Measurement of Zircaloy-4 cladding tube deformation using a three-dimensional digital image correlation system with internal transient heating and pressurization

Abstract

In this study, multi-dimensional (Multi-D) deformation of a Zircaloy-4 cladding tube under internal transient heating and pressurization conditions was measured by experimental setup named ‘Experimental setup to investigate high temperature deformation of cladding tube under internal pressurizing and heating (EIGEN)’ and three-dimensional digital image correlation (3D DIC) system. The ‘EIGEN’ experimental setup was designed to investigate high temperature deformation of the cladding tube under inert gas atmosphere. The 3D DIC system based on stereovision was further developed to be applied to high temperature by using high temperature resistant speckle pattern and bandpass filter. To evaluate measurement accuracy of the 3D DIC system, validation works of 3D DIC calibration were performed with proposed methodology. Additionally, a 3D finite element model (FEM) of the ‘EIGEN’ experiment was developed to evaluate the results of the 3D DIC. Finally, ‘EIGEN’ experiment was conducted under several fill pressure conditions such as 30, 50, 60, 70 bars. As a result, the established 3D DIC system could successfully measure in-situ and real-time large deformation such as ballooning and rupture as well as full-field multi-D deformation of the cladding tube at the high temperature under the inert atmosphere. Multi-D strains from the 3D DIC showed good agreement with calculated ones of the 3D FEM, and they were also compared with 3D laser scanning results for validation.