R&DResearch and development leading to generation of new knowledge, technology and products has always been at the heart of Zentech’s activities. We have over the years developed many novel algorithms and numerical schemes which facilitate efficient simulation procedures. Zentech has participated in a number of funded research projects in the aerospace industry to assess the residual life and durability of components under varied thermal, cyclic, time dependent and dynamic loadings. In the early 1990s, Zentech participated with the Royal Aerospace Establishment based in Farnborough, UK, to develop focussed 3D finite element meshes at the crack front to determine the energy release rate and simulate crack propagation. This eventually led to development of the Zencrack software. In 2000 Zentech participated in a 3 year SBIR funded project with the Air Force Research Laboratory at Wright Patterson Air Force Base, Dayton, Ohio, USA, to further enhance 3D crack propagation in Zencrack by introducing new capabilities including large scale crack advancement and time dependent crack growth prediction. In 2011 Zentech participated in the DISPLACE project led by Rolls-Royce plc and introduced crack growth prediction under full cycle loading with combined cyclic and time varying loads. This was a TSB-funded development of 'technology to increase the life and reliability of advanced lightweight Ni-based gas turbine discs'. Zentech has been incorporating new features in Zencrack continuously to assess the durability and damage tolerance of additive manufactured components, adhesive lap joints and cracking due to corrosion. Zentech also supports independent university R&D activities by providing reduced rate licensing of Zencrack for academic use. Many researchers are using Zencrack to assist with their fracture mechanics analyses, e.g.:
Zentech has always recognised the benefit of consultancy services to the ongoing development of successful software; only through regular application to real-world problems can our programs evolve and continue to be relevant. Our consultancy services on a range of commercially important applications include:
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DISPLACE Project
DISPLACE was a Technology Strategy Board UK Government-funded development (2011) of 'technology to increase the life & reliability of advanced lightweight Ni-based gas turbine discs'.
"The work carried out by Zentech for this project will provide new and enhanced capabilities within the Zencrack software. A significant enhancement will be made to the combined fatigue and time dependent analysis capability for full flight cycle analysis. This includes enhancement in the options for time dependent crack growth laws and the addition of an option for including the effect of minor cycles during the fatigue crack growth calculations. The complex interaction between stress and temperature time histories is treated in a thorough manner with industry-standard options included to define the method of association of temperature with fatigue cycles during evaluation of crack growth rates. Although the framework of this project addresses a specific aerospace requirement, the capabilities introduced in Zencrack are general and can be applied to other industry areas where thermo-mechanical fatigue and high temperature crack growth present significant problems." (Reference: TP/8/MAT/6/I/Q1525K)
WPAFB SBIR Project
"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." (Reference: AFRL-ML-WP-TR-2004-4014)