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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Performance Prediction Relationships for AM2 Airfield Matting Developed from Full-scale Accelerated Testing and Laboratory Experimentation

Rushing, Timothy W 12 August 2016 (has links)
The AM2 aluminum airfield matting system is currently deployed by the United States military for the creation of temporary, rapidly constructed airfields. The ability to predict the number of allowable aircraft passes across an AM2 installation is challenging because of the complex design of the joining system and the fatigue behavior of critical stress elements in the joints. Prior to the writing of this dissertation, the prevailing methods used to predict the performance of AM2 were based on the CBR design procedure for flexible pavements using a small number of full-scale test sections over CBRs ranging from 4 to 10% and simulated aircraft that are no longer in service. The primary objectives of this dissertation are to present the results from nine full-scale experiments conducted on sections of AM2 matting installed on unstabilized soil and gravel subgrades with CBRs of 6, 10, 15, 25, and 100%, and to provide improved relationships that can be used to predict subgrade deformation underneath an AM2 mat installation and the associated fatigue damage when subjected to F-15E and C-17 traffic. Additionally, a laboratory fixture and procedure is described that can be used to evaluate an AM2 style joint in fatigue and directly relate its performance to in-situ field CBR conditions without requiring the expense of full-scale testing. These relationships are suitable to be implemented into design and evaluation frameworks currently used for airfield pavements and matting systems. The main body of this dissertation is a compilation of three complementary articles that describe different components of the main objectives and results from the full-scale experiments on AM2 mat surfaced airfields. The subgrade deformation relationships developed for the F-15E aircraft are presented in Chapter 2, the fatigue damage relationships and the development of the laboratory procedure for the F-15E aircraft are presented in Chapter 3, and the subgrade deformation relationships, fatigue relationships, and laboratory experiments for the C-17 are included in Chapter 4. Chapter 5 presents conclusions and recommendations.
2

Full-Scale Instrumented Evaluations of Multiple Airfield Matting Systems on Soft Soil to Characterize Permanent Deformation

García Beltrán, Lyan Ivonne 14 August 2015 (has links)
Airfield matting systems are used for the expedient construction of temporary airfields and rapid expansion of existing airfields to provide maneuvering support for military aircraft. They protect the subgrade by distributing the load exerted by aircraft over a larger area. Six airfield matting systems of varying materials and designs were evaluated through the construction of full-scale test sections to determine their effectiveness at reducing the accumulation of subgrade deformation and decreasing the pressure experienced by the subgrade. The matting systems were tested on a California Bearing Ratio (CBR) of 6 and subjected to simulated F-15E aircraft traffic while monitoring mat breakage, deformation, and subgrade earth pressure. The systems were compared in terms of the rate of subgrade permanent deformation. Based on test results, a simplified expression was developed to predict subgrade deformation on a CBR of 6 as a function of F 15E aircraft passes and airfield mat properties.

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