Macro- and micro-modeling of crack propagation in encapsulation-based self-healing materials: Application of XFEM and cohesive surface techniques

Abstract

A B S T R A C TEncapsulation-based materials are produced introducing some small healing fluid-filled capsules in a matrix. These materials can self-heal when internal cracks intercept and break the capsules. If the healing agent is released, the crack can be sealed. However, this is not always the case. These capsules need to be designed with the adequate shape and material to be properly broken. This paper presents two application models based on the combination of eXtended Finite Element Method (XFEM) elements and Cohesive Surfaces technique (CS) to predict crack propagation. Two types of encapsulated systems are considered: a concrete beam in a three-point bending test, and a micro-scale model of a representative volume element of a polymer subjected to a uniaxial tensile test. Despite both systems relying on different capsule shapes and different constituent materials, the models predict a similar non-linear response of the overall material strength governed by the coupled effect of the interface strength and the capsule radii-to-thickness ratio. Furthermore, even if an inadequate material and geometry combination is used, it is found that the mere presence of capsules might achieve, under certain conditions, an interesting overall reinforcement effect. This effect is discussed in terms of clustering and volume fraction of capsules.

Research Progress on Numerical Models for Self‐Healing Cementitious Materials

“…Gilabert et al developed a finite element model that used a combination of extended finite element method (XFEM) and the cohesive surfaces (CS) technique to simulate the mechanical behavior of self‐healing material systems with encapsulated healing agents. Two scenarios were explored: one was a microscale model that comprised a microcapsule embedded in a cementitious matrix and the other was a macroscale model that considered the effect of adding tubular glass capsules on the overall bending response of a cementitious beam.…”

A review study on encapsulation‐based self‐healing for cementitious materials

“…Gilabert et al combined eXtended Finite Element Method (XFEM) elements and cohesive surface (CS) techniqus to predict crack propagation and brekage of the capsules. They simulated the response of a beam with encapsulated systems in a three‐point bending test, concluding that when using capsules with t/R less than 0.12, a minimum interface strength of 2.0 MPa has to be ensured to break the capsuels and liberate the healing agent.…”

A micromechanical fracture analysis to investigate the effect of healing particles on the overall mechanical response of a self‐healing particulate composite

“…() For instance, efforts are taken to estimate the effective elastic properties of self‐healing particulate composites, whereby the effect of dispersed healing particles on the elastic moduli of the host matrix material is quantified. () Crack propagation studies were conducted in an idealised healing capsule(s)‐matrix system, and the effects of geometric and material parameters were analysed using cohesive zone model and extended finite element method (XFEM) . In particular, a self‐healing concrete in a three‐point bending test set‐up was utilised to evaluate the influence of parameters such as number, size, and position of capsules on the mechanical behaviour of the concrete.…”

“…In the context of self-healing particulate composite systems, a limited number of modelling studies have been conducted in terms of quantifying the effective mechanical properties and crack path predictions. [28][29][30][31][32][33] For instance, efforts are taken to estimate the effective elastic properties of self-healing particulate composites, whereby the effect of dispersed healing particles on the elastic moduli of the host matrix material is quantified. 30,31 Crack propagation studies were conducted in an idealised healing capsule(s)-matrix system, and the effects of geometric and material parameters were analysed using cohesive zone model and extended finite element method (XFEM).…”

“…30,31 Crack propagation studies were conducted in an idealised healing capsule(s)-matrix system, and the effects of geometric and material parameters were analysed using cohesive zone model and extended finite element method (XFEM). 28 In particular, a self-healing concrete in a three-point bending test set-up was utilised to evaluate the influence of parameters such as number, size, and position of capsules on the mechanical behaviour of the concrete. This was then followed by modelling an idealised single healing capsule-matrix volume element, whereby the influence of interface properties and capsule volume fraction on the effective strength was reported.…”