Modelo estocástico de hueso cortical de costilla humana para la predicción de fracturas mediante emisión acústica
- Autores: Silvia Garcia Vilana
- Directores de la Tesis: David Sánchez Molina (dir. tes.), Juan Velázquez Ameijide (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2021
- Idioma: español
- Materias:
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- Resumen
In this document, a non-linear constitutive model with micro-cracking and irreversibility is proposed for cortical bone of the human rib, extended with a stochastic fracture model, based on acoustic emission. Both models are innovative and describe the behavior of the human rib from the zero-load to macroscopic fracture. Experimentally, the models have shown to describe adequately the mechanical behavior of the rib, even in the non-elastic zone, where irreversible processes have been mainly associated with the propagation of micro-cracks through the material. Furthermore, the constitutive model is thermodynamically consistent, showing a notable increase in entropy as cracking process goes on, a region in which, in turn, a notable asymptotic increase in the released energy by the material has been observed in the form of waves, detected by the acoustic emission technique.
In addition, the constitutive parameters of the model show significant correlation both with anthropometric variables and with micro-structural parameters, such as density, fractal dimension or mineral content, pointing to a clear importance of micro-structure in the behavior of cortical bone. Thus, the quenched disorder parameter, which represents the micro-structural damage previous to failure and which has been introduced into the model by means of the Statistical Mechanics, has shown to have a great influence of age. Likewise, a relationship has also been found between the mineralization of the sample and the possible paths that the main crack can take in its progression through the osteon network. The number of paths has been determined by means of combinatorics.
On the other hand, the stochastic fracture model adequately and quantitatively predicts the occurrence of acoustic signals or hits associated with the stress level introduced into the sample, being one of the first models developed for bone.
