blade Element Momentum Methods With Gradient-Based Design Optimization, Andrew Ning

Faculty Publications

Blade element momentum methods are widely used for initial aerodynamic analysis of propellers and wind turbines. A wide variety of correction methods exist, but common to all variations, a pair of residuals are converged to ensure compatibility between the two theories. This paper shows how to rearrange the sequence of calculations reducing to a single residual. This yields the significant advantage that convergence can be guaranteed and to machine precision. Both of these considerations are particularly important for gradient- based optimization where a wide variety of atypical inputs may be explored, and where tight convergence is necessary for accurate derivative …

A Comparison Of Aerodynamic Models For Optimizing The Takeoff And Transition Of A Bi-Wing Tailsitter, Ryan Anderson, Jacob Willis, Jacob Johnson, Andrew Ning, Randal Beard

Faculty Publications

Electric vertical takeoff and landing (eVTOL) aircraft take advantage of distributed electric propulsion as well as aerodynamic lifting surfaces to take off vertically and perform long-duration flights. Complex aerodynamic interactions and a hard-to-predict transition maneuver from hover to wing-borne flight are one challenge in their development. To address this, we compare three different interaction models of varying fidelity for optimizing the transition trajectory of a biplane tailsitter. The first model accounts for simplified rotor-on-wing interactions using momentum theory, while the other two account for wing-on-wing interactions using a vortex lattice method and rotor-on-wing aerodynamic interactions using blade element momentum theory. …

User Guide For Dust Modeling Using Cmaq 5.3.1 And Wrf 4.2.1, Zachary D. Lawless, Ariel S. Cable, Cameron B. Van Dyke, Bradley R. Adams

Faculty Publications

Researchers at Brigham Young University (BYU) have developed a software framework for modeling dust emission and transport using the Community Multiscale Air Quality (CMAQ) modeling system in conjunction with the Weather Research and Forecasting (WRF) model and other utility programs. This framework uses meteorological data, land use data, and soil properties to predict dust concentrations for a specified area. This User Guide describes the start-to-finish process required to install and utilize relevant software to calculate and visualize dust concentrations. Note that the examples and figures provided in the guide are specific to Utah in the western United States, where this …

Optimization Of Turbine Tilt In A Wind Farm, James Cutler, Andrew P.J. Stanley, Jared J. Thomas, Andrew Ning

Faculty Publications

Wind farm power production is significantly affected by upstream turbines creating wakes of slower wind speeds that overlap the rotor swept areas of downstream turbines. By optimizing the tilt angle of the turbines in a farm, wakes may be deflected away from downstream turbines, increasing the overall energy production. In this study, we optimized the tilt angle of turbines in a wind farm to maximize energy production. We used an analytic wake model modified for gradient-based optimization to consider wake deflection from tilt. We considered optimizing the tilt angle of each turbine assuming that it remained fixed for the lifetime …

Reducing Wind Farm Power Variance From Wind Direction Using Wind Farm Layout Optimization, Bertelsen Gagakuma, Andrew P.J. Stanley, Andrew Ning

Faculty Publications

This paper investigates reducing power variance caused by different wind directions by using wind farm layout optimization. The problem was formulated as a multi-objective optimization. The ε−constraint method was used to solve the bi-objective problem in a two-step optimization framework where two sequential optimizations were performed. The first was maximizing the mean wind farm power alone and the second was minimizing the power variance with a constraint on the mean power. The results show that the variance in power estimates can be greatly reduced, by as much as 30%, without sacrificing mean plant power for the different farm sizes and …