A new failure mechanism in thin film by collaborative fracture and delamination: Interacting duos of cracks. (November 2015)

• Record Type: Journal Article
• Authors: Marthelot, Joël; Bico, José; Melo, Francisco; Roman, Benoît
• Is Part Of: Journal of the mechanics and physics of solids. Volume 84(2015:Nov.)
• Page Start: 214
• Page End: 229
• Publication Date: 2015-11
• Subjects: Delamination -- Fracture -- Patterns -- Energy methods; Mechanics, Applied -- Periodicals; Solids -- Periodicals; Mechanics -- Periodicals; Mécanique appliquée -- Périodiques; Solides -- Périodiques; Mechanics, Applied; Solids; Periodicals; 531.05
• DOI: 10.1016/j.jmps.2015.07.010
• Languages: English
• ISSNs: 0022-5096

Abstract

Abstract: When a thin film moderately adherent to a substrate is subjected to residual stress, the cooperation between fracture and delamination leads to unusual fracture patterns, such as spirals, alleys of crescents and various types of strips, all characterized by a robust characteristic length scale. We focus on the propagation of a duo of cracks: two fractures in the film connected by a delamination front and progressively detaching a strip. We show experimentally that the system selects an equilibrium width on the order of 25 times the thickness of the coating and independent of both fracture and adhesion energies. We investigate numerically the selection of the width and the condition for propagation by considering Griffith's criterion and the principle of local symmetry. In addition, we propose a simplified model based on the criterion of maximum of energy release rate, which provides insights of the physical mechanisms leading to these regular patterns, and predicts the effect of material properties on the selected width of the detaching strip. Abstract : Graphical abstract: Abstract : Highlights: We study experimentally a new mode of failure of thin brittle coating. Collaboration of fracture and delamination leads to patterns of surprising regularity. The crack interaction is investigated numerically via the principle of local symmetry. Simplified model provides insights of the mechanism leading to these regular patterns.