Project Outline

Overview

The CreepImage project will develop a digital image technique for long term measurement and monitoring of creep deformation of an engineering structure/component under harsh conditions (high temperature, irradiation etc.) where direct sensor attachment and human access are difficult or dangerous. A high definition digital camera equipped with a suitable lens (macro, telescopic or telecentric lens) will be used to capture images of a grid on the component surface at various stages, and digital image correlation (DIC) will be used to calculate the deformation associated with creep behaviour of the component.

The procedure is expected to be as follows: (1) Physically produce a grid on the surface of the structure. It serves as the information carrier from which deformation can be calculated by DIC. (2) Capture digital images of the grid at different stages. A reference plate with a stable known coefficient of thermal expansion (CTE) will be placed adjacent to the grid such that it can be imaged simultaneously. This permits automatic calibration without the need to keep the camera on site all the time. (3) DIC software will be used to calculate the overall deformation. Creep strain is obtained by subtracting the thermal deformation.

The project work will be a laboratory based demonstration to validate the proposed techniques and to investigate the measurement capability (accuracy, repeatability etc.). In addition to nuclear plants, other potential application areas include evaporators in a power plant.