DEVELOPMENT AND VALIDATION OF INVERSE ANALYSIS OF HEAT CONDUCTION AND THERMAL STRESS FOR ELBOW (PART II)

A heat conduction inverse method for piping elbow was developed to estimate the temperature and stress distribution on the inner surface by measuring the outer surface temperature. In the Part I paper, the derivation and verification of the heat conduction inverse method were described. In the Part II paper, the accuracy for the thermal stress calculation was confirmed by assuming several thermal stratification patters and comparing with the reference results from normal FE heat conduction and thermal stress analyses. As a result, in the case of the measured-basis fluid temperature input from a high temperature-pressure test, the inverse method estimated the maximum stress change by 7% conservative comparing the normal FE analyses. For the assumed temperature change pattern the estimation accuracy was conservatively improved by attaching the additional thermocouples on the outer surface adjacent to the thermal stratification phase. The developed method is practically useful because of short calculate time of 1-2 seconds for 500 time data points after providing the transfer functions.