Giovanni Lancioni

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

In this paper, a complete picture of the different plastic failure modes that can be predicted by the strain gradient plasticity model proposed in Del Piero et al. (J. Mech. Mater. Struct. 8:109–151, 2013) is drawn. The evolution problem of the elasto-plastic strain is formulated in Del Piero et al. (J. Mech. Mater. Struct. 8:109–151, 2013) as an i...

Ultra High Performance Fiber Reinforced Concrete (UHPFRC) is an innovative material with great mechanical and durability performances, high ductility and toughness. Although the mechanical behaviour of UHPFRC has been extensively studied in the last years, the damage mechanisms and permanent strains of this material when subjected to flexural loads...

Ultra‐High Performance Fiber‐Reinforced Concrete (UHPFRC) is considered a promising material for many structural applications where high strength and high energy absorption capacity are required. The purpose of this work is to study the uniaxial tensile behavior of soft cast (flowable at casting time) UHPFRC by varying the amount of hooked steel fi...

Composites made of reinforcing short fibers embedded into brittle matrices, like, e.g., fiber-reinforced concretes, exhibit enhanced strength and ductility properties. Their failure process induced by tensile loadings involves hardening and softening stages as a result of matrix multiple micro-cracking, due to stress bridging of fibers across matri...

The use of Fabric Reinforced Cementitious Matrix (FRCM) systems to reinforce existing masonry and concrete structures is nowadays a well-established practice. The mechanical characterization of FRCM systems is of fundamental importance to define the correct parameters needed to design a strengthening intervention. However, some aspects regarding FR...

Damage process in engineering systems is strongly affected by spatial heterogeneity and local discontinuities in the materials, which are significantly influencing the reliability and integrity of the systems. In this paper, we present a new stochastic approach as a tool for performing uncertainty quantification in simulating damage evolution in he...

In this chapter, two different strain gradient plasticity models based on nonconvex plastic energies are presented and compared through analytical estimates and numerical experiments. The models are formulated in the simple one-dimensional setting, and their ability to reproduce heterogeneous plastic strain processes is analyzed, focusing on strain...

The bond strength at the yarn to matrix interface is one of the key factor affecting the FRCM mechanical behavior. The interaction between multi-filament yarn and cementitious matrix, governed by complex mechanisms, determines the behavior and failure mode of this composite system.

Fiber Reinforced Cementitious Matrix (FRCM) systems have emerged in recent years as an effective tool for strengthening and retrofitting of the existing built heritage. The effectiveness of FRCM systems is strongly related to the bond developed at the interface between inorganic matrix and fabric reinforcement and between the inorganic matrix and t...

The paper reports the results of a blind benchmark developed as a part of the preliminary activity of the research project RiSEM (Italian acronym for Seismic Risk on Monumental Buildings). The benchmark was aimed at comparing the results obtained with different analytical models and/or numerical analysis techniques (variational approach, finite ele...

The use of inorganic cement based composite systems, known as Fiber Reinforced Cementitious Matrix (FRCM), is a very promising technique for retrofitting and strengthening the existing masonry or concrete structures. The effectiveness of FRCM systems is strongly related to the interface bond between inorganic matrix and fabric reinforcement, and, s...

The challenging and innovative idea of realizing a table totally made of fiber-reinforced concrete is explored through an interdisciplinary research activity, where contributions coming from different fields (design, material science, experimental testing, numerical modeling) are combined. The paper describes the different phases of the study, star...

A variational model for the evolution of damage in elastic materials is proposed, which is based on incremental energy minimization. Analytical solutions are determined in the one-dimensional case of a tensile bar, and the issue of their stability is addressed. Analytical results have given insights into the properties that elastic and damage energ...

The use of externally applied composite systems to upgrade, strengthen or rehabilitate masonry or concrete structures is well established. However, structural strengthening with organic type composites, such as fiber-reinforced polymer (FRP) systems, may be impractical when the element is exposed to high-temperature service conditions, due to signi...

A variational model based on incremental energy minimization is proposed to describe the evolution of damage in elastic materials. The model accounts for an elastic energy, depending on the damage variable, and for a damage energy, which has a local and a non-local term. The evolution of the displacement and damage fields, representing the problem...

The dynamics of two Roman stone arches has been studied by means of the Non-Smooth Contact Dynamics method (NSCD), implementing a discrete element numerical model in the LMGC90 code. Schematized as a system of rigid blocks, undergoing frictional sliding and plastic impacts, the arches have exhibited a complex dynamics, because of the geometrical no...

The motion of a windshield wiper blade is modelled by a mass-spring-damper system on a moving frictional surface. The system dynamics is time-varying, since three different regimes of motion, characterized by different degrees of freedom, are possible. Indeed the system, which schematizes a blade cross-section, can experience stick and slip motions...

This paper analyses the effect of the form of the plastic energy potential on the (heterogeneous) distribution of the deformation field in a simple setting where the key physical aspects of the phenomenon could easily be extracted. This phenomenon is addressed through two different (rate-dependent and rate-independent) non-local plasticity models,...

Metal forming processes involve continuous strain path changes inducing plastic anisotropy which could result in the failure of the material. It has been often observed that the formation and evolution of meso-scale dislocation microstructures under monotonic and non-proportional loading have substantial effect on the induced anisotropy. It is ther...

A non-local variational model for the evolution of plastic deformation and fracture in tensile bars is proposed. The model is based on an energy functional, sum of an elastic bulk energy, a non-convex dissipative inelastic energy, and a quadratic non-local gradient term, as in (Del Piero et al. in J. Mech. Mater. Struct. 8(2–4):109–151, 2013). The...

A numerical method is proposed to study the scattering of seismic shear waves induced by the presence of underground cavities in homogeneous soils. The method is based on the superposition of two solutions: the solution of the free-wave propagation problem in a uniform half-space, easily determined analytically, and the solution of the wave scatter...

Plastic deformation induces various types of dislocation microstructures at different length scales, which eventually results in a heterogeneous deformation field in metallic materials. Develop-ment of such structures manifests themselves as macroscopic hardening/softening response and plastic anisotropy during strain path changes, which is often o...

licenses/by-nc-nd/3.0/). Selection and peer-review under responsibility of the Abstract In this paper two different non-local plasticity models are presented and compared to describe the necking and fracture through a non-convex energy, where fracture is regarded as the extreme localization of the plastic strain. The difference between the models a...

The Non-Smooth Contact Dynamics method (NSCD), implemented in the LMGC90 code, has been applied to the study of the seismic response of a medieval church, the S. Maria in Portuno's Church at Corinaldo (AN, Italy). According to this model, the church masonry has been modelled as a system of rigid blocks, whose sliding motions are governed by the Sig...

In the fracture model presented in this paper, the basic assumption is that the energy is the sum of two terms, one elastic and one cohesive, depending on the elastic and inelastic part of the deformation, respectively. Two variants are examined: a local model, and a nonlocal model obtained by adding a gradient term to the cohesive energy. While th...

The dynamics of a medieval church, the S. Maria in Portuno's church, subjected to seismic loadings has been analyzed by using LMGC90, a distinct element code which implements the Non-Smooth Contact dynamics method. Since the contact between blocks is governed by the Signorini's impenetrability condition and the dry-friction Coulomb's law, the churc...

High-order absorbing boundary conditions (ABC) and perfectly matched layers (PML) are two powerful methods to numerically solve wave problems in unbounded domains. The aim of the proposed study is to analyze and compare the performance of these methods in the one-dimensional problem governed by the dispersive wave equation. The PMLs proposed in lit...

In this paper we anticipate some results of a work in progress (Del Piero et al., 2012), in which the phenomena of fracture and yielding are described by a cohesive energy model, and fracture is regarded as a consequence of an extreme localization of the inelastic deformation. We first study a local model, which is successful in describing a number...

High-order absorbing boundary conditions (ABC) and perfectly matched layers (PML) are two powerful methods to numerically solve wave problems in unbounded domains. In the first part of the proposed paper these two techniques are applied to the problem of wave propagation in cables laid on elastic supports, governed by the one-dimensional dispersive...

In this work, we investigate the primary nonlinear resonance response of a one-dimensional continuous system, which can be regarded as a model for semi-infinite cables resting on an elastic substrate reacting in compression only, and subjected to a constant distributed load and to a small harmonic displacement applied to the finite boundary. By int...

A transversely isotropic plate is said incoherent when the transverse isotropy material axis is at an angle with the geometrical axis orthogonal to the plate cross section. In this paper two plate theories for the free-vibration of such plates are formulated. These theories are based on two different representations for the displacement field, both...

This communication anticipates some results of a work in progress [1], addressed to explore the efficiency of the diffuse cohesive energy model for describing the phenomena of fracture and yielding. A first local model is partially successful, but fails to reproduce the strain softening regime. A more robust non-local model, obtained by adding an e...

When a semi-infinite cable resting on a bed of unilateral springs is subjected to a harmonic excitation, the motion of the touch-down-point (TDP), i.e., the point which separates the detached part of the cable from the laid part, and which is assumed to be unique in this paper, exhibits interesting resonant phenomena. These phenomena are studied nu...

The dynamics of a semi-infinite Bernoulli–Euler beam laid on a bed of unilateral elastic springs is governed by a moving-boundary problem, since the positions of the touch-down points, those points which separate the detached beam parts from the laid ones, are unknown. This problem is solved numerically by means of a self-made finite element code a...

Four different variational models of fracture are considered. They are numerically implemented by means of a self-made finite element code and the crack evolution in a fiber-matrix composite body is simulated. The different results are compared.

The performances of three different high order absorbing boundary conditions (ABCs) are investigated in the case of progressive and standing waves in a dispersive one-dimensional medium. Their accuracy is first analyzed with respect to the frequency of a single incident wave. Then they are submitted to a wave train characterized by a wide frequency...

We analyze the dynamics of a two-dimensional system constituted by two masses subjected to elastic, gravitational and viscous forces and constrained by a moving frictional mono-lateral surface. The model exhibits a time-varying dynamics capable of reproducing the hopping phenomenon, an unwanted phenomenon observed in many applications such as the m...

Recently, Francfort and Marigo (J. Mech. Phys. Solids 46, 1319–1342, 1998) have proposed a novel approach to fracture mechanics based upon the global minimization of a Griffith-like functional, composed of a bulk and a surface energy term. Later on the same authors, together with Bourdin, introduced (in J. Mech. Phys. Solids 48, 797–826, 2000) a va...

In the variational model for brittle fracture proposed in Francfort and Marigo [1998. Revisiting brittle fracture as an energy minimization problem. J. Mech. Phys. Solids 46, 1319–1342], the minimum problem is formulated as a free discontinuity problem for the energy functional of a linear elastic body. A family of approximating regularized problem...

The dynamics of a semi-infinite Euler-Bernoulli beam on unilateral elastic springs is investigated. The mechanical model is governed by a moving-boundary hyperbolic problem, which cannot be solved in closed form. Therefore, we look for approximated solutions following two different approaches. From the one side, approximate analytical solutions are...

A two-dimensional dynamic theory is formulated for transversely isotropic plates whose material-symmetry axis slightly deviates from the normal to the plate cross section (this type of transverse isotropy is said to be weakly incoherent). The model is based on a representation of the admissible motions capable of capturing obliqueness in response....

Standard plate theories [6-9] deal with coherent plates, that is to say, plates made of a linearly elastic material which (either is isotropic or) has a preferred response axis c parallel to the normal z to the plate’s cross section: typically, the material is transversely isotropic with respect to c, or monoclinic with respect to a plane nor-mal t...

The near-cutoff propagation of free waves of flexure in a transversely isotropic, linearly electroelastic plate is studied, in two cases: for the simplest kinematics, when both the mechanical displacement and the electric potential are taken linear in the thickness variable; and for the enriched, third-order kinematics. The dispersion curves are fo...

: A finite element model for the nonlinear dynamics of semi-infinite beams on unilateral Winkler soil is proposed. An appropriate boundary condition is used to simulate the infinite length of the beam, and the nonlinearity due to the motion of the touch-down point, which separates the laid part of the beam from the suspended one, is detected by a r...

A variational model for irreversible quasi-static crack evolution in quasi-brittle materials is proposed in which, at each time step, the equilibrium crack paths are associated with stationary points of a particular energy function, composed of bulk and surface energy terms. The approach is similar to that proposed in [4-5] but, here, a substantial...

. In this communication we anticipate some results of the work in progress [1], where a variational model aiming at a unified approach to fracture and plasticity is proposed. The model is based on an energy functional which is the sum of three volume integrals: a reversible elastic energy, a dissipative cohesive energy and a non-local energy depend...