Free Vibrations of Damaged Aircraft Structures by Component-Wise Analysis

By adopting advanced beam models, this paper presents free vibration analyses of metallic aircraft structures affected by local damages. Refined theories are developed within the framework of the Carrera unified formulation, according to which any-order two-dimensional and one-dimensional theories of structures can be implemented in a hierarchical and unified manner. By employing Lagrange polynomials to expand the generalized displacement field, component-wise models of aircraft structures are implemented in this work. The component-wise approach provides a detailed physical description of multicomponent structures, since each component can be modeled with its own geometrical and mechanical characteristics; that is, no reference surfaces and axes, as well as no homogenization techniques, are employed. This characteristic allows accurate modeling of global and local damages within the structure. The results show that the proposed refined one-dimensional models can deal with the free vibration analysis of damaged aircraft structures as accurately as the shell and solid models. Moreover, thanks to the computational efficiency of the Carrera unified formulation, component-wise models are good candidates for providing the vibration characteristics of structures for a wide range of damage scenarios in order to create databases able, for example, to train neural network for damage detection.