Laboratorial test monitoring applying photogrammetric post-processing procedures to surface displacements

Abstract Most of the traditional laboratorial methods for monitoring displacements and strains at the surface of the specimen present several constraints, namely: (i) limitations in hardware positioning; (ii) costly equipment and human resources; and (iii) time-consuming data processing. Consequently, the development of new methods capable of eliminating these drawbacks is of utmost interest. Herein, a new technique for laboratorial test monitoring is presented. By using photogrammetry and image post-processing, all the above mentioned drawbacks are overcome. Furthermore: (i) both displacement and strain fields can be monitored at a practically unlimited number of target points at any stage; (ii) it is a cost effective method, since data is acquired with non-professional digital cameras; and (iii) it is a fast procedure since data is automatically processed. Additionally, high precision is reached allowing an accurate characterisation of the fracture localisation process, including the establishment of a correlation between the latter and the localisation of cracks and their evolution in time.