Fracture control / Damage tolerance
Current activities on Fracture Control / Damage Tolerance areas at ESA include:
The application of fracture control principles for the mitigation of catastrophic and critical hazards is an essential part of the structural verification of spaceflight vehicles, modules, payloads and ground support equipment. Mechanical failures that may result in loss of life, severe injury or major damage to the hardware must be prevented.
For that purpose, damage tolerance principles are applied to ensure that undetected cracks and other defects existing on the structure do not lead to failure within the service life of critical hardware. All structural items whose failure is recognized to result in a catastrophic or critical hazard (e.g. disintegration, loose item, crew impact, loss of critical function, jamming, etc) must be designed and verified according to fracture control principles.
Research and Development activities
The ESACRACK package is the structural analysis software utilized by ESA for damage tolerance evaluation of spaceflight structures. This package developed and distributed by ESA consists of various analysis tools used to generate load and stress spectra, perform fracture mechanics analysis, generate stress intensity factor solutions and to perform fatigue analysis.
ESA is supporting the continuous development of ESACRACK, the structural analysis tools used for damage tolerance verification of spaceflight vehicles and payloads as well as ground support equipment.
Version 4.1.0 of ESACRACK software package was released on 2006. The ESACRACK 4.1.0 package distributed by ESA includes the following tools:
ESA supports also the development of structural software’s and methodologies in the domain of probabilistic fracture mechanics. The stochastic version of ESACRACK, based on ISPUD (developed by Leopold-Franzens University,Innsbruck,Austria) probabilistic software and NASGRO® crack growth analysis software, allows reliability assessments for systems where the structural performance is mainly driven by fatigue crack growth.
Currently the stochastic version of ESACRACK is not foreseen for direct application to design/verification of space projects, but more as a support tool for the definition of deterministic analysis approaches.
FRAMES-2 software is a materials database facility developed by ESA to store and process mechanical test data for metallic and composite materials.
The database includes various data processing functions and allows editing the database by adding new datasets, new materials, calculating deduced data or fitting parameters. Data consultation, plotting and reporting are additional options available.
A web interface to the FRAMES-2 materials database has been developed by ESA, providing simple and easy access to mechanical test data for all costumers.
NOTE: For the moment, only the Crack Growth, Crack Growth Threshold, Fatigue, Static Strength and Fracture Toughness mechanical tests are accessible via the web edition. Additional data will be made available in the future. (http://www.dorea.eu/FRAMES-2)
Last update: 23 August 2007