II= − ∆ X∆ = − ∆ z∆where:
GI, GII, and GIII = mode I, II, and III energy-release rate, respectively
∆u, ∆v, and ∆w= relative displacement between the top and bottom nodes of the crack face
in local coordinates x, y, and z, respectively
Rx, Ry, and Rz = reaction forces at the crack-tip node
∆A = crack-extension area, as shown in the following figure:Figure 11.10: 3-D Crack Geometry Schematic
11.3.2.1.3. Element Support, Mesh and Material Behavior
The VCCT method for energy-release rat e calculation (accessed via the CINT command) supports the
following elements:
- PLANE182
- PLANE183
- SOLID185
- SOLID186
In most cases, ANSYS, Inc. recommends using linear elements including PLANE182 and SOLID185.
The accuracy of the VCCT calculation depends on the meshes. T o ensure the greatest accuracy, use
equal element sizes ahead of and behind the crack-tip node. The mesh size affects the solution; therefore,
it is helpful to examine mesh-size convergence prior to attempting the finite element solution.
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationFracture Mechanics