20.1.2 Defining the crack front

The first step in the procedure to configure a contour integral is to define the crack front by selecting entities from the assembly. The crack front is the forward part of the crack. ABAQUS uses the crack front to compute the first contour integral using all of the elements inside the crack front and one layer of elements outside the crack front. You can request output for more than one contour integral, in which case ABAQUS/CAE adds a single layer of elements to the group of elements that were used to calculate the previous contour integral. Figure 20–2 illustrates how ABAQUS/CAE computes successive contour integrals for a two-dimensional model by adding layers of elements.

Figure 20–2 Successive contour integrals are calculated by adding a layer of elements.

If your part is three-dimensional, ABAQUS computes contour integrals at each node along the crack line, as shown in Figure 20–3. For more information, see “Defining the crack front” in “Contour integral evaluation,” Section 7.10.2 of the ABAQUS Analysis User's Manual.

Figure 20–3 ABAQUS computes the contour integral at each node along the crack line.

The entities from which you can select depend on whether the part instance is an ABAQUS native part or an orphan mesh part and on the modeling space of the part.

ABAQUS native part instance

When you are defining the crack front on an ABAQUS/CAE native part, the entities that you can select depend on the modeling space of the part.

Two-dimensional part instance

If you are defining the crack front on a two-dimensional ABAQUS/CAE native part, you can select the following:

A single vertex

Connected edges

Conected faces

Figure 20–4 shows the entities from which you can select when defining a crack front on a two-dimensional native part.

Figure 20–4 Selecting the crack front from a two-dimensional native part.

Three-dimensional part instance

If you are defining the crack front on a three-dimensional ABAQUS/CAE native part, you can select the following:

Connected edges

Connected faces

Connected cells

Figure 20–5 shows the entities from which you can select when defining a crack front on a three-dimensional native part.

Figure 20–5 Selecting the crack front from a three-dimensional native part.

Orphan mesh part instance

When you are defining the crack front on an orphan mesh part, you can select the elements or element edges or faces that define the crack front. Alternatively, you can select the nodes from the corresponding region. When you are defining the crack front on an orphan mesh part, the entities that you can select depend on the modeling space of the part.

Two-dimensional part instance

If you are defining the crack front on a two-dimensional orphan mesh part, you can select the following:

A single node

Connected element edges

Connected elements

Figure 20–6 shows the entities from which you can select when defining a crack front on a two-dimensional orphan mesh part.

Figure 20–6 Selecting the crack front from a two-dimensional orphan mesh part.

Three-dimensional part instance

If you are defining the crack front on a three-dimensional orphan mesh part, you can select the following:

Connected element edges

Connected element faces

Connected elements

Figure 20–7 shows the entities from which you can select when defining a crack front on a three-dimensional orphan mesh part.

Figure 20–7 Selecting the crack front from a three-dimensional orphan mesh part.