Experimental study on fracture behavior of pre-notched mortar beams using ESPI technique

Abstract

Electronic Speckle Pattern Interferometry (ESPI) technique is of high sensitivity and can provide full-field surface deformation. This paper introduces the application of ESPI technique to measure the surface deformation of pre-notched mortar beams in three-point bending tests. In addition to ESPI, Linear Variable Differential Transformers (LVDTs) and clip gauge extensometer were used to measure the mid-span deflection and Crack Mouth Opening Displacement (CMOD) of the beam respectively. Displacements measured by ESPI are compared with that obtained from LVDTs and clip gauge to verify the accuracy of ESPI. From the displacement field measured by ESPI, one of the nonlinear fracture properties of quasi-brittle materials, Crack Tip Opening Displacement (CTOD) was determined and load-CTOD curve is plotted. Furthermore, crack propagation process and Crack Opening Displacement (COD) profiles at different loading stages are presented. Some fracture parameters of the mortar specimen are quantified.