29 Jun 2021

Rough River Outlet Works Physical Model Study

Abstract: The US Army Corps of Engineers, Louisville District, requested the support and assistance of the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), in the evaluation of the hydraulic performance of the replacement Outlet Works for Rough River Dam. To support the design effort, CHL constructed a 1:25.85 scale physical model. The proposed features of the model in the domain are the curved approach channel, intake structure, transition, curved conduit, stilling basin, concrete apron, and retreat channel. Tests performed to evaluate the hydraulic performance illuminated a few design concerns. To address these issues, several key design changes were made. These included the retreat channel slope, end sill design, and transition design.

28 Jun 2021

Complex Network Analysis for Early Detection of Failure Mechanisms in Resilient Bio-structures

Abstract: Bio-structures owe their remarkable mechanical properties to their hierarchical geometrical arrangement as well as heterogeneous material properties. This dissertation presents an integrated, interdisciplinary approach that employs computational mechanics combined with flow network analysis to gain fundamental insights into the failure mechanisms of high performance, light-weight, structured composites by examining the stress flow patterns formed in the nascent stages of loading for the rostrum of the paddlefish. The data required for the flow network analysis was generated from the finite element analysis of the rostrum. The flow network was weighted based on the parameter of interest, which is stress in the current study. The changing kinematics of the structural system was provided as input to the algorithm that computes the minimum-cut of the flow network. The proposed approach was verified using two classical problems three- and four-point bending of a simply-supported concrete beam. The current study also addresses the methodology used to prepare data in an appropriate format for a seamless transition from finite element binary database files to the abstract mathematical domain needed for the network flow analysis. A robust, platform-independent procedure was developed that efficiently handles the large datasets produced by the finite element simulations. Results from computational mechanics using Abaqus and complex network analysis are presented.

25 Jun 2021

Rotor Blade Design Framework for Airfoil Shape Optimization with Performance Considerations

Abstract: A framework for optimizing rotor blade airfoil shape is presented. The framework uses two digital workflows created within the Galaxy Simulation Builder (GSB) software package. The first is a workflow enabling the automated creation of a surrogate model for predicting airfoil performance coefficients. An accurate surrogate model for the rapid generation of airfoil coefficient tables has been developed using linear interpolation techniques that is based on C81Gen and ARC2D CFD codes. The second workflow defines the rotor blade optimization problem using GSB and the Dakota numerical optimization library. The presented example uses a quasi-Newton optimization algorithm to optimize the tip region of the UH-60A main rotor blade with respect to vehicle performance. This is accomplished by morphing the blade tip airfoil shape for optimum power, subject to a constraint on the maximum pitch link load.

25 Jun 2021

A Physics-Informed Neural Network for Sound Propagation in the Atmospheric Boundary Layer

Abstract: We describe what we believe is the first effort to develop a physics-informed neural network (PINN) to predict sound propagation through the atmospheric boundary layer. PINN is a recent innovation in the application of deep learning to simulate physics. The motivation is to combine the strengths of data-driven models and physics models, thereby producing a regularized surrogate model using less data than a purely data-driven model. In a PINN, the data-driven loss function is augmented with penalty terms for deviations from the underlying physics, e.g., a governing equation or a boundary condition. Training data are obtained from Crank-Nicholson solutions of the parabolic equation with homogeneous ground impedance and Monin-Obukhov similarity theory for the effective sound speed in the moving atmosphere. Training data are random samples from an ensemble of solutions for combinations of parameters governing the impedance and the effective sound speed. PINN output is processed to produce realizations of transmission loss that look much like the Crank-Nicholson solutions. We describe the framework for implementing PINN for outdoor sound, and we outline practical matters related to network architecture, the size of the training set, the physics-informed loss function, and challenge of managing the spatial complexity of the complex pressure.

24 Jun 2021

Helicopter Rotor Blade Multiple-Section Optimization with Performance Considerations

Abstract: This paper presents advancements in a surrogate-based, rotor blade design optimization framework for improved helicopter performance. The framework builds on previous successes by allowing multiple airfoil sections to designed simultaneously to minimize required rotor power in multiple flight conditions. Rotor power in hover and forward flight, at advance ratio 𝜇 = 0.3, are used as objective functions in a multi-objective genetic algorithm. The framework is constructed using Galaxy Simulation Builder with optimization provided through integration with Dakota. Three independent airfoil sections are morphed using ParFoil and aerodynamic coefficients for the updated airfoil shapes (i.e., lift, drag, moment) are calculated using linear interpolation from a database generated using C81Gen/ARC2D. Final rotor performance is then calculated using RCAS. Several demonstrative optimization case studies were conducted using the UH-60A main rotor. The degrees of freedom for this case are limited to the airfoil camber, camber crest position, thickness, and thickness crest position for each of the sections. The results of the three-segment case study show improvements in rotor power of 4.3% and 0.8% in forward flight and hover, respectively. This configuration also yields greater reductions in rotor power for high advance ratios, e.g., 6.0% reduction at 𝜇 = 0.35, and 8.8% reduction at 𝜇 = 0.4.

23 Jun 2021

Historic Landscape Management Plan for the Fort Huachuca Historic District National Historic Landmark and Supplemental Areas

Abstract: The U.S. Congress codified the National Historic Preservation Act of 1966 (NHPA) to provide guidelines and requirements for preserving tangible elements of our nation’s past. This preservation was done primarily through creation of the National Register of Historic Places (NRHP), which contains requirements for federal agencies to address, inventory, and evaluate their cultural resources, and to determine the effect of federal undertakings on properties deemed eligible or potentially eligible for the NRHP. This work inventoried and evaluated the historic landscapes within the National Landmark District at Fort Huachuca, Arizona. A historic landscape context was developed; an inventory of all landscapes and landscape features within the historic district was completed; and these landscapes and features were evaluated using methods established in the Guidelines for Identifying and Evaluating Historic Military Landscapes (ERDC-CERL 2008) and their significance and integrity were determined. Photographic and historic documentation was completed for significant landscapes. Lastly, general management recommendations were provided to help preserve and/or protect these resources in the future.

23 Jun 2021

Meteorological Property and Temporal Variable Effect on Spatial Semivariance of Infrared Thermography of Soil Surfaces for Detection of Foreign Objects

Abstract: The environmental phenomenological properties responsible for the thermal variability evident in the use of thermal infrared (IR) sensor systems is not well understood. The research objective of this work is to understand the environmental and climatological properties contributing to the temporal and spatial thermal variance of soils. We recorded thermal images of surface temperature of soil as well as several meteorological properties such as weather condition and solar irradiance of loamy soil located at the Cold Regions Research and Engineering Lab (CRREL) facility. We assessed sensor performance by analyzing how recorded meteorological properties affected the spatial structure by observing statistical differences in spatial autocorrelation and dependence parameter estimates.

17 Jun 2021

Application of Laser Induced Breakdown Spectroscopy (LIBS) for Environmental, Chemical, and Biological Sensing

Abstract: The Army is interested in sensors capable of characterizing/monitoring the environment (battlefield or military training ranges) at proximal distances. Recently, we evaluated laser induced breakdown spectroscopy (LIBS) systems (hand-held, proximal, and bench top) for the characterization of metals (antimony, copper, lead, tungsten, and zinc) in soils obtained from military training ranges. We then compared the results to findings obtained with standard field and laboratory instrumentation for metals analysis - X-ray Fluorescence (XRF) and Inductively Couple P28lasma- Optical Emission Spectroscopy (ICP-OES).

16 Jun 2021

Field Measurement and Monitoring of Hydrodynamic and Suspended Sediment within the Seven Mile Island Innovation Laboratory, New Jersey

Abstract: The Seven Mile Island Innovation Laboratory (SMIIL) was launched in 2019 to evaluate beneficial use of dredge material management practices in coastal New Jersey. As part of that effort, the Philadelphia District requested that the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, collect data to characterize the hydrodynamics and turbidity within the central portions of the SMIIL prior to and during dredge material placement. Pre-dredge monitoring found that apart from punctuated wind events, the study area waters were generally calm and clear with small waves, <0.25 m, slow current speeds (~0.1 m/s), low turbidity (~10 ntus), and low suspended sediment concentrations (~10–20 mg/L). In March 2020, 2,475 m3 of dredged sediment was placed on the northern portion of Sturgeon Island within the SMIIL. Turbidity in the waters surrounding the island was monitored to quantify extent of the sediment plume resulting from the placement. Observations found little to no turbidity plume associated with the dredging operations beyond 20 m from the island and that the plume was largely limited to areas near a tidal creek draining the placement area. Additionally, turbidity levels quickly returned to background conditions at times when the dredge was not in operation.

15 Jun 2021

Red River Structure Physical Model Study: Bulkhead Testing

Abstract: The US Army Corps of Engineers, St. Paul District, and its non-federal sponsors are designing and constructing a flood risk management project that will reduce the risk of flooding in the Fargo-Moorhead metropolitan area. There is a 30-mile long diversion channel around the west side of the city of Fargo, as well as a staging area that will be formed upstream of a 20-mile long dam (referred to as the Southern Embankment) that collectively includes an earthen embankment with three gated structures: the Diversion Inlet Structure, the Wild Rice River Structure, and the Red River Structure (RRS). A physical model has been constructed and analyzed to assess the hydraulic conditions near and at the RRS for verification of the structure’s flow capacity as well as optimization of design features for the structure. This report describes the modeling techniques and instrumentation used in the investigation and details the evaluation of the forces exerted on the proposed bulkheads during emergency operations for the RRS.