Multi-dimensional models for the global-local analysis of smart layered structures

The present paper presents a multidimensional model for the global-local analysis of smart layered structures. The use of the Carrera Unified Formulation has lead to a general framework for the development of one-, two- and three-dimensional models. The use of the node-dependent kinematic approach makes it possible to easily connect elements with incompatible kinematics, that is, refined kinematic elements can be connected with classical elements without the need of ad hoc connection strategies. The capabilities of this numerical model have been exploited to develop enhanced global-local models for smart layered structures where high-fidelity models are used only in those areas where complex phenomena appear, e.g. around a piezo-patch. The results show the accuracy and efficiency of the present approach and make it suitable for future applications in the design of smart structures

Advanced modeling of embedded piezo-electric transducers for the health-monitoring of layered structures

The present paper presents an innovative approach for the numerical modeling of piezo-electric transducers for the health-monitoring of layered structures. The numerical approach has been developed in the frameworks of the Carrera Unified Formulation. This computational tool allows refined numerical models to be derived in a unified and efficient fashion. The use of higher-order models and the capability to connect different kinematic models using the node-dependent kinematic approach has led to an efficient modeling technique for global-local analysis. This approach can refine the model only in those regions where it is required, e.g., the areas where piezo-electric transducers are placed. The model has been used to study embedded and surface-mounted sensors. The accuracy of the present model has been verified by comparing the current results with numerical and experimental data from the literature. Different modeling solutions have been developed, mixing one-, two- and three-dimensional finite elements. The results show that the use of the present modeling technique allows the computational cost to be reduced with respect to the classical approaches preserving the accuracy of the results in the critical areas

Free vibration analysis of variable angle-tow composite wing structures

This paper investigates the possibility to improve the dynamic response of complex aeronautical structures using variable angle-tow composites. The study has been performed using an innovative numerical approach developed in the framework of the Carrera Unified Formulation able to study laminates with curvilinear fibres whose trajectories can be arbitrarily defined. Refined kinematic structural models have been used to deal with the complex behaviour of such structures. Several cases have been investigated in order to validate this approach and the results have been compared with those from classical modelling approaches. Simple beam models and complex wing structures, have been considered. The effects of different fibres-paths have also been studied and compared. The results confirm that an appropriate tow lay-up can be used to improve the performances of wing structures, i.e. innovative design solutions can be achieved

Free vibration analysis of locally damaged aerospace tapered composite structures using component-wise models

This work presents the free vibration analysis of tapered aircraft structures made of composite and metallic materials, with reference to global and local damage. A refined one-dimensional model, developed in the framework of the Carrera Unified Formulation, has been used to provide a detailed description of structures. Multi-component aeronautical structures have been modeled adopting Lagrange polynomials to evaluate the displacement field over the cross-section. Each component has been described through the component-wise approach, with its own geometrical and mechanical characteristics. The effects of localized damage have been investigated, thanks to the accuracy of the layer-wise models adopted. The model has been assessed by comparing the results with classical FE models. The results show that the present approach provides an accurate solution for the free vibration analyses of complex structures and is able to predict the consequences of a global or local failure of a structural component. The computational efficiency and the accuracy of the model used in this work can be exploited to characterize the dynamic response of complex composite structures considering a large number of damage configurations

Multidimensional models for double-swept helicopter blades

This paper presents multidimensional finite element models for the analyses of modern helicopter blades. The methodology enables finite elements with different dimensionality to be joined together in a consistent fashion. The formulation exploits the unique feature of a special class of refined beam elements, which have pure displacements as unknowns. This property makes it possible to connect beam and solid elements at node levels without the need for complicated mathematical formulations. Various problems in the modeling of realistic blades can be tackled with ease such as the application of nonclassical constraints. All physical surfaces of the structure can be modeled regardless of which finite element is used for discretizing the blade portion. Thus, three-dimensional stress states can be readily obtained by avoiding further postprocessing operations. The multidimensional models have been verified with experimental results and validated with beam and shell finite element solutions available in the literature by considering tip-swept blades with rectangular cross sections. The methodology has been then applied to a double-swept blade with a realistic profile

Analysis of tapered composite structures using a refined beam theory

This work presents some static analyses on reinforced thin-walled tapered structures made of composite material. These applications are performed through a refined one-dimensional model based on the Carrera Unified Formulation. This formulation uses polynomial expansions to describe the displacement field over the cross-section of the beam. In this way, a quasi three-dimensional solution can be obtained. In the present work the cross-sectional kinematic has been described using the Lagrange polynomials. The use of such models allows any component of the structure to be modelled separately and then the complex structure can be obtained thanks to the so-called component-wise approach. Different aeronautical structural components, gradually more complex, have been studied. The stress and displacement fields due to simple loads have been obtained. The results have been compared with those obtained by means of a commercial FEM tools using one-, two- and three-dimensional elements. The results obtained show how the present approach can deal with complex structures such as tapered aeronautical components. The use of refined beam models allows complex stress fields to be accurately evaluated that is composite materials can be investigated

Finite element models with node-dependent kinematics for the analysis of composite beam structures

This paper presents refined one-dimensional models with node-dependent kinematics. The three-dimensional displacement field is discretized into two domains, namely cross-section domain and axis domain. The mechanical behaviors of the beam can be firstly captured by the cross-section functions then interpolated by the nodal shape functions of the beam element. Such a feature makes it possible to adopt different types of cross-section functions on each element node, obtaining node-dependent kinematic finite element models. Such models can integrate Taylor-based and Lagrange-type nodal kinematics on element level, bridging a less-refined model to a more refined model without using special coupling methods. FE governing equations of node-dependent models are derived by applying the Carrera Unified Formulation. Some numerical cases on metallic and composite beam-like structures are studied to demonstrate the effectiveness of node-dependent models in bridging a locally refined model to a global model when local effects should be accounted for