Alfonso Pagani

Alfonso Pagani
Politecnico di Torino | polito · DIMEAS - Department of Mechanical and Aerospace

Doctor of Philosophy

About

171
Publications
21,319
Reads
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2,509
Citations
Additional affiliations
April 2015 - September 2015
Turin Polytechnic University in Tashkent
Position
  • Professor
January 2015 - June 2016
Politecnico di Torino
Position
  • Research Assistant
January 2012 - December 2014
Politecnico di Torino
Position
  • PhD Student

Publications

Publications (171)
Article
Full-text available
In this paper, the use of the node-dependent kinematics concept for the geometrical nonlinear analysis of composite one-dimensional structures is proposed With the present approach, the kinematics can be independent in each element node. Therefore the theory of structures changes continuously over the structural domain, describing remarkable cross-...
Article
Full-text available
This work intends to present a novel numerical approach for studying the vibration behaviours of variable angle tow (VAT) composite structures in their quasi-static nonlinear equilibrium states. This methodology is able to predict the buckling load, to investigate the natural frequencies variation for progressively higher loads, and to provide a me...
Article
This paper presents the analysis of free vibration and stress state of steel–concrete composite beams, using high-order theories and closed-form solutions based on Carrera unified formulation (CUF). The governing differential equations are formulated in terms of fundamental nuclei via CUF and the longitudinal differential problem is solved analytic...
Article
The present work provides a numerical model for carrying out virtual Vibration Correlation Technique (VCT) for computing the buckling load, identifying the natural frequencies variation with progressive higher applied load, and providing an efficient means for the verification of the experimental VCT results. The presented nonlinear approach is bas...
Article
Based on the Carrera unified formulation (CUF) and first-invariant hyperelasticity, this work proposes a displacement-based high order one-dimensional (1 D) finite element model for the geometrical and physical nonlinear analysis of isotropic, slightly compressible soft material structures. Different strain energy functions are considered and they...
Article
This paper proposes an equivalent single-layer approach for modeling laminated structures, where the number layers to be considered as a single one is chosen a priori by the user. Lagrange points are set to locate and, eventually, join equivalent single-layer and layer-wise tenchiques by imposing displacement continuity in the thickness direction....
Article
Full-text available
This work investigates quasi‐static crack propagation in specimens made of brittle materials by combining local and non‐local elasticity models. The portion of the domain where the failure initiates and then propagates is modelled via three‐dimensional bond‐based peridynamics. On the other hand, the remaining regions of the structure are analyzed w...
Article
The structural analysis of ultra-lightweight flexible shells and membranes may require the adoption of complex nonlinear strain-displacement relations. These may be approximated and simplified in some circumstances, e.g., in the case of moderately large displacements and rotations, in some others may be not. In this paper, the effectiveness of vari...
Preprint
This article investigates the large deflection and post-buckling of composite plates by employing the Carrera Unified Formulation (CUF). As a consequence, the geometrically nonlinear governing equations and the relevant incremental equations are derived in terms of fundamental nuclei, which are invariant of the theory approximation order. By using...
Preprint
The structural analysis of ultra-lightweight flexible shells and membranes may require the adoption of complex nonlinear strain-displacement relations. These may be approximated and simplified in some circumstances, e.g., in the case of moderately large displacements and rotations, in some others may be not. In this paper, the effectiveness of vari...
Article
Multilayer perceptrons are utilized in this work for vibration-based damage detection of multi-component aerospace structures. A back-propagation algorithm is utilized along with Monte Carlo simulations and advanced structural theories for training Artificial Neural Networks (ANN’s), which are able to detect and classify local damages in structures...
Article
This paper shows some important results from a test campaign conducted on the Dardo Aspect, a wet-laminate full-composite very-light airplane (VLA). Both static and dynamic experimental analyses are carried out. All the results and methodologies utilized in this paper take into account compliance with certification requirements. Particular attentio...
Article
Full-text available
The geometrical nonlinear effects caused by large displacements and rotations over the cross section of composite thin-walled structures are investigated in this work. The geometrical nonlinear equations are solved within the finite element method framework, adopting the Newton–Raphson scheme and an arc-length method. Inherently, to investigate cro...
Preprint
This article investigates the large deflection and post-buckling of composite plates by employing the Carrera Unified Formulation (CUF). As a consequence, the geometrically nonlinear governing equations and the relevant incremental equations are derived in terms of fundamental nuclei, which are invariant of the theory approximation order. By using...
Article
This article investigates the large deflection and post-buckling of composite plates by employing the Carrera Unified Formulation (CUF). As a consequence, the geometrically nonlinear governing equations and the relevant incremental equations are derived in terms of fundamental nuclei, which are invariant of the theory approximation order. By using...
Article
Full-text available
In the framework of finite elements (FEs) applications, this paper proposes the use of the node-dependent kinematics (NDK) concept to the large deflection and post-buckling analysis of thin-walled metallic one-dimensional (1D) structures. Thin-walled structures could easily exhibit local phenomena which would require refinement of the kinematics in...
Article
This work focuses on the study of composite metamaterials to be employed as possible lightweight insulation systems for noise and vibrations. In particular, the dispersion relations are derived by applying the Bloch-Floquet theory to the unit cell of the periodic microstructure. Advanced beam finite elements based on Carrera Unified Formulation are...
Article
This work proposes an alternative approach for the nonlinear analysis of 2D, thin-walled lattice structures. The method makes use of the well-established Carrera Unified Formulation (CUF) for the implementation of high order 1D finite elements, which lay along the thickness direction. In this manner, the accuracy of the mathematical model does not...
Article
This research work deals with the buckling load prediction of reinforced laminated composite panels of aeronautical interest. Being subjected to pure compression, these panels are characterized by stable post-buckling. Thus, the vibration correlation technique (VCT) is utilized herein as an effective nondestructive means to extrapolate critical loa...
Article
By making use of high order shell models, the present work discusses frequency and mode change of thin structures subjected to large displacements and rotations. The models are implemented in the domain of the well-established Carrera Unified Formulation (CUF) and employ the full Green-Lagrange strain tensor, in a total Lagrangian scenario. In this...
Article
Full-text available
The usage of printed composites in the aerospace industry has been steadily increasing over the last years. Especially, 3D printers and automatic fibre placement machines have allowed the introduction of Variable Angle Tow (VAT) composites, which theoretically offer greater tailoring capabilities than classic composite laminates. Nevertheless, the...
Article
This paper deals with the evaluation of time response analyses of typical aerospace metallic structures. Attention is focussed on detailed stress state distributions over time by using the Carrera Unified Formulation (CUF) for modeling thin-walled reinforced shell structures. In detail, the already established component-wise (CW) approach is extend...
Article
This paper presents advanced-kinematics beam models to compute the dispersion characteristics of one-dimensional guides. High-order functions are used to interpolate the primary variables above the waveguide cross-section and along its axis. Taylor- and Lagrange-type bi-dimensional expansions are employed to describe the section deformation, while...
Article
The present paper presents the evaluation of three-dimensional (3D) stress distributions of shell structures in the large displacement and rotation fields. The proposed geometrical nonlinear model is based on a combination of the Carrera Unified Formulation (CUF) and the Finite Element Method (FEM). Besides, a Newton-Raphson linearization scheme is...
Article
Full-text available
The present work investigates the possibility of reducing the strain/stress concentrations in a open-hole plate using localized 3D printed carbon fiber reinforcements. Several reinforcement strategies have been investigated exploiting the capabilities of a recent additive manufacturing process, the carbon filament fabrication, that allows continuou...
Article
In this work, the effect of the fiber orientation on the mechanical response of variable angle tow (VAT) panels is investigated. A computationally efficient high-order one-dimensional model, derived under the framework of the Carrera unified formulation (CUF), is used. In detail, a layerwise approach is adopted to predict the complex phenomena that...
Article
Peridynamics is a non‐local theory which has been successfully applied to solid mechanics and crack propagation problems over the last decade. This methodology, however,may lead to large computational calculations which can soon become intractable for many problems of practical interest. In this context, a technique to couple –in a global/local sen...
Article
This work wants to investigate the soundproofing level of passive acoustic metamaterials made of Melamine Foam and cylindrical Aluminum inclusions. Latest research shows promising acoustical possibilities on controlling certain frequencies, varying their geometry or material configuration. Typically, acoustic metamaterials are plates with inclusion...
Article
Additive manufacturing brought to the emergence of a new class of fiber-reinforced materials; namely, the Variable Angle Tow (VAT) composites. Automated fiber placement machines allow the fibers to be relaxed along curvilinear paths within the lamina. In theory, the designer can conceive VAT structures with unexplored capabilities and tailor materi...
Chapter
This paper presents the free vibration and static analysis of composite box beam using refined beam theory. The structural model based on one-dimensional (1D) is derived in the Carrera Unified Formulation (CUF) framework. The principle of virtual displacement has been used along with CUF to formulate the finite element arrays in the terms of fundam...
Article
The present paper aims at studying composite cambered structures, tracking the seminar work “Rotating Blade Vibration Analysis Using Shells” presented by Leissa in Journal of Engineering for Power, in 1982, devoted to homogeneous metallic blades. A refined unidimensional (1D) formulation is here implemented to overcome the limitations of classical...
Article
This research work deals with the analysis of elastic shell structures in the large displacement and rotation field adopting one-dimensional (1D) and two-dimensional (2D) unified models. Namely, higher order beam and shell theories accounting for geometrical nonlinearities are formulated by employing a unified framework based on the Carrera unified...
Article
The nonlinear mechanical response of highly flexible plates and shells has always been of primary importance due to the widespread applications of these structural elements in many advanced engineering fields. In this study, the Carrera Unified Formulation (CUF) is used in a total Lagrangian framework to analyze the large-deflection and post-buckli...
Article
An advanced modeling technique for hygro-mechanical analyses has been discussed in the present work. A three-dimensional closed-form solution of the diffusion equation has been developed and used to evaluate the time evolution of the moisture concentration in a composite coupon. A refined kinematic one-dimensional model, derived in the framework of...
Article
Full-text available
In this work, a unified formulation of full geometrically nonlinear refined shell theory is developed for the accurate analysis of highly flexible shell structures. The tensor calculus is utilized to explicitly derive the linear and nonlinear differential operator matrices of the geometrical relation in the orthogonal parallel curvilinear coordinat...
Article
Full-text available
Shear and membrane locking phenomena are fundamental issues of shell finite element models. A family of refined shell elements for laminated structures has been developed in the framework of Carrera Unified Formulation, including hierarchical elements based on higher-order Legendre polynomial expansions. These hierarchical elements were reported to...
Article
Full-text available
Natural frequencies and mode shapes are functions of the equilibrium state. In the large displacement regime, pre-stresses may modify significantly the modal behaviour of structures. In this work, a geometrical nonlinear total Lagrangian formulation that includes cross-sectional deformations is developed to analyse the vibration modes of composite...
Preprint
Full-text available
In this work, a unified formulation of full geometrically nonlinear refined shell theory is developed for the accurate analysis of highly flexible shell structures. The tensor calculus is utilized to explicitly derive the linear and nonlinear differential operator matrices of the geometrical relation in the orthogonal parallel curvilinear coordina...
Preprint
In this work, a uni�ed formulation of full geometrically nonlinear re�ned shell theory is developed for the accurate analysis of highly flexible shell structures. The tensor calculus is utilized to explicitly derive the linear and nonlinear differential operator matrices of the geometrical relation in the orthogonal parallel curvilinear coordinate...
Conference Paper
Based on the well-known nonlinear hyperelasticity theory and by using the Carrera Unified Formulation (CUF) as well as a total Lagrangian approach, the unified theory of slightly compressible elastomeric structures including geometrical and physical nonlinearities is developed in this work. By exploiting CUF, the principle of virtual work and a fin...
Article
This paper applies the isogeometric analysis (IGA) based on unified one-dimensional (1D) models to study static, free vibration and dynamic responses of metallic and laminated composite straight beam structures. By employing the Carrera Unified Formulation (CUF), 3D displacement fields are expanded as 1D generalized displacement unknowns over the c...
Article
This paper introduces a user-friendly tool for accurate stress prediction in laminate shell models in ABAQUS. The aim is to provide users with a code for the fast computation of three-dimensional solutions that overcome the limitations of classical shell models and facilitate the use of advanced composite failure criteria consistently. The methodol...
Article
Full-text available
This paper intends to establish a unified theory of structures based on the micropolar elasticity (ME). ME allows taking into consideration the microstructure of the material, through the adoption of four additional material parameters. In this way, the size-effects of the structure can be caught. The proposed model is developed in the domain of th...
Article
The prediction of the actual stress fields in real structural applications is still not completely resolved, especially when dealing with composite structures. The geometrical complexity of laminate parts and the multiple length scales which are involved in the problem lead to a severe tradeoff between accuracy and computational costs. Consequently...
Article
This paper investigates the consistency and compatibility of various assumptions and strain measurements in a large displacements/geometric nonlinear analysis of beams and thin-walled structures. For this purpose, a refined beam model with enhanced three-dimensional accuracy is employed in a total Lagrangian scenario. This model is developed in the...
Article
The present work introduces a numerical approach for the study of the free-edge effects that arise in generic laminated composites with arbitrary geometries. The model is based on the use of a higher-order beam theory that employs only displacement unknowns over the cross-section domain, the so-called Lagrange expansion (LE). This allows for the re...
Conference Paper
Full-text available
The design and certification process of aerospace structures requires a detailed stress characterization. Nevertheless, the complexity of the aircraft structures and the use of composite materials can significantly increase the computational costs of the models. This work proposes a global/local modelling strategy to set up an high-order model only...
Article
This paper proposes a geometrically nonlinear three-dimensional formalism for the static and dynamic study of rotor blades. The structures are modeled using high-order beam finite elements whose kinematics are input parameters of the analysis. The displacement fields are written using two-dimensional Taylor- and Lagrange-like expansions of the cros...
Article
Accurate predictions of the in-service nonlinear response of highly flexible structures in the geometrically nonlinear regime are of paramount importance for their design and failure evaluation. This paper develops a unified formulation of full geometrically nonlinear refined plate theory in a total Lagrangian approach to investigate the large-defl...
Article
Addressing the need for more computationally efficient and accurate simulation tools for Lamb wave-based structural health monitoring (SHM) systems, this paper proposes the use of refined theories for the study of the wave propagation phenomena in thin-walled structures. When dealing with complex structures, classical plate models can be insufficie...
Article
The design and analysis of aerospace structures requires a detailed evaluation of stresses. Nevertheless, the complexity of large structures and the use of composite materials can significantly increase the computational costs of the models. The computational burden of such analyses can be reduced by a suitable global/local approach developed in a...
Article
This work focuses on the assessment of a novel so-called “homogenization method” allowing to transform a heterogeneous material with inclusions or holes into an equivalent homogeneous material with equal mechanical behavior. The aim is to avoid meshing holes of the real material in finite-element codes, thus improving computation time for further a...
Article
The accurate representation of the 3D stress fields at the bonded areas of adhesive joints is essential for their design and strength evaluation. In the present study, higher-order beam models developed in the framework of the Carrera Unified Formulation are employed to reduce the complexity and computational cost of numerical simulations on adhesi...
Article
Highly flexible laminated composite structures, prone to suffering large-deflection and post-buckling, have been successfully employed in a number of scenarios. Therefore, accurate predictions of their stress distributions in the geometrically nonlinear analysis are of paramount importance for their design and failure evaluation. In this paper, for...
Preprint
Full-text available
Highly flexible laminated composite structures, prone to suffering large-deflection and post-buckling, have been successfully employed in a number of scenarios. Therefore, accurate predictions of their stress distributions in the geometrically nonlinear analysis are of paramount importance for their design and failure evaluation. In this paper, for...
Article
Full-text available
This paper deals with the investigation of the static and dynamic behaviors of composite leaf spring landing gears during the landing phase of an aircraft. An accurate simulation of the overall landing gear mechanism needs to be performed in order to evaluate the forces that result on the fuselage during the impact of the aircraft on the ground. Th...
Chapter
This chapter proposes a numerically efficient method to simulate Lamb waves in laminated structures in the framework of structural health monitoring (SHM). Due to the high frequencies involved in Lamb wave problems, time-domain analyses call for very fine spatial and temporal discretizations of the numerical model. As a consequence, standard models...
Article
Full-text available
The formulation of a family of advanced one-dimensional finite elements for the geometrically nonlinear static analysis of beam-like structures is presented in this paper. The kinematic field is axiomatically assumed along the thickness direction via a Unified Formulation (UF). The approximation order of the displacement field along the thickness i...
Article
This paper proposes an application of already established higher-order models and, namely, investigates the free vibration analysis of civil engineering structures subjected to nonstructural masses. The refined one-dimensional theories adopted are based on the Carrera unified formulation (CUF). The stiffness and mass matrices are obtained by means...
Conference Paper
Full-text available
In many engineering applications, such as civil, mechanical and aerospace, large displacements and rotations may occur within the working composite structures, due to the extreme loading conditions that may occur during service. This afflicts the equilibrium states of the structures and could change them, eventually, in a catastrophic manner. There...
Conference Paper
The formulation of simplified models in the description of flow fields can be highly interesting in many complex network such as the circulatory system. This work presents a refined one-dimensional finite element model with node-dependent kinematics applied to incompressible and laminar flows. In the framework of 1D-FE modelling, this methodology i...
Conference Paper
Full-text available
An important role in the design of structure is represented by the buckling analysis. The loading and service conditions, in which structures usually work, may significantly afflict their equilibrium state. This aspect often forces the design engineers to perform an accurate buckling analysis, in order to calculate critical loads of the structure....
Conference Paper
This work explores the effects of geometrical nonlinearities in the vibration analysis of rotating structures and helicopter blades. Structures are modelled via higher-order beam theories with variable kinematics. These theories fall in the domain of the Carrera Unified Formulation (CUF), according to which the nonlinear equations of motion of rota...
Conference Paper
A novel approach for the analysis of the non-linear behavior of bio-structures is presented here. This method is developed in the framework of the Carrera Unified Formulation (CUF), a higher-order 1D theory according to which the kinematics of the problem depends on the arbitrary expansion of the generalized unknowns. Taylor-like (TE) and Lagrange-...
Article
In this article, the mechanical behavior of three-dimensional curved beams is investigated through closed-form solution as well as one-dimensional finite elements based on Carrera’s Unified Formulation (CUF). CUF is a hierarchical formulation in which the approximation order of the displacement field is a free parameter of the analysis. Therefore,...
Article
Towards improving the numerical efficiency in the analysis of multi-layered shell structures with the finite element (FE) method, an adaptable two-level mathematical refinement approach is proposed for refined curvilinear shell elements. Based on Carrera Unified Formulation (CUF), the approximation of displacement functions of shell elements can be...
Article
This article presents an approach to obtain refined beam models with optimal numerical efficiency. Hierarchical Legendre Expansions (HLE) and Node-dependent Kinematics (NDK) are used in combination to build efficient global-local FE models. By relating the kinematic assumptions to the selected FE nodes, kinematic refinement local to the nodes can b...
Article
Full-text available
This paper deals with the investigation of normal modes change of metallic structures, when subjected to geometrical nonlinearities in the large displacement/rotations field. Namely, a unified framework based on the Carrera Unified Formulation (CUF) and a total Lagrangian approach are employed to formulate higher order beam theories including geome...
Article
This paper extends the use of one-dimensional elements with node-dependent kinematics to the analysis of Stokes flows. According to the Carrera Unified Formulation, the primary variables of the flow, velocity and pressure, are expressed as arbitrary expansions of the generalized unknowns. The novel implementation proposed in this work allows to inc...
Article
This paper presents a novel mixed one-dimensional formulation based upon Reissner's mixed variational theorem for the accurate stress analysis of general multilayered beam problems. Carrera's unified formulation is recalled to generate a class of theory of structure that assumes both displacements and stresses over the cross section of the beam. On...
Article
Full-text available
This paper investigates geometrically nonlinear effects due to large deformations over the cross sections of beam-like and shell-like structures. Finite elements are used to provide numerical solutions along with the Newton–Raphson technique and the arc-length method. Refined theories able to capture cross-sectional deformation are constructed by r...