Browsing by Author "Barbosa, Marta Luísa Sousa"
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- Fracture Characterisation of bonded joints between cortical bone tissue and bone cementPublication . Barbosa, Marta Luísa Sousa; Silva, Francisco José Gomes daThe process of evolution has led to the creation of fantastic materials. Bone is one of these materials and has a complex, anisotropic, hierarchical and heterogeneous microstructure, characterised by an excellent mechanical performance. However, as it is an almost fragile material, it often ends up fracturing. These fractures decrease the patient's quality of life and entail high costs for the health system. In order to deal with these fractures, the BoFraPla project arose, which aims to develop a fibrous system for fixing bone fractures. Therefore, in the scope of the activities of this project, the present dissertation emerges, proposing to mechanically characterise the bond between the bone and bone cement. From a thorough literature review, it was found that although the bone cement has been used for more than fifty years, there are few references to its mechanical characterisation and none were found that have made a clear characterisation of the fracture process between the bone and the cement. Hence, in this report, a pure mode I characterisation (tension) through a Double Cantilever Beam (DCB) test and another pure mode II characterisation (shear) through an End-Notched Flexure (ENF) test are presented. In order to overcome the difficulties in monitoring the crack length during the laboratory tests, a method based on the equivalent crack length was used. With this method, the resistance curve was drawn for each specimen and, in most of them, the existence of thresholds was remarkable, which allowed a correct measurement of the fracture energy for each test. In order to validate the results obtained, numerical simulations were performed with cohesive models. Through the results, it was possible to determine that the chosen tests, the defined dimensions and the adopted procedure, can be used to characterise the fracture of these two materials in the studied loading modes.