Overview
Why Use Zencrack?
There are many reasons, both commercial and technical, for considering the use of Zencrack. Some of those are highlighted here.
Cost benefit
Zencrack provides a state-of-the-art capability for modelling and analysing 3-dimensional cracks, predicting their behaviour under static loading and their growth under both fatigue and time-dependent loading.
By using Zencrack you can:
- increase the efficiency and productivity of your 3D fracture mechanics workforce,
- reduce your pre and post-processing time for 3D finite element crack analysis,
- analyse problems that cannot be tackled using conventional fracture mechanics methods.
In the past, the generation of finite element meshes for 3D fracture mechanics applications was both time-consuming and difficult. The evaluation of stress intensity factors was generally limited to simple planar cracks in 3D structures, usually under mode I loading only. Non-planar crack growth prediction in 3D structures was virtually impossible. Now, Zencrack removes these limitations by providing a fracture mechanics analysis capability that can be used to generate cost-effective solutions to otherwise intractable problems.
Track Record
Zencrack has been in continuous development since 1990 and is proven in numerous applications, including:
- crack growth in turbine blade/disk dovetail connections
- crack growth prediction of sub-surface cracks within a residual stress field
- pressure, thermal transient and creep analyses within power plant components.
Technical Advantages
Apart from its cost-effectiveness and proven track record, there are many sound technical reasons for investing in Zencrack. These include:
- use of industry-standard finite element software as part of the overall solution1:
- complex non-planar crack shapes and geometries can be analysed
- component geometry is general and based on an uncracked f.e. mesh - there is no requirement to have a "simple" component geometry selected from a program supplied list
- the initial crack front shape is not restricted to be straight, circular or elliptic
- the 3D solution makes no assumption regarding plane stress or plane strain2
- loading on the crack may be mixed mode
- growth is calculated at multiple points along a crack front with no forced assumptions about the crack shape; the shape that develops is due to the geometry, loading and materials data
- multiple defects may be included in a component
- a wide range of complex loading can be applied including:
- residual stress from shot peening
- spectrum load files (limited in size only by memory and disk limitations).
Two Levels of Capability
Zencrack provides flexibility with two levels of simulation capability embodied in Zencrack Standard and Professional.
For industries where static loading is important the Standard version can be used to evaluate stress intensity factors using energy release rate and nodal displacement methods. For thermal transients, the instantaneous stress intensities may be evaluated through the transient to steady state conditions. Collapse analyses may also be undertaken allowing generation of data for failure assessments diagrams.
The second level of capability is introduced through Zencrack Professional and provides a facility for 3D non-planar crack growth prediction for cases of fatigue and time-dependent loading. This includes several options for crack growth data definition and a flexible "load system" approach for defining load spectra.
Linear or Non-linear Finite Element Analysis
By interfacing to commercial finite element codes rather than using a proprietary finite element solution, Zencrack is able to take advantage of the many man years of development within these codes and their associated pre and post-processors. Users have at their disposal all of the capabilities within these codes and may include any number of non-linear features in an analysis, in addition to being able to carry out a "standard" linear elastic fracture mechanics analysis. For example:
- non-linear materials, e.g.
- plasticity
- creep
- hyperelastic
- large deformation (e.g. rubber, rolling)
- contact (between components and/or crack face contact)
- plastic collapse.
As well as providing an efficient meshing and analysis capability, Zencrack also carries out significant post-processing of the finite element results.
2. State of stress assumptions are required in the following limited cases:
- when using displacements to calculate stress intensity factors
- when calculating an apparent fracture toughness
- during retardation calculations for the Willenborg retardation model
Zencrack
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