DIC for deformation assessment: A case study

The aim of this paper is to present in detail case study, where the deformation of a complex connection system of a modular bridge are measured by means of the digital image correlation (DIC) technique, in order to study the displacements in the joint. The connection system is composed of metallic and composite parts. The paper shows that DIC is a complementary tool of the conventional measurement systems such as LVDT and strain gages. The use of strain gages and LVDT only allows to suggest where the major part of the deformation is located, but does not allow to understand the origin of the deformations. The DIC analysis permits to locate and to quantify the different sources of deformation, which may lead to the improvement of the design and the assembly procedure of the connection. The paper also points out the set-up procedure for the use of the CCD camera, and the precautions which must be taken concerning the contrast pattern to place on the specimen, the light conditions, the calibration procedure and the magnification factor, which must be used especially in this case where different planes are measured.