Argon Excluder Foam Compression Data

The argon excluder is designed to reduce the media density of the dead space between the internal modules of the end calorimeters and the concave convex head to less than that of argon. The design of the excluder includes a thin circular stainless steel plate welded to the inner side of the convex pressure vessel head at a radius of 26 and 15/16 inches. It is estimated that this plate will experience a pressure differential of approximately 40 pounds per square inch. A inner foam core is incorporated into the design of the excluder as structural support. This engineering note outlines the compression data for the foam used in the north end calorimeter argon excluder. Four test samples of approximately the same dimensions were cut and machined from large blocks of the poured foam. Two of these test samples were then subjected to varying compression magnitudes until failure. For this test failure was taken to mean plastic yielding or the point at which deformation increases without a corresponding increase in loading. The third sample was subjected to a constant compressive stress for an extended period of time, to identify any 'creeping' effects. Finally, the fourth sample was cooled to cryogenic temperatures in order to determine the coefficient of thermal expansion. The compression test apparatus consisted of a state of the art INSTROM coupled with a PC workstation. The tests were run at a constant strain rate with discrete data taken at 500 millisecond intervals. The sample data is plotted as a stress strain diagram in the results. The first test was run on sample number one at a compression rate of 0.833 mills or equivalently a strain rate of 3.245 x 10{sup -4} mil/mills. The corresponding stress was then calculated from the force measured divided by the given initial area. The test was run for thirty minutes until the mode of failure, plastic yielding, was reached. The second test was run as a check of the first using sample number two, and likewise was conducted in the same manner. However, the strain rate for the second test was increased to 6.66 x 10{sup -4} mil/mills which reduced the test time to fifteen minutes. The third sample was subjected to a compressive stress of forty pounds per sqaure inch, the estimated MAWP, for a period of thirty minutes. Data was taken manually by the operator and an estimate is provided in the results. The thermal test conducted on sample number four consisted of cooling the sample to 77K using an open mouth dewar filled with liquid nitrogen. The sample was then measured (all dimensions) warm, 298K, and cold, 77k, and the measurements compared. The sample was then allowed to warm and the test was repeated. The calculation of the coefficient of thermal expansion is provided in the results