Reliability oriented optimum design of the LHC interconnections - Part I: Mechanical compensation system

This LHC Project Note is aimed at defining and verifying the reliability levels of the LHC mechanical compensation system. The apportionment of the reliability levels to the components (bellows expansion joints) is integrated into the optimum design of the LHC interconnections. The prototype expansion joints constructed following the results of the optimisation procedure were tested at CERN under the cyclic loads representing the real service conditions. As a result of the statistical analysis, the Weibull probability density function has been identified. Finally, the assumed reliability levels were confirmed with respect to all bellows expansion joints. The test results were used to improve the numerical model that will serve to anticipate the response of expansion joints under the exceptional conditions of service.