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Title: Evaluation of XM18Q extruded aluminum landing mat
Authors: United States. Army Materiel Command.
Smith, Carroll J.
White, D. W. (Dewey W.)
Keywords: Aluminum landing mats
Cable roll-over tests
Dow landing mats
Extruded aluminum
Landing mats
Skid tests
Traffic tests
XM18Q landing mat
Publisher: Soils and Pavements Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: The investigation reported herein was conducted to evaluate an extruded aluminum alloy landing mat (designated XM18Q) supplied by the Dow Chemical Company, Madison, Ill. The mat, which was fabricated by the Washington Aluminum Company (WACO), Enterprise, Ala. (Dow's subcontractor), is a one-piece extrusion fabricated from 6061 aluminum alloy artificially aged to the T6 condition. The mat panels are interlocked along the sides by means of a hinge-type connector, the components of which are an integral part of the basic panel extrusion. End connectors, composed of extruded connectors welded to the basic panel, consist of overlap and underlap sections secured by a locking bar after individual panels have been joined together. The mat mentioned herein was different from modified MX18-B mat in that the insert tubes in the ends of the mat panels were shortened by ¾ in. and the amount of metal was increased in the area of the female connector and first cavity adjacent to this connector. The method of attaching the end connectors to the mat extrusion was changed to allow improved welds at the corners. The investigation consisted of traffic, skid, cable roll-over, and laboratory tests to obtain information for use in evaluating the XM18Q mat for potential use as a medium-duty landing mat. The test data reported herein were evaluated against the criteria for medium-duty mat as established in the revised Qualitative Materiel Requirement (QMR). Traffic tests were conducted with the mat placed on a prepared subgrade and trafficked with a rolling wheel load simulating actual aircraft operations. The. XM18Q mat, which weighs 4.8 lbs per square foot of placing area, was assembled at an average rate of 600 sq ft per man-hour. The mat's weight exceeds the maximum QMR requirement for a medium-duty mat of 4.5 lb per square foot of placing area, and the placing rate exceeds the minimum QMR requirement of 250 sq ft per man-hour. The traffic tests were conducted using the F-4C loading, which consists of a single-wheel load of 25,000 lb with a tire inflation pressure of 250 psi, on a mat-surfaced subgrade with a rated CBR of 4.1. Results of this investigation revealed that the XM18Q mat sustained 940 actual coverages of traffic on a subgrade with a rated CBR of 4.1, which is equivalent to 850 coverages on a 4-CBR subgrade. This falls short of the QMR 1000-coverage requirement for a medium-duty mat on a 4-CBR subgrade. The average coefficients of friction obtained from skid tests on wet and dry surfaces were 0.45 and 0.52, respectively. These coefficients of friction fall within the QMR range of 0.4 to 0.8. The tire wear resulting from skidding on both the wet and dry surfaces was not considered significant. Cable roll-over tests were conducted on the XM18Q mat with a 1-in.-diam arresting cable trafficked with a 25,000-lb single-wheel load with a tire inflated to 250 psi, Results indicated that the mat will withstand the 20 cable roll-overs stipulated in the QMR. Laboratory tests conducted on the mat indicated that the 6061 T-6 alloy exceeded the minimum physical requirements.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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