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Title: True load-deformation relationships for coated and uncoated fabrics
Authors: Soils and Pavements Laboratory (U.S.)
United States. Assistant Secretary of the Army (R & D)
Vollor, Timothy W.
Keywords: Fabrics
Coated fabrics
Noncoated fabrics
Publisher: Geotechnical Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: A baseline survey was prepared on the application of fabrics in civil engineering with an emphasis on the testing techniques by which physical and mechanical properties of fabrics and/or membranes are determined. It was found that several characteristics are required to fully evaluate a fabric's potential for use in civil engineering construction. Standard test methods used with fabrics are not always adequate for this evaluation, and new tests are being developed to evaluate fabrics under various specific conditions. These tests should be simple to perform, provide useful information, and be accepted as reasonable by both manufacturer and user. Both new test methods developed by other researchers and test methods presently being used for evaluating fabrics and/or membranes are discussed. Several selected load versus elongation test methods were evaluated in the laboratory. For this evaluation, 10 fabric materials were selected. An attempt was made to select fabrics with a range of physical properties that would enable a better evaluation of the test methods. The Capstan linear variable differential transformer (LVDT) test, a unidirectional test method designed to accurately describe the load versus elongation relationships of both low and high-strength fabrics and/or membranes, was devised. The results of the evaluation indicated that the Capstan test gives representative load versus elongation data for woven fabrics. The effects of slippage in the jaws on the elongation results were eliminated. This method.could also be useful for obtaining load versus elongation properties of high-strength fabrics that cannot be tested by established test methods. When the nonwoven fabrics were tested using the Capstan method, distortion of the fabric caused a skewing of the clasps. This skewing resulted in a binding of the LVDT's, causing incorrect results. Major adjustments in equipment and procedure will be needed to eliminate the distortion problem. The 2-in. cut strip, an established unidirectional test method, was another method evaluated in the laboratory. It was found to be a useful test for woven fabrics with a breaking strength of less than 1000 lb per in. and where the true elongation of the fabric is not critical. The plane strain tensile testing device developed by Sissons at the University of Strathclyde, England, was also evaluated in the laboratory. This method allows restraint of the specimen at right angles to the direction of stressing. The plane strain test method is a workable multidirectional test method, but modification is necessary to restrict or eliminate the effects of the restraining device on the breaking strength of the material. The effect of the restraining device on the breaking strength is not as great with small loads as it is with large loads, and is less with nonwoven fabrics than it is with woven fabrics. Further study of the evaluation of geotechnical fabrics and/or membranes is needed.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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