A Study of Crack–inclusion Interactions and Matrix–inclusion Debonding Using Moiré Interferometry and Finite Element Method

Abstract

Failure behavior of composite materials in general and particulate composites in particular is intimately linked to interactions between a matrix crack and a second phase inclusion. In this work, surface deformations are optically mapped in the vicinity of a crack-inclusion pair using moiré interferometry. Edge cracked epoxy beams, each with a symmetrically positioned cylindrical glass inclusion ahead of the tip, are used to simulate a compliant matrix crack interacting with a stiff inclusion. Processes involving microelectronic fabrication techniques are developed for creating linear gratings in the crack-inclusion vicinity. The debond evolution between the inclusionmatrix pair is successfully mapped by recording crack opening displacements under quasi-static loading conditions. The surface deformations are analyzed to study evolution of strain fields due to crack-inclusion interactions. A numerical model based on experimental observations is also developed to simulate debonding of the inclusion from the matrix. An element stiffness deactivation method in conjunction with critical radial stress criterion is successfully demonstrated using finite element method. The proposed methodology is shown to capture the experimentally observed debonding process well.

Recent Applications of Moiré Interferometry

“…It is recognized as permanent deformation in the neighborhood of the crack path, and for nonmetals it is known as the damage wake. Moiré interferometry has been used extensively for experimental fracture mechanics, most notably, crack tip displacement measurement [120][121][122][123][124][125] and deformation analyses of fracture zone near a crack tip [126][127][128][129][130][131][132][133][134].…”

“…Kang and Lu [122] investigated the displacement fields near the tip of a crack in a bimaterial joint under mixed-mode loading. Savalia and Tippur [125] mapped the debonding evolution between the inclusion-matrix pair in a composite by recording crack opening displacements using moiré interferometry. The representative surface deformations analyzed in the study are shown in Fig.…”

Study on the effect of inclusion shape on crack-inclusion interaction using digital gradient sensing method

“…Savalia and Tippur [12,18] conducted a study of crackinclusion interactions and matrix-inclusion debonding using Moiré interferometry. Jajam and Tippur [19,20] carried out an experimental investigation of dynamic crack growth past a stiff inclusion using digital image correlation (DIC).…”

The Influence of Coating Fabrication Processes on the Optical Efficiency of Replicated Moiré Diffraction Gratings

“…In the last decades, the optical experimental technique, Moiré Interferometry, has been implemented in many fields, of which the most important are the material characterization [2][3][4], microelectronics devices [5,6], micromechanics [7,8], fracture mechanics [9][10][11], the residual stress [12][13][14], composite materials [15,16] and biomechanics [17,18]. For all these cases the main goal is the global measurement of displacement fields without contact with high resolution and accuracy that the Moiré Interferometry method can offer.…”