Investigation of mode-II delamination fracture energy with a discontinuous computational homogenization model

Numerical methods for delamination analysis, such as the cohesive zone method, require fracture energy as an essential input. Existing formulations rely on a phenomenological relationship that links fracture energy to the mode of fracture based on linear elastic fracture mechanics (LEFM). However, doubts exist about the applicability of LEFM....

Experimental characterisation of flexural bond behaviour in brick masonry

The brick-to-mortar bond often represents the weakest link leading to cracking and failure of masonry structures. For this reason, the in-situ characterization of masonry’s flexural bond behaviour (here defined as flexural bond strength and flexural bond fracture energy), is essential for the assessment of existing buildings. Among masonry...

Characterizing and modelling the perpendicular to the grain mode-I fracture process of (tropical) hardwood

The demand to build with wood and other bio-based materials has increased rapidly the last decade, due to the ambition to build more with sustainable building materials. One of the major challenges in building with wood, is to account for the lower strength and stiffness perpendicular to the grain. Wood is an anisotropic material, meaning the...

Experimental and numerical modelling of mode I fracture in tropical hardwoods

The goal of the thesis is to investigate two main questions for the purpose of modelling fractures in timber with a finite element method. The first question is to evaluate the use of digital image correlation during a three point bending test to obtain mean values for tensile strength and fracture energy, and the follow up question is if it is...

Characterization of mode-II delamination fracture energy via computational homogenization

Due to the complex underlying microscopic damage processes, the failure behavior of composite materials is challenging to understand and predict. Fracture mechanics approaches [1] and cohesive zone models [2] that simulate delamination generally consider the fracture energy as a material characteristic that exclusively depends on the fracture...

Effect of cyclic aging on mode I fracture energy of dissimilar metal/composite DCB adhesive joints

In some industrial applications, adhesive joints are cyclically exposed to a moist environment, where cyclic moisture absorption and desorption can significantly alter the fracture energy of the bonded joints. Most previous studies are based on monotonic aging conditions, while the performance of bonded joints under cyclic aging is not well...

Non-linear buckling analysis of GFRP plates: A numerical approach with progressive failure analysis

Fiber Reinforced Polymer (FRP) has increased rapidly in popularity in the past few decades. The material's advantageous properties, such as a high strength-to-weight ratio and low required maintenance, gave rise to its popularity in multiple major engineering branches. Buckling behaviour develops due to the notably low stiffness-to-strength...

A study on fracture toughness of ultra-high toughness geopolymer composites based on double-K criterion

Ultra-high toughness geopolymer composites (UHTGC) were fabricated based on the matrix of binder composed of alkali-activated fly-ash and granulated blast furnace slag and polyvinyl alcohol (PVA) fibres in this research. The tensile behaviour and fracture toughness of UHTGC are investigated on both macro and microscales experimentally and...

Modeling of dynamic mode I crack growth in glass fiber-reinforced polymer composites: fracture energy and failure mechanism

The mode-I dynamic fracture energy and failure mechanisms of glass fiber-reinforced polymer composites are investigated with an embedded cell model of the single-edge-notched-tension (SENT) geometry. Under an applied dynamic loading, a crack may propagate in the embedded microstructure, accompanied by the development of a fracture process...

Material Characterization Approach for Modeling High-Strength Concrete after Cooling from Elevated Temperatures

Advanced numerical modeling of high-strength concrete (fc>60 MPa) structures designed to withstand severe thermal conditions requires detailed and reliable information on the mechanical properties of the material exposed to elevated temperatures. The only uniaxial compressive strength variation with temperature is not enough to satisfy the...

Estimation of Energy Released from Crack in Concrete using Acoustic Emission and Comparison with the Numerical Results

Study relating Acoustic Emission (AE) energy to fracture energy has been conducted in the past and a correlation has been reported between the two. The scope of these studies has remained limited to laboratory size specimens with known crack location and the energy release being investigated on a global scale. The objective of this research is...

Determination of fracture energy of early age concrete through a uniaxial tensile test on an un-notched specimen

Unlike the notched specimens for conventional concrete fracture tests, this paper introduces a deformation-controlled uniaxial tensile test on an un-notched specimen. The surface of the dog bone-shaped specimen is a second order parabolic curve, and the gradual change in the specimen shape does not lead to extreme stress concentrations....

Fracture behavior in a modified Transverse Crack Tension test under compressive stress: A qualitative study on model parameters

An increase in apparent mode II fracture toughness in Fiber Reinforced Polymers has been found from modified Transverse Crack Tension (mTCT) tests with compressive stresses added orthogonal to the delamination plane. Numerical reproduction of these results has not yet led to a good understanding of the reasons for this behavior. Currently, an...

Determination of fracture strength and fracture energy of (metallo-) ceramics by a wedge loading methodology and corresponding cohesive zone-based finite element analysis

A wedge loaded testing methodology to determine the fracture energy and strength of (semi-) brittle (metallo-)ceramics is presented. The methodology combines a tailored specimen geometry and a comprehensive finite element analysis based on cohesive zone modelling. The use of a simulation-based approach to extract both fracture strength and...

A mesoscale modelling perspective of cracking process and fracture energy under high strain rate in tension

This paper presents a numerical modelling study on the simulation of the cracking process and fracture energy in concrete under high strain rate. To capture the stress wave effect and the damage evolution at the meso-length scale, both a homogeneous model with a millimetreresolution mesh and an explicit heterogeneous mesoscale model with random...

A plane stress softening plasticity model for orthotropic materials

Failure in plain and reinforced concrete - An analysis of crack width and crack spacing

Fracture mechanics of concrete: Will applications start to emerge?

Fracture mechanics of concrete has developed into an active field of research in the past decades. It promises a rational solution technique to structural problems in reinforced concrete in the limit state. Numerical tools have been developed on the basis of fracture mechanics theories. The question to be addressed is how much of the early...