USMA Athena

USMA Athena is a secure digital service managed by the United States Military Academy Library to make the work of USMA scholars freely available, while also ensuring these resources are organized to preserve the legacy of USMA scholarship. The mission of USMA Athena is to showcase the academic impact and intellectual capital that has become synonymous with the celebrated heritage of educational prowess attributed to the Long Gray Line. Scholarship submitted to USMA Athena benefits from added visibility and discoverability via Google Scholar in addition to the use of persistent URLs that will provide enduring access to the work over time.


Recent Submissions

Military Power Reimagined: The Rise and Future of Shaping
(National Defense University Press: Joint Force Quarterly, 2021) Wolfley, Kyle J.
The belief that the U.S. military finds itself in a “complex environment”—one in which conventional war is rare, but Great Power competition has returned, coupled with the persistent threat of violent nonstate actors—is so commonplace that it can now be considered a truism. The United States, China, and Russia are engaged in a security competition below the threshold of open violence, yet scholars and practitioners struggle to articulate how these states’ militaries attempt to achieve their goals through ways other than warfighting or coercion. This article better conceptualizes a type of military operation that is often misunderstood and understudied and that has the potential to become one of the most frequent tools of interstate competition in the coming decades.
Making Connections: Ensuring Strength of the Civil Engineering Curriculum
(ASEE Conferences, 2022) Bruhl, Jakob C.
A fundamental structural design philosophy is to make connections stronger than the elements they connect. The same must be true within engineering education: the connections between concepts and courses must be stronger (or at least as strong) as the content learned. Teachers are encouraged to create structure for new knowledge, sometimes referred to as scaffolding. This scaffolding, much like shoring for a reinforced concrete building, can only be safely removed when the knowledge structure created by the student has gained sufficient strength, including connection strength. An inability to recall previously learned knowledge is a symptom of an underlying problem: a lack of effective understanding of engineering concepts and principles to then see their application in a new context. In other words, the connections between concepts and applications are weak. To address this underlying problem, civil engineering students at the US Military Academy at West Point were required to solve review problems on each homework assignment in two civil engineering design courses. This paper describes the theoretical underpinnings of these assignments and their implementation. Assessment includes three semesters of academic performance, time spent outside of class, student feedback, and teacher observations.
Market Competitive Electrolysis in ERCOT
(University of Texas, 2021) Deetjen, Thomas A.; Rhodes, Joshua D.; Hebner, Robert E.; Lewis, Michael C.; Davidson, F. Todd; Lloyd, Alan C.
Across US and global markets, demand for hydrogen is increasing. Simultaneously, the cost of producing hydrogen via electrolysis using electricity is decreasing, creating new market opportunities for this low-carbon hydrogen production process. To assess this opportunity, three key cost factors for hydrogen production using an electrolyzer need to be considered: capital, operating, and electricity cost. Of these three, the electricity cost can be assumed to vary most widely by location due to local availability of generating sources and local market rate structures. Although conventional wisdom holds that electrolyzers can only operate profitably if given very low electricity prices, this paper highlights an existing electricity market where electrolysis could be an attractive and profitable option for hydrogen production today. Since electricity prices vary over time, an electrolysis facility can choose when and to what extent to adjust its hydrogen production to target lower electricity prices and consequently reduce its hydrogen production costs. This white paper uses historical electricity price data from the Electric Reliability Council of Texas (ERCOT), the grid that serves 90% of Texas, coupled with a basic techno-economic model of electrolysis to explore the costs and benefits of flexible electrolysis operation considering variable wholesale electricity prices. With strategic operating schedules, cost reductions, and efficiency improvements, electrolysis shows promise as a low-carbon, cross-sector, market competitive, and flexible source of hydrogen.
(24th Conference on Structural Mechanics in Reactor Technology, 2017) Varma, Amit; Kim, Joo Min; Seo, Jungil; Bruhl, Jakob C.
Steel-plate composite (SC) walls are gaining momentum as an innovative system for design and construction of safety-related nuclear facilities due to their modularity and resistance to impactive and impulsive loading. Impactive design focuses on preventing perforation of the wall by the impacting missile. Once perforation has been prevented (through design), other local damage states such as punching shear failure, excessive deflection, and steel faceplate rupture need to be considered. Current approaches use single or two degree-of-freedom (SDOF or TDOF) models along with a static resistance function to estimate the maximum deflection and ductility demand on the wall if missile perforation is prevented. This paper focuses on numerically developing the static resistance function for SC walls, while simultaneously considering the ductility associated with local failure modes such as punching shear failure, flexural yielding followed by shear failure, and plastic mechanism formation. The paper details the development of 3D nonlinear finite element models of SC walls subjected to concentrated loading up to and beyond failure. The models account for various complexities of behavior including steel plate yielding and fracture, tie bar yielding and fracture, concrete cracking and crushing, and stud anchor slip capacity. The paper shows that for a given faceplate reinforcement ratio (4.3%), the local failure mode changes from punching shear failure to flexural yielding (followed by shear failure) to plastic mechanism formation as the tie bar (shear) reinforcement ratio increases (0.18 - 0.85%). The transitions in the local failure modes depend on the plastic strain demands and capacities in the components of the SC wall, namely, the steel plate, tie bar, and stud anchor. The paper identifies the future research path, and how the results can be used to design the preferred hierarchy of local failure modes.
Material Properties of the Grade 300 and Grade 270 Prestressing Strands and their Impact on the Design of Bridges
(Virginia Polytechnic Institute and State University, 2006) Hill, Aaron T.
The primary objective of this thesis was to test the material properties of the new Grade 300, low-relaxation prestressing strand. The purpose of this testing was to verify the advertised breaking strengths and relaxation properties of the Grade 300 strand. Additional properties, such as yield strength, modulus of elasticity, and elongation, were also examined. Several tests were performed on each specific type of strand. For example, six tension and eight relaxation tests were performed on the Grade 300, 0.5 in. diameter, 0.153 square in. area strand. From the tests, it is concluded that the advertised breaking strengths and relaxation properties from Strand-Tech Martin, Inc. were accurate and meet the industry standards for low relaxation strand. The secondary objective of this project was to comment on the benefits of the Grade 300 strand as it pertains to the bridge industry. It was concluded from the tests that the Grade 300 strand had a 10 per cent larger 1 per cent elongation stress compared to the bridge industry standard Grade 270 strand. Furthermore, the amount of loss due to relaxation for the Grade 300 strand was comparative to that of the Grade 270 strand. While additional testing needs to be done to include stress-corrosion, transfer length, development length, and flexural strength, the completed testing indicates that less strand will be required using Grade 300 strand versus Grade 270 strand to achieve a set span length and transverse girder spacing. In addition, with the industry gradually progressing toward using higher strength concretes, longer span lengths and larger transverse girder spacing can be achieved by using the Grade 300 higher strength strand. The final objective of this testing was to examine the procedures and testing methods outlined by ASTM A416, Standard Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete (2005), ASTM E328, Standard Test Methods for Stress Relaxation for Materials and Structures (2002), and ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products (2005). The breaking strength and yield strength tables in ASTM A416 (2005) need to be updated with the new Grade 300 strand information. Based on this testing, ASTM should also remove the recommendation of simply using aluminum foil and Standard V-Grips to grip the strand. Even though the standard Grade 270 and Grade 300 regular diameter strand met the material property requirements when using aluminum foil as a cushioning material, none of these samples broke clearly within the gage length of the strand. Furthermore, all of the super area strand samples failed prematurely at the grips due to the notching effect of the V-grip teeth. Thus, an alternative method involving aluminum tubing, aluminum oxide, and epoxy were used to create a cushioning device between the V-grip and the strand in order to achieve the true ultimate breaking stress of the strand. Finally, ASTM should comment on the impact of test length on the total relaxation measurements. Three test lengths were evaluated during the 26 relaxation tests. As the test length increased, the total measured relaxation decreased. Losses due to chuck slip and frame settlement were negligible as the strand test length increased.