Summary for version 7.0

• The maximum allowed model size is increased to 40000 elements and 200000 nodes (from 12000 and 48000 respectively).
• The input file is modified to a keyword-style structure.
• New options are available for defining crack growth data: Paris equation; Walker equation; tabular da/dn vs deltaK as function of R (up to 100 curves, 100 points per curve); user subroutine to define da/dn.
• Definition of threshold and fracture behaviour is implemented:
• Threshold:
• single threshold value independent of R
• threshold as a function of R using the Walker equation
• threshold as a general function of R
• Harter-T method
• user subroutine option
• Fracture:
• plane stress and plane strain fracture toughness.
• New options are available for load definition in addition to the existing constant amplitude option: spectrum load history; superposition of load systems (eg residual stress with cyclic load).
• A rainflow counting scheme for random load spectra is included.
• Some new crack-blocks are introduced.
• A new concept of "large" crack-blocks in introduced. Surface based tying is used to tie one crack-block to several elements in the rest of the mesh rather than having a strict one-for-one relationship between crack-blocks and uncracked mesh elements.
• Option to use "retained" nodes for the crack tip model.
• A number of new options are available to control the shape and distribution of elements in the crack front region.
• An adaptive stepping algorithm is introduced to control step sizes between f.e. analyses during growth prediction. Generally this provides more accuracy in calculating N for less f.e. runs compared to the previous fixed step algorithm.
• A numerical integration scheme is introduced for the forward predictor integration algorithm to handle cases where a closed form analytical solution is not possible.
• The integration scheme is converted to double precision.
• Improved control on analysis steps for which j-integrals are extracted (Abaqus interface)
• Use of nodal displacements is introduced:
• use of relative opening displacements to define an "open" or "closed" status at crack front and crack face nodes
• calculation of Ki, Kii and Kiii from nodal displacements (CTOD).
• Option for automatic inclusion of crack face contact (Abaqus interface only).
• Boundary shifting and large crack growth algorithms are introduced.
• Improved options to save f.e. analysis files during a growth analysis.
• User control of output reports and tables
• The initial crack size can now be defined using an absolute size rather than a ratio along an element edge.
• Use of dynamic array allocation to reduce memory requirements.
• Utility program to generate tabular crack growth data from tanh equation data.