Inverse method for temperature and stress monitoring in complex-shaped bodies

Abstract

The purpose of this work is to formulate a space marching method, which can be used to solve inverse multidimensional heat conduction problems. The method is designed to reconstruct the transient temperature distribution in a whole construction element based on measured temperatures taken at selected points on the outer surface of the construction element. Next, the Finite Element Method is used to calculate thermal stresses and stresses caused by other loads such as, for instance, internal pressure. The developed method for solving temperature and total stress distribution is tested using the measured temperatures generated from a direct solution. Transient temperature and total stress distributions obtained from the method presented below are compared with the values obtained from the direct solution. Finally, the presented method is experimentally verified during the cooling of a thick-walled cylindrical element. The model of a pressure vessel was preheated at 300 °C and then cooled by cold water injection. The comparison of results obtained from the inverse method with experimental data shows the high accuracy of the developed method. The presented method allows to optimize the power block’s start-up and shut-down operations, contributes to the reduction of heat loss during these operations and to the extension of power block’s life. The fatigue and creep usage factor can be computed in an on-line mode. The presented method herein can be applied to monitoring systems that work in conventional as well as in nuclear power plants.