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  • Towards damage quantification caused by drilling in fibre composite laminates
    Publication . Alves, M. S. F.; Barbosa, Inês; Bragança, Ivo; Loja, Amélia
    Drilling operations are a very frequent need when one needs to connect diferente components in a structure, regardless the nature of the materials involved. When these components are total or partially made of composite materials, this manufacturing operation requires a particular care, as the heterogeneous character of composites makes them especially prone to delamination or fibre pulling-out. These undesirable situations, not only contribute to reduce the stiffness/strength of the material in the drilled region neighbourhood, but they may even lead to a subsequent damage propagation and failure. It is therefore important to improve drilling processes efficiency from the damage minimization perspective. To this purpose, the characterization of the drilling parameters influence in a cross-relation to the composite material characterization may be a relevant contribution. With the present work, one intends to present preliminary results associated to the experimental procedure that will enable the characterization of the influence of drilling parameters and of material and geometrical specimen parameters on the drilling affected areas. The information acquisition of the affected areas is carried out through thermographic digital images. A set of illustrative cases is presented and preliminar conclusions are drawn.
  • Towards damage quantification caused by drilling in fibre composite laminates
    Publication . Alves, M. S. F.; Barbosa, Inês; Bragança, Ivo; Loja, Amélia
    Drilling operations are a very frequent need when one needs to connect diferente components in a structure, regardless the nature of the materials involved. When these components are total or partially made of composite materials, this manufacturing operation requires a particular care, as the heterogeneous character of composites makes them especially prone to delamination or fibre pulling-out. These undesirable situations, not only contribute to reduce the stiffness/strength of the material in the drilled region neighbourhood, but they may even lead to a subsequent damage propagation and failure. It is therefore important to improve drilling processes efficiency from the damage minimization perspective. To this purpose, the characterization of the drilling parameters influence in a cross-relation to the composite material characterization may be a relevant contribution. With the present work, one intends to present preliminary results associated to the experimental procedure that will enable the characterization of the influence of drilling parameters and of material and geometrical specimen parameters on the drilling affected areas. The information acquisition of the affected areas is carried out through thermographic digital images. A set of illustrative cases is presented and preliminar conclusions are drawn.
  • An assessment of thermally influenced and delamination-induced regions by composites drilling
    Publication . Loja, Amélia; Alves, M. S. F.; Bragança, Ivo; Rosa, R. S. B.; Barbosa, Inês; Barbosa, Joaquim
    The connection among different structural components may be promoted by several means. Among these, if one considers mechanical connections, it becomes often necessary to drill the components. When these structures are total or partially made of composite materials, this drilling operation imposes a particular care, due to its heterogeneous character highly prone to delamination or fibre pulling-out. Under these circumstances, not only will the stiffness and strength of the material be reduced in the drilled region neighbourhood, but ultimately a more worrying situation may arise if specific conditions exist to enable propagation and subsequent failure. It is therefore important to improve the drilling processes efficiency from the damage minimization perspective. To this purpose, the characterization of the drilling parameters influence in a cross-relation to measurable resulting effects may be a relevant contribution. With the present work, one intends to characterize how different drilling parameters may affect the surrounding region, either from an induced damage quantification perspective as well as from a thermally affected area characterization. The information acquisition of the affected areas was carried out both through scans and thermographic digital videos and images. A set of illustrative cases is presented to support the conclusions.