PSI - Issue 79

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 79 (2026) 379–385

© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers Keywords: fracture criterion; interface cracks; bridged zone; critical stress Abstract The nonlocal two-parameter fracture criterion of interface cracks with bridged zones is used to solve problems of cracks initiation and growth. This fracture criterion consists of the following conditions: 1) a necessary energy condition of the crack tip limit equilibrium based on the equality of the energy release rate and the rate of the energy dissipation by bonds; 2) a su ffi cient condition of the bond limit stretching at the trailing edge of the bridge zone. From these two conditions, the equilibrium size of the bridged zone and the critical external stress are determined. The regimes of the bridged zone and the crack tip equilibrium and growth are considered: a) the crack tip propagation and the bridged zone size increasing without bonds rupture; b) the bridged zone size decreasing without the crack tip propagation; c) the crack tip propagation with simultaneous bonds rupture. 28th International Conference on Fracture and Structural Integrity - 3rd Mediterranean Conference on Fracture and Structural Integrity Application the nonlocal criterion of bridged cracks growth with necessary and su ffi cient conditions Mikhail Perelmuter ∗ Ishlinsky Institute for Problems in Mechanics RAS, Vernadsky avenue 101-1, Moscow, 119526, Russia

1. Introduction

The most criteria which are used to determine fracture of a crack tip or a reentrant corner tip in materials are assumed that interaction of the newly formed surfaces of the crack can be neglected (Cherepanov, 1979; Yosibash, 2004; Hua et al., 2023). In structurally inhomogeneous materials (composites, adhesive joints) the fracture process zone includes not only a small region near the crack tip, but also the region behind the crack tip (bridged zone) which can be formed by fibers in composites or polymer chains connecting the crack faces in polymer-polymer joints or polymer joints with other materials. The bridging traction in these ligaments between crack faces is a function of the crack opening and increases fracture toughness by reducing the stress intensity factor (SIF). It should be noted that the total SIF at the bridged crack tip is not zero, i.e. a singular stress field is assumed at this crack tip and it is the main di ff erence between the crack model with bridged zone and the cohesive crack model.

∗ Corresponding author. Tel.: + 7-495-433-6257; fax: + 7-499-739-9531. E-mail address: perelm@ipmnet.ru

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers 10.1016/j.prostr.2025.12.348