An adaptive floating node based formulation for the analysis of multiple delaminations under quasi-static loading

A novel and efficient numerical formulation for the modelling of multiple delaminations growth in laminated composite materials subjected to quasi-static loading is presented. The proposed formulation alleviates the high computational cost associated with models featuring cohesive elements by using a novel Adaptive Refinement Scheme and an...

Computational analysis of fracture and healing in thermal barrier coatings

Thermal Barrier Coating (TBC) systems are protective layers applied to critical structural components of gas turbines operating at high-temperature. A typical TBC system consists of three different layers, namely a ceramic Top Coat (TC), an active Thermally Grown Oxide (TGO) layer and a metallic Bond Coat (BC). The outer ceramic TC that protects...

Higher order adaptively integrated cohesive element

Cohesive Element (CE) is a well-established finite element for fracture, widely used for the modelling of delamination in composites. However, the computational time of CE-based method is prohibitive. This is because the steep and non-smooth stress gradient in the cohesive zone requires a very fine mesh. In this context, a new type of CE is...

Overcoming the cohesive zone limit in composites delamination: modeling with slender structural elements and higher-order adaptive integration

Cohesive element (CE) is a well-established finite element for fracture, widely used for the modeling of delamination in composites. However, an extremely fine mesh is usually needed to resolve the cohesive zone, making CE-based delamination analysis computationally prohibitive for applications beyond the scale of lab coupons. In this work, a...

Multiscale modeling of the effect of sub-ply voids on the failure of composite materials

A multiscale fracture model is developed to study the influence of defects appearing at a microscale in a fiber-reinforced composite laminate. The model establishes a link between the geometrical characteristics of sub-ply imperfections that may be created during manufacturing and the overall fracture strength and fracture energy of the...

Numerical Investigation into the Effect of Splats and Pores on the Thermal Fracture of Air Plasma-Sprayed Thermal Barrier Coatings

The effect of splat interfaces on the fracture behavior of air plasma-sprayed thermal barrier coatings (APS-TBC) is analyzed using finite element modeling involving cohesive elements. A multiscale approach is adopted in which the explicitly resolved top coat microstructural features are embedded in a larger domain. Within the computational...

On cohesive element parameters and delamination modelling

The cohesive element (CE) has been widely used to model delamination in laminated composites. The penalty stiffness, interfacial strength and fracture toughness are three CE parameters that often determine the accuracy of the numerical analysis by finite elements (FEs). The fracture toughness may be experimentally determined through standard...

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

A computational fracture analysis is conducted on a self-healing particulate composite employing a finite element model of an actual microstructure. The key objective is to quantify the effects of the actual morphology and the fracture properties of the healing particles on the overall mechanical behaviour of the (MoSi2) particle-dispersed...

Computational investigation of porosity effects on fracture behavior of thermal barrier coatings

The influence of microstructural pore defects on fracture behaviour of Thermal Barrier Coatings (TBC) is analysed using finite element analysis involving cohesive elements. A concurrent multiscale approach is utilised whereby the microstructural features of the TBC are explicitly resolved within a unit cell embedded in a larger domain. Within...

Modelling the fracture behaviour of thermal barrier coatings containing healing particles

The performance of a self-healing Thermal Barrier Coating (TBC) containing dispersed healing particles depends crucially on the mismatch in thermomechanical properties between the healing particles and the TBC matrix. The present work systematically investigates this phenomenon based on numerical simulations using cohesive element-based finite...

Multiscale analysis of mixed-mode fracture and effective traction-separation relations for composite materials

A multiscale framework for the analysis of fracture is developed in order to determine the effective (homogenized) strength and fracture energy of a composite material based on the constituent's material properties and microstructural arrangement. The method is able to deal with general (mixed-mode) applied strains without a priori knowledge...

High Order Adaptively Integrated Cohesive Elements: Development, implementation and testing on composite delamination

Composite delamination represents one of the most critical failure mechanisms occurring in composite structures. In case complex structures are being designed, numerical methods need to be employed. One of the methods to numerically simulate delamination in a Finite Element environment is through the employment of the Cohesive Elements, which...

Effect of pre-existing microstructural defects on elastic and fracture properties of composites

The objective of this research is to explore the effect of microstructural defects on the mechanical properties of fiber reinforced composites. In particular, two kinds of defects are considered in the study, namely, matrix pores and interface precracks. Three-dimensional (3-D) finite element analyses are conducted on Representative Volume...

Multiscale Fracture Simulations for Composite Materials

For failure in composite materials the fracture mechanisms at the microscopic scale, such as matrix cracking, fiber cracking, fiber-matrix debonding or combinations thereof determine the growth of crack at the macroscopic scale. The goal is to develop a simple failure criterion in terms of a bilinear Traction-Separation Law (TSL) for...

A cohesive element based model to describe facture and cohesive healing in elastomers

Several polymeric systems with intrinsic Self-Healing (SH) capabilities have been reported in literature. Many of them showed healing upon contact across the crack interface. Different parameters such as contact time, temperature, pressure or chemical activity determine the degree of healing obtained. In this work, a numerical simulation of the...

A cohesive elements based model to describe fracture and cohesive healing in elastomers

Several polymeric systems with intrinsic Self-Healing (SH) capabilities have been reported in literature. Many of them showed healing upon contact across the crack interface. Different parameters such as contact time, temperature, pressure or chemical activity determine the degree of healing obtained. In this work, a numerical simulation of the...