## What is cohesive crack?

Cohesive crack models are used when the mechanical damage is confined within a narrow band along the crack line, and the behavior in this band is strain softening and produced by microcracking in the matrix and by aggregate interlocking.

## What is Dugdale model?

The purpose of the Dugdale model was to develop a relationship between. plastic zone size, applied load, and crack length. It was originally developed. for the case of a crack in an infinite plate subjected to remote tension, under. plane stress conditions in an elastic-perfectly-plastic material.

**What is a cohesive element?**

The cohesive element connects two surfaces together, with the separation governed by a traction-separation law.

**What is traction separation?**

12.3. The traction–separation relationship is such that with increasing opening displacement the traction across the interface reaches a maximum, σmax, then decreases and eventually vanishes, permitting a complete separation at an opening displacement of δf, as shown in Figure 12.9.

### What is the main limitation of Griffith’s theory?

Engineering materials are so tough that pure Griffith theory cannot describe them. The length of the crack is important: the higher the length, the lower the strength (for Griffith geometry). Other crack geometries give different results from Griffith, e.g., high length, same strength for a delamination crack.

### How to define a crack in XFEM?

If an initial crack is wanted, it is very easy to define with XFEM. A separate part representing the crack (without properties or mesh) can be instanced into the assembly and moved to the correct position. By choosing this part as crack location, the crack is defined. The crack does not need to be along the element edges.

**What does XFEM stand for?**

The methodology simulates microcrack initiation and propagation using the extended finite element method (XFEM) and delamination using a mixed-mode cohesive zone model. Random microcrack initiation is modelled using a random (Weibull) distribution of fracture strengths.

**Can XFEM be used for J-integrals?**

XFEM can also be used for stationary cracks, allowing contour integrals such as the J-integral to be calculated with less meshing effort. This is not discussed here. In this example, no initial crack is defined: it will develop based on the damage initiation criterion. If an initial crack is wanted, it is very easy to define with XFEM.

## Is there an XFEM with an explicit crack description for hydraulic fracture?

The XFEM with an explicit-implicit crack description for hydraulic fracture problems Eff Sustain Hydraul Fract(2013), 10.5772/56383 Chapter 35 Google Scholar