Tesis doctoral de LlorenÁ§ Llopart Prieto
The motivation of this ph.D. Thesis started from the interest of the aeronautical industry to exploit the utilization of crack turning to protect the stiffeners in front of an approaching skin-crack in integral structures by means of a tailored design. The main objective of this ph.D. Thesis was to assess and predict crack turning under nearly in-plane opening mode situations on structures that reproduce aeronautical conditions. The industrial environment in which this work has been carried out requires a fast prediction of the structural behaviour to provide useful inputs to aircraft designers. It is for this reason that the crack turning prediction was investigated by means of linear elastic fracture mechanics and finite element analysis. a screening of existent commercial and non-commercial tools was carried out in respect to their fracture mechanics capabilities on two and three dimensional models, their design abilities, implementation as well as their complexity. Although, there are many software possibilities, only those within the reach of the author were evaluated. This screening and evaluation, after the above definition, resulted in the selection of the commercial analysis tool called stresscheck(r).During this work it has been shown the importance and necessity of a second parameter for the characterisation of the stress field at the crack tip besides the stress intensity factor. Among the different proposed second parameters, the uniform non-singular stress, normal to the crack line and dependent on the type of loading and specimen geometry, i.E. The t-stress, was selected for crack turning predictions due to both calculation simplicity and its independence of the crack tip distance.An important step was the implementation of the t-stress extraction facility in the tool. The assessment of crack propagation on the middle cracked tension and two stringer specimen governed by the paris and forman crack growth regimes was satisfactory compared with experim
Datos académicos de la tesis doctoral «Modelling and analysis of crack turning on aeronautical structures«
- Título de la tesis: Modelling and analysis of crack turning on aeronautical structures
- Autor: LlorenÁ§ Llopart Prieto
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 21/09/2007
Dirección y tribunal
- Director de la tesis
- Marcos Juan Anglada Gomila
- Tribunal
- Presidente del tribunal: Antonio Mateo garcia
- claudio Dalle donne (vocal)
- Baudin de la lastra carmen (vocal)
- bischoffshausen Horst schmidt (vocal)