S. Lenci

S. Lenci
Università Politecnica delle Marche | Università degli Studi di Ancona · Department of Construction, Civil Engineering and Architecture (DICEA)

full professor

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410
Publications
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Publications

Publications (410)
Article
Modal interactions are pervasive effects that commonly emerge in nanomechanical systems. The coupling of vibrating modes can be leveraged in many ways, including to enhance sensing or to disclose complex phenomenologies. In this work we show how machine learning and data-driven approaches could be used to capture intermodal coupling. We employ a qu...
Article
The wave propagation problem in a second-order nonlinear PDE, with specific reference to a mechanical system consisting of a taut cable, or string, resting on a piecewise linear foundation is investigated, without and with a distribute transversal load. The piecewise nature of the problem offers a sufficiently simple kind of nonlinearity as to perm...
Article
In this paper, the dynamic characterisation of the civic bell-tower of Rotella (a small village in the Marche region, Central Italy) is presented. The tower after being monitored, using four tri-axial piezo-electric accelerometers, and obtaining its dynamic characteristics, was modelled through a finite element software. The difference between meas...
Article
On the Italian territory, there are many monumental structures that need to be preserved. Given their great historical and architectural value, it is essential to use minimally invasive, but effective, techniques able to evaluate their current structural capabilities and monitor their structural health. The technique that currently appears most app...
Preprint
An adaptative phase-space discretization strategy for the global analysis of stochastic nonlinear dynamical systems with competing attractors considering parameter uncertainty or noise is proposed. The strategy is based on the classical Ulam method. The appropriate transfer operators for a given dynamical system are derived and applied to obtain an...
Preprint
This paper explores the influence of uncertainties and noise on the global dynamics of nonlinear systems, with emphasis on the basins and attractors’ topology and on the dynamic integrity of coexisting solutions. For this, the adaptive phase-space discretization strategy proposed in Part I [1] is employed. Two well-known archetypal oscillators foun...
Article
This paper investigates the advantages or issues of different reduced-order models (ROMs) for the analysis of elastic cables hanging between two supports at different height. The cable is considered immersed in still fluid and under the action of an imposed boundary motion at the upper support. Nine ROMs are explored, obtained from the combination...
Preprint
Full-text available
The wave propagation problem on a taut cable resting on a bilinear substrate is investigated, without and with a distribute transversal load. The piecewise nature of the problem offers a sufficiently simple kind of nonlinearity as to permit a closed form solution both for the wave phase velocity and the wave form. We show that the solution depends...
Article
The exact analytical solution of a system made of two coupled Duffing oscillators is obtained. The mathematical solution is illustrated by means of some examples aimed at showing the dynamical phenomena occurring in the considered system. Frequency response curves are reported for different value of the parameters, highlighting the effects of the l...
Article
Full-text available
This work investigates the dynamics of a hinged-simply supported beam with an axial spring in the neighborhood of a 3:1 internal resonance between two successive transversal vibration modes. Multiple time scale method is applied to the analytical model of the planar extensible-shearable beam with associated boundary conditions, and a second order a...
Article
We present an efficient data-driven sparse identification of dynamical systems. The work aims at reconstructing the different sets of governing equations and identifying discontinuity surfaces in hybrid systems when the number of discontinuities is known a priori. In a two-stages approach, we first locate the switches between separate vector fields...
Article
This work is concerned with a mechanical model of a sympodial tree with first-level branches, which has been shown to exhibit certain properties potentially suitable for biomimetic applications. To investigate these potential benefits further from the viewpoint of the system nonlinear behaviour under external periodic excitation, modern numerical t...
Article
Full-text available
The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of composite material subjected to low-velocity impacts. The structure is assumed to respond in a quasi-static manner and modelled by a continuous beam in large displacement with a lumped mass attached. First, an analytical model was developed to study the...
Conference Paper
We present an efficient data-driven sparse identification of dynamical systems. The work aims at reconstructing the different sets of governing equations and identify discontinuity surfaces in hybrid systems when the number of discontinuities is known a priori. In our approach, we first focus to identify the switches between the separate vector fie...
Article
Full-text available
In this study, we investigate the nonlinear resonant response of a magnetorheological (MR) damper–stay cable system with time delay, and the one-to-one internal resonance is considered. Based on Hamilton’s principle, the motion equations of the MR damper–cable system are derived, and the Galerkin method is applied to obtain the discrete model. Then...
Article
The propagation of periodic flexural waves in an Euler-Bernoulli beam resting on a bilinear elastic foundation is investigated. Although the problem is nonlinear, the closed form solution is obtained thanks to its piecewise linear nature. The dependence of the phase velocity on the two stiffnesses of the substrated is investigated in depth, and it...
Article
Full-text available
A new surgical procedure for the treatment of primary bladder neck obstruction with maintenance of anterograde ejaculation is proposed. In place of monolateral or bilateral bladder neck incision, associated with a loss of ejaculation rate of up to 30%, the new surgical procedure consists of laser drilling the bladder neck with a number of holes and...
Chapter
Several simplified models have been developed for planar nonlinear dynamics of beams based on specific geometrical assumptions and negligibility of some terms. A Timoshenko beam is considered, whose equations of motion up to the third order contain several nonlinear terms. This chapter provides a detailed comparison of the role of nonlinear terms i...
Article
The aim of this research was to investigate the mechanical performance of an earthen massive cladding, recently used for external/internal layers in Platform Frame technology, through an extensive experimental campaign. The masonry is built with extruded unbaked earth blocks and characterized by dovetail horizontally staggered bed joints. The wall...
Article
The paper deals with the experimental and numerical characterization of the in-plane axial and shear mechanical behavior of sprayed in-situ reinforced concrete (RC) sandwich panels, used as structural walls. Axial compression tests were carried out on specimens with different slenderness ratios to study their behavior under axial vertical loads. Wh...
Article
Full-text available
The internal resonances between the longitudinal and transversal oscillations of a forced Timoshenko beam with an axial end spring are studied in depth. In the linear regime, the loci of occurrence of 1 : ir, ir ∈ N ir ∈ N, internal resonances in the parameters space are identified. Then, by means of the multiple time scales method, the 1 : 2 case...
Article
Increasing the signal-to-noise ratio in dynamic atomic force microscopy plays a key role in nanomechanical mapping of materials with atomic resolution. In this work, we develop an experimental procedure for increasing the sensitivity of higher harmonics of an atomic-force-microscope cantilever without modifying the cantilever geometry but instead b...
Article
This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite material without and with lumped mass fixed along its length. The analysis compares the results coming from analytical and numerical modeling with experimental observations. The first part focuses on the analytical model. The model takes into account the n...
Article
The aim of this paper is to present the development of discontinuous approaches to simulate the nonlinear dynamic behaviour of the civic clock tower of Rotella, in the province of Ascoli Piceno (Italy). The study involves the use of the Non-Smooth Contact Dynamics method implemented in the LMGC90© code, where sliding motions are governed by Signori...
Article
Complementing the time-history solution by the frequency-domain analysis can provide a better understanding of micro-structures dynamics. Nevertheless, there exist no research studies in the literature dealing with the dynamics of plate-type MEMS undergoing mechanical shock via the frequency-domain analysis. Therefore, the main object of the presen...
Article
The paper presents the results of an experimental campaign aimed at investigating the in-plane and out of-plane behavior of tuff and fired clay brick masonry panels reinforced by a commercial, not yet tested, Textile Reinforced Mortar (TRM) system. The TRM, consisting of hydraulic lime mortar coupled with a bidirectional glass fabric (total thickne...
Conference Paper
The dynamic behaviour and the seismic vulnerability of different masonry "Apennine Churches", dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to asse...
Conference Paper
The preliminary results of an ambient-vibration based investigation conducted on a large sample of historic masonry towers in the Marche region (Central Italy) are presented, with a focus on the belfry of Collegiata of Santa Maria in Visso (Italy). The assessment procedure includes full-scale ambient vibration testing, ambient modal identification,...
Conference Paper
Italy is a high seismic risk country. Since 1900 more than 30 earthquakes with magnitude greater than Mw=5.8 occurred, and the last one is the Central Italy seismic sequence. The first shock aroused in the 24th August (Mw=6.2) followed by another stronger quake in the 30th October (Mw=6.5). It heavily hit the regions of Marche, Umbria, and Abruzzo...
Article
An analytical solution for the problem of an immersed flexible and vertical heavy rod subjected to a vertical top motion is developed using the multiple scales method directly applied to the partial differential equations of motion. The obtained results show good agreement with a numerical solution obtained using the finite element method for a stu...
Article
Full-text available
Dynamics of a rotor composed of a flexible beam attached to a slewing rigid hub is presented in the paper. Dynamics of the structure is studied for a slender beam model, based on extended Bernoulli-Euler theory, which takes into account a nonlinear curvature, coupled transversal and longitudinal oscillations and non-constant angular velocity of the...
Article
Full-text available
Notwithstanding the presence of some books summarizing specific research bodies on structural systems, reviews on nonlinear dynamics and chaos in mechanical systems and structures are quite few. This paper aims at giving a first contribution in this direction, focusing on chaos in one-dimensional structural mechanics, and reviewing fundamental stud...
Conference Paper
2020 European Association for Structural Dynamics. All rights reserved. In the present paper has been reported the Non-Smooth Contact Dynamics method (NSCD) used for the damage evaluation of the multiple leaf masonry walls of the medieval fortress of Arquata del Tronto, strongly affected by the last Centre Italy earthquakes of August and October 20...
Article
Full-text available
An exact analytical solution for transversal free vibrations of a beam subjected to an arbitrary distributed axial load and a tip tension is obtained by means of a power series representation, whose coefficients are determined recursively in an easy way. The dependence on the natural frequencies on the load is then investigated, and the buckling lo...
Article
In this work, we show that perfectly localised modal vibrations can be obtained in continuous linear elastic structures, provided that, in addition to the regular boundary and continuity/jump conditions, extra (admissibility) conditions are met. They are derived with the aid of: (i) new parameters and/or DOFs of auxiliary systems, and/or (ii) admis...
Article
Full-text available
The dynamic identification of the modal parameters of a structure, in order to gain control of its functionality under operating conditions, is currently under discussion from a scientific and technical point of views. The experimental observations obtained through structural health monitoring (SHM) are a useful calibration reference of numerical m...
Article
Full-text available
In modern engineering applications it is needed to determine the robustness of stable steady states, which depends on the shape and size of the associated basins of attraction. Once the basins are known, the quantitative measures can be computed by means of dynamical integrity tools and arguments. Those numerical techniques applied to strongly nonl...
Article
The internal resonance of a two degree-of-freedom mechanical system with all typical (quadratic and cubic) geometric nonlinearities is studied, limiting to the case of free dynamics. The Multiple Time Scale method is used to provide an analytical, closed form, approximation of the backbone curves. The cornucopia of different possible behaviours tha...
Article
The aim of this research is to investigate, through the Digital Image Correlation (DIC) technique, the mechanical performance of a new type of earth masonry, built with extruded blocks and characterized by dovetail horizontally staggered bed joints. The experimental program consists of two levels of investigations: (i) preliminary phase on componen...
Article
In this work we investigate a model for the description of the impact of a ball with a flexible beam. The coupling of the kinematic parameters of the ball (the velocity components) with the vibration modes of the beam are taken into account by using the Hertz theory of impact. We solve the model equations numerically in a few physically relevant ca...
Article
Full-text available
The aim of this paper is to validate experimentally a nonlinear model of a kinematically excited hinged-simply supported beam with a spring subjected to one end. An experimental setup configuration enables to test different variants of axial boundary conditions: first a typical simply supported beam (no spring), and next two different spring system...
Article
Through a fragility analysis carried out with different probabilistic methods, the vulnerability of an Italian cast-in-place RC industrial structure with precast reinforced hollow brick lightweight vaults is evaluated via nonlinear analyses. After a brief description of the vault construction system, a typical case study built in the 1960s is consi...
Article
Full-text available
The Non-Smooth Contact Dynamics method (NSCD) was selected to investigate the damage occurred to typical masonry churches (namely Apennine Churches) belonging to Central Italy areas affected by the seismic activity started in 2016. The investigated buildings show discontinuous dynamics since the optioned method gave the chance to properly model the...
Article
Full-text available
The problem of flexural wave propagation on a beam resting on an unilateral elastic substrate is addressed. The Euler-Bernoulli beam theory, which is valid for slender beams and for large enough wave length, is used. The governing equations are recalled, and the boundary conditions corresponding to the "single wave" periodic solutions are determine...
Chapter
The paper addresses the nonlinear dynamics of a hinged simply supported beam with an axial elastic support. The investigation is based on the Multiple Time Scales Method (MTSM) applied directly to the governing partial differential equations of motion, and is focused on the first seven bending resonances of a planar system. The effect of axial spri...
Chapter
A geometrically exact beam model is considered along with a total lagrangian finite element approximation. Basic details about kinematics, dynamics and constitutive assumptions on both continuous and discretized models are given. Results of numerical simulations, both in statics and dynamics, are reported and, whenever possible, compared to existin...
Chapter
Analysis of global behaviour of low-dimensional, strongly nonlinear dynamical systems has been well explored in the past, and modern trends are directed toward the investigation of dynamics of systems whose dimension is large, i.e. higher or equal to six. To deal with the huge number of computations required for high-dimensional global analysis, we...
Chapter
In recent years, Italy has been hit by earthquakes, causing significant damage to masonry and reinforced concrete (RC) structures. Especially, common buildings and ordinary structures in many small historical towns of Italian central regions, such as Marche, have suffered dramatic consequences and destruction. Dynamic analysis and seismic structura...
Chapter
We discuss the research that is being carried out at the Department of Civil and Building Engineering and Architecture (Dipartimento di Ingegneria Civile, Edile e Architettura, DICEA) of the Università Politecnica delle Marche (UNIVPM). Over the years the DICEA has steadily focused its attention on resilient environments and buildings, making a gro...
Conference Paper
Full-text available
The seismic vulnerability of school buildings located in the municipality of Trecastelli (Marche, Central Italy) is evaluated with three different numerical models: the lumped plasticity, the distributed plasticity (fibre) and the 3D Continuum FE approaches. Nonlinear static (pushover) analyses are performed to assess the global seismic behaviour o...
Article
The dynamic behaviour and the seismic vulnerability of the ancient civic tower of Amatrice, dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, is studied in this paper by means of advanced 3D numerical analyses with the Non-Smooth Contact Dynamics Method (NSCD). Thus, a discontinuous approach was used to assess...
Conference Paper
The progressive damage of the multiple leaf masonry walls of the Arquata del Tronto medie-val fortress, inside the epicentral zone of the last Centre Italy earthquakes of August and Oc-tober 2016, has been investigated by means of the Non-Smooth Contact Dynamics method (NSCD). According to this model, the masonry structure has been modelled as a sy...
Conference Paper
A dynamic identification technique and the Non-Smooth Contact Dynamics method (NSCD) have been applied to the study of the seismic response of the ancient civic clock tower of Rotella, in the province of Ascoli Piceno, inside the epicentral zone of the last Centre Italy earthquakes of August and October 2016. According to this model, the masonry to...
Article
Full-text available
Background: The vulnerability assessment of existing school buildings against earthquakes represents a priority concern for society. In recent years, several countries promote seismic rehabilitation projects of school buildings, including the allocation of funds to regions with high seismic hazard. Objectives: This research aims to highlight some...
Article
This paper focuses on the analysis of the parametric excitation of a vertical and immersed flexible rod, showing the influence of the choice of the shape function used in the Galerkin’s method. For this, three different reduced-order models (ROMs) are obtained from the continuous equation of transverse motion employing different shape functions. Th...
Article
The preliminary results of an ambient-vibration based investigation conducted on a large sample of historic masonry towers in the Marche region (Central Italy) are presented, with a focus on the belfry of Collegiata of Santa Maria in Visso (Italy). The assessment procedure includes full-scale ambient vibration testing, modal identification from amb...
Article
The use of Textile Reinforced Mortar (TRM) systems represent a valid alternative to traditional strengthening techniques, to improve mechanical strength and seismic performance of masonry buildings. Their effectiveness has been validated by several studies [1-4]. However, the TRM contribution in the mechanical behavior of masonry walls, subjected t...
Article
The dynamic behaviour and the seismic vulnerability of different masonry “Apennine Churches”, dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to asse...
Article
Italy is a high seismic risk country since 1900 more than 30 earthquakes with magnitude greater than M w =5.8 have occurred, and the last one is the Central Italy seismic sequence. The first shock occurred in the 24 August (Mw=6.2) followed by another stronger quake in the 30 th October (Mw=6.5). It hit the regions of Marche, Umbria, and Abruzzo he...
Conference Paper
This study presents a detailed failure analysis of different masonry churches, which were severely damaged during the 2016 Centre of Italy seismic sequence, using nonlinear (i.e., kinematic limit and pushover) analyses. The main aims of the numerical investigations are: (i) to carry out a sufficiently wide sensitivity study on different specific ca...
Conference Paper
The Non-Smooth Contact Dynamics method (NSCD) has been applied to the study of the seismic response of different belfries inside the epicentral zone of the last Centre Italy earth-quakes of August and October 2016. According to this model, the masonry towers have been modelled as a system of rigid blocks, and since the contacts between blocks are g...
Article
Climate change and the raising number of extreme events, such as severe floods, has increased the attention on their effects on urban systems. Urban floods generate important hydrodynamic loads on building and this work proposes a first systematic study on the actions generated by floods with different characteristics (depth, velocity and incidence...
Article
Full-text available
During a seismic improvement intervention that lasted more than one year, a reinforced concrete (RC) school building had been surveyed through dynamic monitoring, granting continuous updates on its global response. Operational Modal Analysis (OMA) was carried out to have a proper understanding of the structure’s dynamic evolution, using a Finite El...
Article
This paper addresses the experimental and numerical characterisation of the structural interface between titanium alloy Ti6Al4V plain bars and Normal (NWC) and Light-Weight Concrete (LWC) mixtures. Results of pull-out tests on ϕ 8 and ϕ 16 mm rebars from NWC and LWC batches and SEM analyses show that, although the employed rebars are plain, the deb...
Chapter
The present chapter highlights the importance of the dynamical integrity theory for micro and nanoapplications. Three case-studies of devices at different scales are presented (a capacitive accelerometer, a microbeam-based micro-electro-mechanical system, and a single-walled slacked carbon nanotube) and different issues commonly addressed in the en...
Chapter
The chapter offers an overview of the effects of the research advancements in nonlinear dynamics on the evaluation of system safety. The achievements developed over the last 30 years entailed a substantial change of perspective. After recalling the outstanding contributions due to Euler and Koiter, we focus on Thompson’s intuition of global safety....