Mechanical APDL Structural Analysis Guide

CINT,SYMM,ON

Example:

CINT,NEW,1

CINT,TYPE,VCCT

CINT,SYMM,ON! crack 1 is a symmetrical crack

11.3.2.2.4. Step 4: Specify Output Controls

Similar to the J-Integral calculation, the program calculates the energy-release rat e during the solution
phase of the analysis and stores the results in the .rst file for postprocessing.

Energy-release rat e output uses all of the defaults from the OUTRES command. The OUTRES,ALL
command includes CINT command results. However, you can issue an OUTRES,CINT command to
control the specific output for energy-release rat e results only.

Example:

CINT,NEW,1

CINT,TYPE,VCCT

CINT,CTNCP,CRACK_TIP_NODE_CM

CINT,SYMM,ON

OUTRES,CINT,10! output CINT results every 10 substeps

11.3.3. Stress-Intensity Factor Calculation

Two approaches for evaluating stress-intensity factors are available:

• Interaction integral method -- ANSYS performs the stress-intensity factors calculation at solution and
  stores the results to the result file for postprocessing.


• Displacement extrapolation method -- ANSYS performs the stress-intensity factors calculation during
  postprocessing.

11.3.3.1. Calculating Stress-Intensity Factors via Interaction Integrals

Similar to the domain integral method for J-Integral evaluation, the interaction integral method for
stress-intensity factors calculation applies area integration for 2-D problems and volume integration for
3-D problems. In comparison to the traditional displacement extrapolation method, the interaction in-
tegral method offers better accuracy, fewer mesh requirements, and ease of use.

The following topics are available:

11.3.3.1.1. Understanding Interaction Integral Formulation

11.3.3.1.2. Calculating the Stress-Intensity Factors

11.3.3.1.1. Understanding Interaction Integral Formulation

The interaction integral is defined as

ij klkl

aux

ij kj

aux

ki kj ki

aux

V n

s

= −∫ ,(σ ε δ −σ ,−σ , ) ∫δ

where:

σ ε
 
 

are the stress, strain and displacement,

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Numerical Evaluation of Fracture Mechanics Parameters