COALESCENCE MODEL OF TWO COLLINEAR CRACKS EXISTING INSTEAM GENERATOR TUBES

摘要

The 40 % of wall thickness criterion has been used as a plugging rule of steam generator tubes but it can beapplicable just to a single-cracked tubes. In the previous studies preformed by the authors, a total of 10 local failureprediction models were introduced to estimate the coalescence load of two adjacent collinear through-wall cracksexisting in thin plates, and the reaction force model and plastic zone contact model were selected as optimummodels among them. The objective of this study is to verify the applicability of the proposed optimum local failureprediction models to the tubes with two collinear through-wall cracks. For this, a series of plastic collapse tests andfinite element analyses were carried out using the tubes containing two collinear through-wall cracks. It has beenshown that the proposed optimum failure models can predict the local failure behavior of two collinearthrough-wall cracks existing in tubes well. And a coalescence evaluation diagram was developed which can beused to determine whether the adjacent cracks detected by NED coalsece or not.