Mechanical APDL Structural Analysis Guide

J-Integral or stress-intensity evaluation supports the following material behavior:

• Linear isotropic elasticity


• Isotropic Plasticity

11.3.1.2. J-Integral Calculation

The program calculates the J-Integral at the solution phase of the analysis after a substep has converged,
then stores the value to the results file.

The CINT command initiates the J-Integral calculation and also specifies the parameters necessary for
the calculation.

Perform the J-Integral calculation as follows:

11.3.1.2.1. Step 1: Initiate a New J-Integral Calculation

11.3.1.2.2. Step 2: Define Crack Information

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

11.3.1.2.4. Step 4: Define a Crack Symmetry Condition

11.3.1.2.5. Step 5: Specify Output Controls

11.3.1.2.1. Step 1: Initiate a New J-Integral Calculation

To start a J-Integral calculation, use the CINT command's NEW option and provide a number to identify
the input information for the J-Integral calculation. The command syntax is:

CINT,NEW,n

where n is the number identifying this J-Integral calculation.

For example:

CINT,NEW,1! initiate a new J-Integral calculation as # 1

11.3.1.2.2. Step 2: Define Crack Information

The crack-tip node component and the crack-extension direction are both necessary for a J-Integral
calculation. Two methods using the CINT command are available for specifying the values:

tion 11.3.5.2.2.2. Define the Crack-Extension Node Component and Crack-Extension Direc-

This approach applies for both 2-D crack geometry and 3-D flat crack surfaces. It offers a simple way

to define a 3-D J-Integral calculation, as you need only define the crack-tip (front) node component

and the normal of the crack plane. Use this method when the crack plane is flat.

• Define the crack-extension node component and crack-extension direction.

This approach applies for 3-D curve crack planes, where a unique normal may not exist. However,

you must define the crack-extension node component and the crack-extension direction at each

crack-tip node location. Use this method when the crack plane is not flat, or when a set of nodes

form the crack tip, as in the case of a collapsed crack-tip mesh.

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Numerical Evaluation of Fracture Mechanics Parameters