Improved Life Prediction of Turbine Engine Components Using a Finite Element Based Software Called Zencrack
Abstract
This report was developed under SBIR contract. The objective of this SBIR was to incorporate new features in the fracture mechanics software, Zencrack, including cyclic and time-dependent load spectra, residual stress distributions, generalized Willenborg retardation, user-defined crack fronts (e.g. for transition from semi-elliptic to through cracks) and automatic large 3-D crack growth. Zencrack was also interfaced to ANSYS in addition to enhanced interfaces to ABAQUS and MSC.MARC. Zencrack models crack fronts by replacing solid elements in finite element (FE) meshes by detailed regions of crack-blocks. The CTOD method was added to the existing 3 D J-integral facility to compute stress intensity factors (SIF) and direction of crack propagation under mixed mode LEFM loading. Numerical crack growth integration algorithms were developed for superposition load systems (e.g. static residual stresses and cyclic loading). New 3-D meshing features to minimize element distortion were developed including large crack-blocks with transition elements at crack block tied surfaces, mesh relaxation , crack-block boundary shifting and boundary flipping of through cracks. Fatigue and time-dependent crack growth data can now be specified as a function of stress ratio and temperature using Paris Law segment data, tabular data or in a Zencrack user subroutine. Validation of the software was conducted by benchmarking against AFGROW software, data and theoretical solutions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2003
- Accession Number
- ADB296907
Entities
People
- Amiya Basu
- Chris Timbrell
- Gerry Cook
- Partha Chakrabarti
- Ramesh Chandwani