Evaluación del daño por impacto en laminados de material compuesto mediante la respuesta dinámica
- Autores: Marco Antonio Pérez Martínez
- Directores de la Tesis: Sergio Oller (dir. tes.), Lluís Gil Espert (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2012
- Idioma: español
- Tribunal Calificador de la Tesis: Eugenio Oñate Ibáñez de Navarra (presid.), Federico París Carballo (secret.), Antonio Joaquim Mendes Ferreira (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Composite laminates offer decisive advantages compared to more traditional materials, especially in structural applications where weight is a design-limiting factor. However, they have also shown a susceptibility to impact damage due to the lack of plastic deformation, the low transverse and interlaminar shear strength and the laminar construction to compensate the anisotropic nature of plies. Low-velocity impacts induce a significant internal damage to laminates, causing severe reductions on stiffness, compression strength and structural stability of the structure. Consequently, there is a need to develop methodologies and tools for inspection to allow early detection of structural degradation, in order to prevent premature failure or collapse. Damage detection techniques based on structural dynamic response are presented as an attractive alternative to traditional assessment techniques, among others, because for dynamic response measurement a finite number of reference points are needed. Since there is no need to fully access the structure, it can be monitored with no service interruption. The techniques are based upon the relationship between the modal parameters and the physical properties of the structure, assuming that changes occurred in these properties induced by damage cause measurable variations of the modal parameters. This thesis analyzes the feasibility of using experimental and numerical techniques based on the dynamic response for the detection and location of induced damage, for quantifying the degree of severity and predicting the residual mechanical properties of composite laminates plates after being subjected to a low-velocity impact test. This research presents a mixed experimental and numerical approach. On the one hand there is a rigorous experimental study that includes the evaluation of the impact damage resistance, the induced damage characterization, the quantification of the effects on the dynamic response and the evaluation of residual bearing capacity. The experimental study is completed with a detailed analysis of the effect induced by artificial delaminations in the dynamic response and the residual bearing capacity of laminates. On the other hand, the phenomenon has been simulated mainly by estimating the initiation and propagation of interlaminar damage and equally the induced effects in the dynamic response. As per the numerical approach, composite material is treated as a microstructure in which failure occurs in the interaction among the constituent materials. To reproduce material’s degradation a strategy of localized elastic stiffness reduction has been used, which does not require intervention during the pre-processing phase. Empirical results provide important conclusions concerning the degree of sensitivity and suitability of different modal correlation criteria for the identification of an impact-induced damage. The new correlation criteria defined and the analysis of static and dynamic residual properties have allowed to narrow the range of uncertainty and reduce the current limitation on the maximum allowable compressive deformation of the laminates. The computational tool developed allows simulating the vibrational behavior of composite laminates, defining the material and its state of degradation in the microscale. The results support the feasibility of the microstructural approach to simulate the phenomenon.
