Mechanical APDL Structural Analysis Guide

adjacent to the first contour of elements. The procedure is repeated for all contours. To ensure correct
results, the elements for the contour integration should not reach the outer boundary of the model
(with the exception of the crack surface).

For a 3-D crack problem, the crack-tip node component is comprised of the nodes along the crack front.
It is not necessary for the crack-tip node component to be sorted. The 3-D material force contour uses
a procedure similar to that of the 2-D contour.

11.3.5.1.2. Element Selection and Material Behavior

The following elements support material force evaluation (accessed via the CINT command):

• PLANE182


• PLANE183


• SOLID185


• SOLID186


• SOLID187

Material force evaluation supports the following material behavior:

• Linear isotropic elasticity


• Nonlinear isotropic elasticity


• Isotropic hardening plasticity


• Kinematic hardening plasticity

11.3.5.2. Calculating Material Force

The program calculates the material forces during the solution phase of the analysis after a substep
has converged, then stores the values to the results file.

The CINT command initiates the material force calculation and specifies the necessary parameters.

Following is the general process for applying material force:

11.3.5.2.1. Step 1: Initiate a New Material Force Calculation

11.3.5.2.2. Step 2: Define Crack Information

11.3.5.2.3. Step 3: Specify the Number of Contours to Calculate

11.3.5.2.4. Step 4: Define a Crack Symmetry Condition

11.3.5.2.5. Step 5: Specify Output Controls

11.3.5.2.1. Step 1: Initiate a New Material Force Calculation

To start a material force calculation, issue the CINT command twice, as follows:

CINT,NEW,n

CINT,TYPE,MFOR

where n is the material force calculation ID number.

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Fracture Mechanics