LOADING ADJUSTMENT POLICY OF A 2-UNIT SHARED-LOAD SYSTEM BASED ON RELIABILITY MANAGEMENT

The expected life of a shared-load system can be extended if the adjus tment of loads is allowed. In this paper, this goal is achieved by kee ping the system's reliability always in the maximum situation during i ts service. A design example of a two-column supporting system is used to demonstrate this idea. Two kinds of materials, 316-SS and Cr-Mo, a re considered. The thermal environments of the columns are different, one is 568 degrees C and the other 501 degrees C. Material creep pheno menon dominates the strength decay which follows the Manson-Haferd mod el. The results show that the expected life of the optimal load-adjust ing case is approximately four times that of the averaging-load case. The numerical example also investigates the variations of one-nit surv ival probabilities and it shows that the columns fail almost at the sa me time for different loading situations, but it is still at a very lo w level when the optimal-load adjustment is made. This indicates that the optimal loading situation gets inside the spirit of the design pri nciple, even at the operation time beyond the system's expected life. (C) 1998 Elsevier Science Limited.