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The acoustoelastic effect is basically the correlation between the acoustic properties of a body and his stress state: thus, the study of the acoustoelastic effect is very appealing, since it can be used for determining applied and/or... more
The acoustoelastic effect is basically the correlation between the acoustic properties of a body and his stress state: thus, the study of the acoustoelastic effect is very appealing, since it can be used for determining applied and/or residual stress states, for example starting from the results of ultrasonic tests. A key feature for the effectiveness of this experimental approach is represented by the theoretical model used for describing the influence of the stress on the propagation of acoustic waves. Indeed, standard acoustoelastic experiments have been developed in the context of the so-called third-order elasticity, which requires the use of the apposite acoustoelastic coefficients. Here we adopt a model developed within the linearized elasticity theory for describing the propagation of small amplitude waves in prestressed elastic materials, and consequently for interpreting the acoustoelastic experimental results of ultrasonic tests. In particular, the measured variations of ...
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A bifurcation analysis developed within the context of the nonlinear theory of elasticity usually leads to the study of systems of second-order ODE’s characterized by matrices with varying coefficients. A common practice is that of... more
A bifurcation analysis developed within the context of the nonlinear theory of elasticity usually leads to the study of systems of second-order ODE’s characterized by matrices with varying coefficients. A common practice is that of reducing the governing set of differential equations to a simpler non-autonomous first order linear ODE system. Here, we investigate the potentiality of alternative geometric numerical integrators, based on Lie Group methods, which furnish approximate exponential representations of the matricant of first order linear ODE systems. Within such numerical schemes, the Magnus expansion seems to be very efficient since it features the determination of approximate solutions that preserve at any order of approximation the same qualitative properties of the exact (but unknown) solution and it also exhibits an improved accuracy with respect to other frequently used numerical schemes. As applications of the Magnus method, we study certain paradigmatic bifurcation problems with the major aim of investigating whether solid bodies may support certain instabilities that have common features to some classical hydrodynamic instabilities observed in viscous fluids.
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Abstract The vibration response of a full-scale polycentric near parabolic tuff barrel vault under differential settlements of the abutments are experimentally analyzed. During the experimental tests, the static and dynamic responses of... more
Abstract The vibration response of a full-scale polycentric near parabolic tuff barrel vault under differential settlements of the abutments are experimentally analyzed. During the experimental tests, the static and dynamic responses of the vault have been continuously monitored through a large number of sensors of different kinds placed in suitable points of the structure and supports. The data acquired by the accelerometric sensors are used for detection, localization, and quantitative assessment of the damage by means of a dynamic damage identification (DDI) procedure specifically developed for arches. Numerical models calibrated from experimental results are employed to evaluate the effectiveness of the proposed DDI approach. The position of the crack hinges related to the experimental and theoretical collapse mechanism of the vault, along with their actual depth, turn out to be effectively identified through the proposed DDI procedure, showing the capabilities of such an approach for assessing damage even in existing full-scale masonry constructions.
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Here the lower-bound Theorem of Limit Analysis is applied to historic masonry vaults modeled as continuous no-tension bodies where singular stress fields can take place. To this aim, by following the line traced by Heyman [1], a... more
Here the lower-bound Theorem of Limit Analysis is applied to historic masonry vaults modeled as continuous no-tension bodies where singular stress fields can take place. To this aim, by following the line traced by Heyman [1], a unilateral membrane entirely contained into the thickness of the vault is searched. According to the approach in [2], the problem is reduced to a second order partial differential equation relating the shape function of the membrane and the Airy function associated to the equilibrium stress field. The employ of a suitable numerical procedure together with the formulation of a suitable constrained optimization problem allow us for finding solutions for vaults of general shapes and in presence of arbitrary loads. Moreover, the optimization procedure allows for exploring the entire spectrum of the load bearing capacity of the vault. The effectiveness of the proposed approach is discussed for the representative case of a barrel vault, for which the Geometric Factor of Safety (GFS) under the self-weight and the seismic capacity are studied.
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The problem of the dynamic behavior of masonry arches and vaults has gained increasing interest in recent years, since the key role of these structural elements in the masonry constructions, especially of historic interest. Despite this,... more
The problem of the dynamic behavior of masonry arches and vaults has gained increasing interest in recent years, since the key role of these structural elements in the masonry constructions, especially of historic interest. Despite this, the literature still lacks a sufficiently large number of contributions on this important subject, and this deficiency is even more marked for the case of reinforced masonry. In this context, the present paper shows and discusses some preliminary experimental results on full-scale dynamic tests on unreinforced and GFRCM-reinforced Apulian tuff masonry arches. The experiments have been performed by using a test bench appositely designed and built; the dynamic excitation consisted of a harmonic base motion with fixed amplitude and increasing frequency. The acceleration in suitable points of the arches, the base shear and the base motion have been continuously monitored during the tests.
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Research Interests: Physics and Bifurcation
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Research Interests: Physics and Tensegrity
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A procedure for obtaining a lower bound estimate of the critical load for arbitrary incompressible hyperelastic solids is presented. By considering a lower bound estimate for the Hadamard functional based on the Korn inequality, we... more
A procedure for obtaining a lower bound estimate of the critical load for arbitrary incompressible hyperelastic solids is presented. By considering a lower bound estimate for the Hadamard functional based on the Korn inequality, we establish sufficient conditions for the infinitesimal stability of a distorted configuration. We then determine an optimal lower bound estimate of the critical load in a monotonic loading process and specialize our procedure to the case of homogeneous deformations of incompressible, hyperelastic bodies. We apply our procedure to some representative dead-load boundary value problems for Mooney–Rivlin elastic solids and discuss its effectiveness and handiness for applications by comparing our results to other estimates.
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This work focuses on an experimental and numerical study of a tuff barrel vault first damaged by differential vertical settlements of the abutments without rotations, then reinforced with a FRCM system composed by a fiber-reinforced... more
This work focuses on an experimental and numerical study of a tuff barrel vault first damaged by differential vertical settlements of the abutments without rotations, then reinforced with a FRCM system composed by a fiber-reinforced mortar embedding a basalt fiber net, and finally subjected to a concentrated load on a generatrix (still ongoing). The geometry of the vault (polycentric near parabolic shape) and the masonry material (Apulian tuff) have been chosen in order to be representative of some masonry vaults common in rural constructions of Apulia region; also, a load representative of the infill weight has been applied during all the experimental tests. In parallel to the experiments, numerical simulations by a heterogeneous FE Abaqus model calibrated on the experimentally determined mechanical properties of materials have been performed. This model aims at reproducing the settlement phase and to accurately predict the load bearing capacity of the reinforced structure. To this aim, Concrete Damage Plasticity model has been used for modeling mortar joints and cementitious matrix, whereas tuff bricks have been assumed linearly elastic; finally, the basalt fiber net used in the FRCM reinforced has been described by suitable equivalent elasto-damaging trusses.
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We study the implementation of Stable Unbonded Fiber-Reinforced Elastomeric Isolators (SU-FREI) for the seismic protection of a typical historical masonry construction from Puglia. The effectiveness of this innovative isolation technique... more
We study the implementation of Stable Unbonded Fiber-Reinforced Elastomeric Isolators (SU-FREI) for the seismic protection of a typical historical masonry construction from Puglia. The effectiveness of this innovative isolation technique is analyzed by means of a non-linear dynamic analysis, which shows substantial improvements of the seismic response with respect to the corresponding fixed base construction.
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We show experimental results obtained by an innovative non-destructive approach for the characterization of the damage of composite materials. The analysis regard an aeronautical rotor made of glass fiber–reinforced composite material,... more
We show experimental results obtained by an innovative non-destructive approach for the characterization of the damage of composite materials. The analysis regard an aeronautical rotor made of glass fiber–reinforced composite material, and is developed by applying an ultrasonic immersion C-Scan technique. The experimental data are employed in a damage model developed in the context of the Continuum Damage Mechanics theory. In this model, the evaluation of the damage level depends on a synthetic scalar damage parameter, connected to the quantities directly measured in an ultrasonic test, and related to the specific variation of the acoustical impedance. In particular, from the measurement of the ultrasonic velocity in the undamaged and damaged composite, respectively, we evaluated the damage parameter for an artificially damaged GFRP component.