•We model quasi-static stable crack growth in shape memory alloys (SMAs) under plane strain, mode I loading.•We examine the effect of stress-induced phase transformation on the fracture toughness ...behavior of SMAs.•We examine the sensitivity of the fracture resistance of SMAs to the variation of key thermomechanical parameters.•We discuss the effect of plastic dissipation on the fracture resistance of SMAs.
A finite element analysis is carried out to model quasi-static stable crack growth in shape memory alloys under plane strain, mode I loading. The small scale transformation assumption is employed in the calculations using displacement boundary conditions on a circular region that encloses the stress-induced phase transformation zone. The crack is assumed to propagate in the region of elastically-deformed, fully-transformed martensitic zone ahead of the crack tip with the crack-tip energy release rate maintained at a critical value and the analysis is accomplished using the virtual crack closure technique. Results pertaining to the influence of stress-induced phase transformation on the near-tip mechanical fields and the ratio of the far-field energy release rate to the crack-tip energy release rate are presented, showing fracture toughness enhancement in accordance with experimental observations. Moreover, the effect of plastic dissipation on the fracture resistance of SMAs is discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•A Transfer Matrix Method for infinite multilayered cylinders has been developed.•Interactions with internal and external fluid media are modelled analytically.•Diffuse acoustic field excitation has ...been considered.•The method was validated by comparison with analytical solutions.•The acoustic transmission through heterogeneous cylinders has been predicted.
This paper discusses the use of a Transfer Matrix (TM) method for predicting the acoustic behavior of infinite cylinders consisting of a generic arrangement of homogeneous and heterogeneous periodic layers of various nature (fluid, solid, poroelastic). A through-radius TM is derived for a layer characterized by cylindrical periodicity by manipulating the dynamic stiffness matrix related to a finite element model of a unit cell. The proposed technique is equally appealing for homogeneous layers since few elements are needed in this case. In such a framework, different layers can be combined to form multilayered systems and the related acoustic radiation or transmission due to an external plane wave or a diffuse acoustic field can be assessed. The proposed approach is validated in case of cylinders consisting of homogeneous layers by comparison with alternative approaches. In order to demonstrate the usefulness of the approach, the sound transmission through a cylindrical structure with resonators is presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sound transmission through infinite planar multilayered structures characterized by in-plane periodicity is accurately and efficiently predicted by exploiting free wave propagation and Bloch modes. A ...through-thickness transfer matrix is derived for each layer by manipulating the dynamic stiffness matrix related to a finite element model of a unit cell. The transfer matrices of all the layers composing the structure account for the Bloch modes generated in heterogeneous layers. The proposed technique is equally appealing for in-plane homogeneous structures since few elements and no Bloch modes are needed in this case, ensuring high efficiency. In such a framework, the acoustic radiation or transmission of multilayered systems excited by an oblique plane wave can be assessed. The proposed approach is validated in case of structures consisting of heterogeneous layers by comparison with alternative approaches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A novel approach to investigate and evaluate the damping loss factor of a planar multilayered structure is presented. A statistical analysis reveals the connection between the damping properties of ...the structure and the transmission of sound through the thickness of its laterally infinite counterpart. The obtained expression for the panel loss factor involves all the derivatives of the transmission and reflection coefficients of the layered structure with respect each layer damping. The properties of the fluid for which the sound transmission is evaluated are chosen to fulfil the hypotheses on the basis of the statistical formulation. A transfer matrix approach is used to compute the required transmission and reflection coefficients, making it possible to deal with structures having arbitrary stratifications of different layers and also granting high efficiency in a wide frequency range. Comparison with alternative formulations and measurements demonstrates the effectiveness of the proposed methodology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Sound transmission through infinite planar media characterized by in-plane periodicity is faced by exploiting the free wave propagation on the related unit cells. An appropriate through-thickness ...transfer matrix, relating a proper set of variables describing the acoustic field at the two external surfaces of the medium, is derived by manipulating the dynamic stiffness matrix related to a finite element model of the unit cell. The adoption of finite element models avoids analytical modeling or the simplification on geometry or materials. The obtained matrix is then used in a transfer matrix method context, making it possible to combine the periodic medium with layers of different nature and to treat both hard-wall and semi-infinite fluid termination conditions. A finite sequence of identical sub-layers through the thickness of the medium can be handled within the transfer matrix method, significantly decreasing the computational burden. Transfer matrices obtained by means of the proposed method are compared with analytical or equivalent models, in terms of sound transmission through barriers of different nature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A novel approach to investigate the modal density of a rectangular structure in a wide frequency range is presented. First, the modal density is derived, in the whole frequency range of interest, on ...the basis of sound transmission through the infinite counterpart of the structure; then, it is corrected by means of the low-frequency modal behavior of the structure, taking into account actual size and boundary conditions. A statistical analysis reveals the connection between the modal density of the structure and the transmission of sound through its thickness. A transfer matrix approach is used to compute the required acoustic parameters, making it possible to deal with structures having arbitrary stratifications of different layers. A finite element method is applied on coarse grids to derive the first few eigenfrequencies required to correct the modal density. Both the transfer matrix approach and the coarse grids involved in the finite element analysis grant high efficiency. Comparison with alternative formulations demonstrates the effectiveness of the proposed methodology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The present work describes the use of a transfer matrix method to define the acoustic behavior of multilayered and periodic baffled curved shells consisting of a generic arrangement of homogeneous ...and heterogeneous periodic layers of various nature (fluid, solid, and poroelastic). The dynamic stiffness matrix of a unit cell is manipulated in order to derive the through-radius transfer matrix of a cylindrical periodic layer. Thus, the acoustic radiation or transmission of multilayered shells can be assessed. The blocked pressure field due to an incident plane wave is defined by taking into account the infinite rigid baffle by means of a two-dimensional boundary element model. Analytical expressions for the cylindrical acoustic impedances are utilized to define the coupling with the bounding fluid media. Furthermore, a one-dimensional windowing technique is adopted to account for the finite length of the shells. The proposed approach is validated by systematic comparison with a full finite-boundary element method.
BACKGROUND AND AIMS: Some wineries, in order to promote the growth of yeasts able to ferment grape musts, traditionally produce wines using the ‘pied de cuve’ method. The aim of the present work was ...to study the performance of fortified pied de cuve (FPdC) prepared by addition of wine. METHOD AND RESULTS: Two FPdCs were prepared with the addition of wine at 1.5 and 3% (v/v) of ethanol to the musts and allowed to spontaneously ferment. The FPdCs were then added to fresh bulk musts in order to accelerate the spontaneous alcoholic fermentation (AF). Interestingly, several Saccharomyces cerevisiae strains isolated during the pied de cuve preparation were detected at the highest concentration throughout AF. The chemical composition of the wines conformed to commercial regulations. The volatile organic compounds (VOCs) were mainly represented by diethyl succinate and ethyl lactate, as well as by hexanol and isoamyl alcohol. Principal component analysis of the chemical parameters, VOCs and sensory data showed that the use of experimental pied de cuve influenced positively the composition of the final wines. CONCLUSION: The FPdC had no negative impact on the microbiological and chemical composition of wines, but it affected the diversity of the species S. cerevisiae present during AF and the sensory profile of the final wine. SIGNIFICANCE OF THE STUDY: This study provided evidence that FPdC accelerates spontaneous AF and influences the sensory profile of red wines.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Since 2018, a scientific research project, the “Lilybaeum Project”, is being carried out by a collaboration of physicists and archaeologists. The goal is to apply forefront analysis techniques to the ...investigation of archaeological artefacts, both in situ and in the laboratory. The first case study presented in this paper concerns the original investigation through X-ray computed tomography of a collection of objects from the Regional Archaeological Museum of Lilybaeum, in Marsala, Italy. In addition to a very significant collection of clay jars mostly from children’s graves of the ancient Lilybaeum necropolis, an unprecedented analysis of wooden planks belonging to the only existing wreck of a Punic Ship kept in the Museum is presented.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The effect of thermomechanically induced phase transformation on the driving force for crack growth in polycrystalline shape memory alloys is analyzed in an infinite center-cracked plate subjected to ...a thermal actuation cycle under mechanical load in plain strain. Finite element calculations are carried out to determine the mechanical fields near the static crack and the crack-tip energy release rate using the virtual crack closure technique. A substantial increase of the energy release rate – an order of magnitude for some material systems – is observed during the thermal cycle due to the stress redistribution induced by large scale phase transformation. Thus, phase transformation occurring due to thermal variations under mechanical load may result in crack growth if the crack-tip energy release rate reaches a material specific critical value.
•The effect of thermal actuation on the driving force for crack growth in SMAs is analyzed.•The crack-tip energy release rate is identified as the driving force for crack growth.•Cooling under constant load results in a substantial increase of the energy release rate.•Thermal actuation under constant load may result in crack growth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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