Durability & damage analysis

Z-post is a general purpose post-processing package designed to act on any type of data resulting from a Finite Element Analysis. Initially developed to post-process Zébulon’s results, Z-post is now a generic post-processing software application interfaced with the major FEA codes.

Z-post contains a large collection of “processes” for efficient treatment and analysis of FEA results, with special attention given to life estimation and damage models. Z-post acts on Finite Element calculation results and operates on data known at different structural locations: nodes, Gauss points, elements and a collection of time steps.

Global and local post-processing

Global post-processing operates, for a given time step, on a set of variables and a region of the mesh. The predefined treatments include the computation of the spatial average (needed for homogenization techniques, mesh-independent methods), brittle damage models for metals or ceramics (Weibull, Beremin, Batdorf probabilistic models) and many others.
Local post-processing inputs are variable histories at points (nodes or Gauss points). User-defined series of treatments are applied to produce the final result. The currently implemented collection of post-processing ranges from elementary operators such as max, min, norm, mises and trace, to higher level models: creep models, classical HCF (Sines, Crossland, Dang Van), or strain, stress-based and mixed LCF fatigue models (Manson-Coffin, Chaboche, SWT, Sehitoglu), taking into account the creep-fatigue interaction when necessary. Local post-processing computations are fully parallelized for optimal performances.

Fatigue lifetime estimation models

Z-post includes a number of advanced models and algorithms for creep-fatigue life estimation, capable of simulating most key experimental observations:

valid in both LCF and HCF regimes (i.e., the entire S-N curve)
multiaxial capabilities
modeling of the mean stress influence (Haigh diagram, loading factor influence on S-N curve)
possible coupling with creep damage to account for frequency effects
possible nonlinear accumulation of damage for the correct representation of experimentally observed effects.

Very efficient algorithms are available in Z-post to compute the amplitude and extract cycles from a complex non-proportional 3D stress history (multiaxial rainflow method).

User extensions

Users have several possibilities to extend the existing code capabilities:

using the process function, allowing the introduction of a new model by its mathematical expression directly in the input file
by means of the high level scripting language based on C++, giving access to internal utility and math objects (ARRAY, LIST, VECTOR, MATRIX, TENSOR, etc.)
by means of a Plug-in mechanism that gives access to the Object Oriented architecture of Z-post and thus allows an unlimited number of user extensions