This work presents an assessment of classical and state of the art reduced order modeling (ROM) techniques to enhance the computational efficiency for dynamic analysis of jointed structures with local contact nonlinearities. These ROM methods include classical free interface method (Rubin method, MacNeal method), fixed interface method Craig-Bampton (CB), Dual Craig-Bampton (DCB) method and also recently developed joint interface mode (JIM) and trial vector derivative (TVD) approaches. A finite element (FE) jointed beam model is considered as the test case taking into account two different setups: one with a linearized spring joint and the other with a nonlinear macroslip contact friction joint. Using these ROM techniques, the accuracy of dynamic behaviors and their computational expense are compared separately. We also studied the effect of excitation levels, joint region size, and number of modes on the performance of these ROM methods.
Component model synthesis (CMS) has been widely used for model order reduction in dynamic analysis of jointed structures with localized non-linearities. The main drawback of these CMS methods is that their computational efficiency largely depends on the size of contact friction interfaces. This work proposes an adaptive reduction approach to improve these CMS based reduction methods in the application to the assembled structure with frictional interfaces.The main
This paper describes a review of the relevant literature about mistuning problems in bladed disc systems, and their implications for the uncertainty propagation associated to the dynamics of aeroengine systems. An emphasis of the review is placed on the developments of the multi-scale computational techniques to increase the computational efficiency for the linear mistuning analysis, especially with the respect to the reduced order modeling techniques and uncertainty quantification methods. The non-linearity phenomenon would not be considered in this paper. The first two parts describe the fundamentals of the mechanics of tuned and mistuned bladed discs, followed by a review of critical research efforts performed on the development of reduced order rotor models. The focus of the fourth part is on the review of efficient simulation methods for the stochastic analysis of mistuned bladed disc systems. After that, we will finally provide a view of the current state of the art associated to efficient inversion methods for the stochastic analysis, followed by a summary.
This work presents a set of analytical design models to predict the electrical and mechanical properties of hybrid carbon nanotubes (CNT)/carbon-fibre (CF)/epoxy composites for potential use in fuselage and airframe constructions against lightning strike. The models are validated by experimental data from open literature. An optimization process is carried out to identify the microstructural configuration of the composite that provides the highest improvement in terms of electrical conductivity for the lowest structural weight in a CFRP fuselage design. The through-the-thickness conductivity of the composite laminate is considerably enhanced by a 2% volume fraction dispersion of CNTs within the matrix resin. The increase in the dielectric properties is accompanied by a moderate improvement of the composite mechanical performance. The hybrid CFRP/CNT composite configuration leads to a weight-efficient design solution for representative fuselage structures.
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