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We present a study of smart growth in layered cylindrical structures. We start from the characterization of a compatible growth field in an anisotropic growing tube with the aim to show a small perturbation in the compatible growth field that may produce a controlled deprivation of compatibility and localization of elastic energy storage in a composite structure made up of anisotropic growing tubes.

This paper introduces a model for the mechanical response of anisotropic soft materials undergoing large inelastic deformations. The material is considered made by a isotropic matrix with embedded fibers, each component having its own relaxation dynamics. The constitutive equations are provided in terms of the free energy density and the dissipation density, which are both required to be thermodynamically consistent and structural frame-indifferent, i.e., independent of a rotation overimposed on the intermediate natural state of both matrix and fibers. This is in contrast to many of the currently used anisotropic inelastic models, which do not deal with the lack of uniqueness of the intermediate state. This issue is thoroughly discussed and in terms of two possible choices satisfying structural-frame indifference and leading to different flow rules of the inelastic processes. It is shown that different models from the literature can be incorporated in the proposed formulation including anisotropic viscoelasticity and growth.

The paper presents the evolution and trends in the Master’s-level studies in aerospace engineering in Italy, looking at the past 20 years. In the year 2000, a major reform of the higher education in engineering took place in Italy, with the introduction of the so-called ‘Bologna system’ and the clear separation of Bachelor’s and Master’s degree studies. With this reform, a relatively high flexibility was given to universities to define their programme structures. The ministerial rules defined only broad subject areas within which courses and credits should be allocated. This reform allowed the diversification of the educational profile within each university and, even more relevant, allowed the creation of mobility across the country between Bachelor’s and Master’s study programmes. The paper will show the basic facts and figures in the six Italian universities participating in the Partnership of a European Group of Aeronautics and Space UniversitieS (PEGASUS) network (Politecnico di Milano, Politecnico di Torino, Università di Pisa, Università degli Studi di Napoli ‘Federico II’, Sapienza Università di Roma and Alma Mater Studiorum – Università di Bologna), elaborating on the impact of the potential workforce for the sector. Data have been collected from the official open data repository of the Italian Ministry of University, supplemented by information provided by the six universities under analysis. The comparative analysis shows two major results: the positive impact of the reform on the overall Italian higher education and, specifically, a greater appreciation of the aerospace curricula proposed in accordance with the new system.

The study aims to highlight the differences between growth-by-diffusion, based on the elastic stretch of the polymeric network, and growth-by-activity, based on the remodeling of the network, in polymer gels. The study is based on a multiphysics continuum model, which allows to describe the interactions between mechanics, diffusion and growth through a system of nonlinear partial differential equations. We discuss the differences between growth-by-diffusion and growth-by-activity and evidence the role of the corresponding characteristic times in the case of homogeneous activation source. We also show as a huge variety of three-dimensional shapes can be generated by controlling the distribution of the activation sources.

Active elastic instabilities are common phenomena in the natural world, where they have the character of sudden mechanical morphings. Frequently, the driving force of the instability mechanisms has a chemo-mechanical nature, which makes the instabilities very different from the standard elastic instabilities. In this paper, we describe and study the active elastic instability occurring in a swollen spherical closed shell, confining a water-filled cavity, during a dehydration process. We set up a few numerical experiments based on a stress-diffusion model to give an insight into the phenomenon. Then, we present a study that looks at the chemo-mechanical problem and, through a few simplifying assumptions, allows us to derive a semi-analytical model of the phenomenon. It takes into account both the stress state and the water concentration in the walls of the shell at the onset of the instability. Moreover, it considers the invariance of the cavity volume at the onset of instability, which is due to the impossibility of instantaneously changing the cavity volume filled with water. Eventually, it is shown that the semi-analytic model matches very well the outcomes of the numerical experiments far from the initial regime; the ranges of validity of the approximated analytical model are also discussed.

Left ventricle and left atrium are and have been practically always analyzed separately in common clinically and non-clinically oriented cardiovascular investigations. Both classic and speckle tracking echocardiographic data contributed to the knowledge about deformational impairments occurring in systo-diastolic differences. Recently new trajectory based approaches allowed a greater awareness about the entire left ventricle or left atrium revolution and on their deficiencies that take place in presence of hypertrophic cardiomyopathy. However, surprisingly, the concomitant function of the two left heart chambers has not been analyzed for their geometrical/mechanical relationship. For the first time we study here, by acquiring left ventricle and left atrial geometries on the same heartbeat, the trajectory attributes of the entire left heart treated as a whole shape and the shape covariation of its two subunits. We contrasted healthy subjects with patients affected by hypertrophic cardiomyopathy. We found impaired left heart trajectory mainly in terms of orientation and size. More importantly, we found profound differences in the direction of morphological covariation of left ventricle and left atrium. These findings open to new perspectives in pathophysiological evaluation of different diseases by allowing the appreciation of concomitant functioning of both left heart whole geometry and of its two chambers.

International audience; We investigate the morphing of bilayer naturally curved beams and cylindrical shells due to oil extraction from the outer layers. We fabricate bilayer naturally curved beams and cylindrical shells made of PDMS/(PDMS + silicone oil), use the experimental results to validate an explicit formula delivering the change in curvature of the beams, based on the modeling of oil extraction as a bulk contraction. We show as the same model, set up within a 3D context, delivers the morphing of bilayer cylindrical shells and identify potentially interesting results for designing future experiments. In particular, we show as stable states corresponding to the original cylindrical shells can be got in the form of saddle-like shells and cylindrical shells with the axes of principal curvatures switched with respect to the original axes.

Dynamics of solvent release from polymer gels with small solvent-filled cavities is investigated starting from a thermodynamically consistent and enriched multiphysics stress-diffusion model. Indeed, the modeling also accounts for a new global volumetric constraint which makes the volume of the solvent in the cavity and the cavity volume equal at all times. This induces a characteristic suction effect into the model through a negative pressure acting on the cavity walls. The problem is solved for gel-based spherical microcapsules and microtubules. The implementation of the mathematical model into a finite element code allows to quantitatively describe and compare the dynamics of solvent release from full spheres, hollow spheres, and tubules in terms of a few key quantities such as stress states and amount of released solvent under the same external conditions.

The function of left atrium (LA) is closely related to LA remodeling and one of the most important mechanisms is an increased deposition of fibrous tissue that often is the basis for LA electro-mechanical changes before the onset of atrial fibrillation (AF). This study evaluated LA shape and function, by investigating standard and novel strain parameters calculated by a new approach based on homologous times derived from 3D speckle tracking echocardiography (3DSTE) in hypertensive (HT) and paroxysmal atrial fibrillation (PAF) patients with or without left ventricular hypertrophy (LVH), compared to control (C) subjects. LA function was assessed using homologous times to compare strain variables among different individuals, acquired at different physiological time periods. Standard global longitudinal (GLS) and circumferential (GCS) strains were measured at peak of atrial diastole, while longitudinal and circumferential strains (GLSh, GCSh), strain rate (GLSr, GCSr), volume (Vh) and volume rate (Vr) were measured during the atrial telediastolic phase (fifth homologous time) and atrial pre-active phase (tenth homologous time). Using ANOVA, we found an impaired LA deformation detected by standard, interpolated strains and strain rates in both HT and PAF groups compared to C. We also performed ROC analysis to identify different performances of each parameter to discriminate groups (GLSr10 + GCSr10: C vs PAF 0.935; C vs PAF_LVH 0.924; C vs HT_LVH 0.844; C vs HT 0.756). Our study showed anatomical and functional LA remodeling in patients with PAF and HT. 3D strains and strain rates derived from the homologous times approach provide more functional information with improved performance to identify among the explored groups, in particular PAF patients.

In active gels, liquid redistribution, network deformation and material remodeling due to bulk activation, mimicking the presence of molecular motors, are strongly coupled. We present a consistent mathematical model capable to gain a deep understanding of the phenomenon in both steady and transient conditions. With explicit reference to active gel spheres, we evidence the role that not uniform bulk activation may have in generating local stress or strain actuators based on liquid redistribution.

A classical problem in structural mechanics is the evaluation of beam stretching and curvature in slender bilayered beams, due to mechanical actions, thermal distortions, differential growth, and more recently, to swelling. We investigate the non-monotonic changes in the curvature of swollen bilayer beams due to mismatches in physical properties of the two layers starting from a simple structural approach, and discuss the apparent contrast with the well-known Timoshenko’s formula through a scaling analysis. Due to the large strains involved in the problem, we also discuss the problem through a thermodynamics based on Gent model for the elastic contribution to the free-energy of the gels.

One of the main theoretical issues in developing a theory of anisotropic viscoelastic media at finite strains lies in the proper definition of the material symmetry group and its evolution with time. In this paper the matter is discussed thoroughly and addressed by introducing a novel anisotropic remodelling equation compatible with the principle of structural frame indifference, a requirement that every inelastic theory based on the multiplicative decomposition of the deformation gradient must obey to. The evolution laws of the dissipative process are %obtained by introducing a novel (remodelling) balance equation which is completely determined by two scalar functions, the elastic strain energy and the dissipation densities. The proper choice of the dissipation function allows us to reduce the proposed model to the Ericksen anisotropic fluid, when deformation is sufficiently slow, or to the anisotropic hyperelastic solid for fast deformations. Finally, a few prototype examples are discussed to highlight the role of the relaxation times in the constitutive response., Comment: 43 pages,, 9 figures

We introduce a continuum model for a fibre reinforced material in which the reference orientation of the fibre may evolve with time, under the influence of external stimuli. The model is formulated in the framework of large strain hyperelasticity and the kinematics of the continuum is described by both a position vector and by a remodelling tensor which, in the present context, is an orthogonal tensor representing the fibre reorientation process. By imposing suitable thermodynamical restrictions on the constitutive equation, we obtain an evolution equation of the remodelling tensor governed by the Eshelby torque, whose stationary solutions are studied in absence of any external source terms. It is shown that the fibres reorient themselves in a configuration that minimises the elastic energy and get aligned along a direction that may or may not be of principal strain. The explicit analysis of the Hessian of the strain energy density allows us to discriminate among the stationary solutions, which ones are stable. Examples are given for passive reorientation processes driven by applied strains or external boundary tractions. % Applications of the proposed theory to biological tissues, nematic or magneto-electro active elastomers are foreseen., 23 pages, 4 figures

New findings What is the central question of this study? Can impaired deformational indicators for genotype positive for hypertrophic cardiomyopathy in subjects that do not exhibit a left-ventricular wall hypertrophy condition (G+LVH-) be determined using non-invasive 3D echocardiography? What is the main finding and its importance? Using 3D-STE and modern shape analysis, peculiar deformational impairments can be detected in G+LVH- subjects that can be classified with good accuracy. Moreover, the patterns of impairment are located mainly on the apical region in agreement with other evidence coming from previous biomechanical investigations. Abstract We propose a non-invasive procedure for predicting genotype positive for hypertrophic cardiomyopathy (HCM) in subjects that do not exhibit a left-ventricular wall hypertrophy condition (G+LVH-); the procedure is based on the enhanced analysis of medical imaging from 3D speckle tracking echocardiography (3D-STE). 3D-STE, due to its low quality images, has not been used so far to detect effectively the G+LVH- condition. Here, we post-processed echocardiographic images exploiting the tools of modern shape analysis, and we studied the motion of the left ventricle (LV) during an entire cycle. We enrolled 82 controls, 21 HCM patients and 11 G+LVH- subjects. We followed two steps: (i) we selected the most impaired regions of the LV by analysing its strains; and (ii) we used shape analysis on these regions to classify the subjects. The G+LVH- subjects showed different trajectories and deformational attributes. We found high classification performance in terms of area under the receiver operating characteristic curve (∼90), sensitivity (∼78) and specificity (∼79). Our results showed that (i) G+LVH- subjects present important deformational impairments relative to healthy controls and (ii) modern shape analysis can efficiently predict genotype by means of a non-invasive and inexpensive technique such as 3D-STE.

We investigated the stress response of hydrogels to multiple and consecutive planar extensions using the standard Flory–Rehner thermodynamics. We show explicitly how the stress relaxation at a given extension depends on both the number and magnitude of incremental steps that lead to such extension. These results have the potential to impact the design of hydrogel-based actuators where a prescribed extension can be achieved through several consecutive extensions.

In a previous contribution, a new Riemannian shape space, named TPS space, was introduced to perform statistics on shape data. This space was endowed with a Riemannian metric and a flat connection, with torsion, compatible with the given metric. This connection allows the definition of a Parallel Transport of the deformation compatible with the three-fold decomposition in spherical, deviatoric, and non-affine components. Such a parallel transport also conserves the Γ-energy, strictly related to the total elastic strain energy stored by the body in the original deformation. A new approach is here presented in order to calculate the bending energy on the body alone (body bending energy) and to restrict it exclusively within physical boundaries of objects involved in the deformation analysis. The novelty of this new procedure resides in the fact that we propose a new metric to be preserved during the TPS direct transport. This allows transporting the shape change more coherently with the mechanical meaning of the deformation. The geometry of the TPS space is then further discussed in order to better represent the relationship between the Γ-energy, the strain energy, and the so-called bending energy densities.

Nafion membranes, are polymeric thin films widely employed in micro-batteries and fuel cells. These devices are expected to play a key role in the next generation energy systems for use in vehicles as a replacement to combustion engines. In fact, a minimum environmental impact is guaranteed by reduced carbon dioxide emissions. It is usually complicated to investigate the behavior of thin membranes through experiments. Therefore, numerical simulations are carried out in order to enable a better understanding of the phenomena and of the multi-field couplings occurring in polymeric membranes. A continuum-based, three-dimensional and electro-chemo-mechanical (ECM) model for a hydrated polymer membrane is presented. Different effects are taken into account: (i) mechanics, (ii) water uptake, (iii) ion transport, and (iv) electrostatics. The dissipation inequality drives the choice of the suitable constitutive equations of the multi-physics theory. In the mechanical field, an additive decomposition of the deformation gradient in (i) a distortion part, related to the ion motion, and (ii) an elastic part, is assumed. The multi-field model is numerically solved within the finite element framework. Time-dependent simulations are performed by using the commercial tool COMSOL Multiphysics. Furthermore, two closed form solutions are obtained by using (i) a one-dimensional reduced model and (ii) an approach based on the bar theory with an electro-chemical distortion field.

Statistical Shape Analysis, that includes classic Geometric Morphometrics (GM), is often based on landmarks and frequently used to describe shape and shapes changes in biological studies. In this context changes in shape are typically analyzed separately from changes in size measured, in most cases, with centroid size (CS) [1]. Changes in shape are projected in a common linear space: the tangent space to the consensus and decomposed in affine and non affine components. The non affine component can be in turn de-composed in a series of local deformations (partial warps). This approach relies on the assumption that shapes are limitedly scattered in the shape space. In these conditions the difference between centroid size and m-volume is barely appreciable. In medical image, and in general in soft tissues, bodies can undergo very large deformations, involving also large changes in size strictly coupled with the change in shape from mechanical point of view. The cardiac example, analyzed in the present paper, shows changes in volume that can reach the 60% when comparing systole and diastole, coupled with severe longitudinal, radial and torsional strains. Because ventricle’s volume, together with its pressure, is one of the most important descriptors of the pumping heart function, it is natural considering the size change as volumes change. In fact, when dealing with such large size differences, CS and volume behave differently. In the last years the emerging disciplines of Diffeomorphometry and the related Functional Anatomy apply to replace classic GM through the use of diffeomorphisms, more suitable to describe soft tissues changes [2, 3]. On the other hand, these descriptions are very sophisticated but ignore some synthetic properties of the decomposition of deformation in some significant aspects. The goal of the present work is to show that standard GM tools (landmarks, Thin Plate Spline, and related decomposition of the deformation) can be generalized to better describe the very large deformations of biological tissues, without losing a synthetic description. In particular, the classical decomposition of the tangent space to the shape space in affine and non affine components [4] is enriched to include also the change in size, in such a way to give a complete description of the tangent space to the size-and-shape space. The proposed generalization is formulated by means of a new Riemannian metric describing the change in size as change in volume rather than change in CS. This lead to a redefinition of some aspect of the Kendalls size-and-shape space without abandoning Kendalls original formulation. This new formulation is discussed by analyzing 3D heart ventricular shapes coming from 3D Speckle Tracking Echocardiography. We evaluate the performances of different methods in recognizing Control (healthy) subjects from patients affected by Hypertrophic Cardiomyopathy.

We realize steady curved shapes from homogeneous hydrogel flat structures which are in contact with two environments at different chemical conditions. We numerically investigate the behaviour of beam-like and plate-like structures during the transient state, which realize osmotic pumps. Through numerical experiments, we determine the relationship between the difference in the chemical potentials at the top and bottom of a beam and the curvature of the bent beam as well as the Gaussian curvature of a spherical cap morphed from a flat plate. We also propose an approximate modeling of both the beam and the plate, to evaluate explicitly that relationship and show the good agreement between those formulas and the outcomes of the numerical simulations.

We study the dynamics of the dehydration process of a hydrogel with a cavity filled with water. We identify two transient phases: the first one dominated by an inflatable-balloon deformation mode, and the second by a suction effect, determining highly not homogeneous deformation modes of the hydrogel walls. This last phase triggers negative pressures into the cavity up to the typical values of water cavitation. An analysis of the factors allowing to get cavitation pressure inside the cavity is proposed, to allow for precise tuning of the key geometrical and material parameters. The research that led to the present paper was partially supported by a grant of the group GNFM of INdAM.

A mechanics–based analysis of data from three–dimensional speckle tracking echocardiography is proposed, aimed at investigating deformations in myocardium and at assessing shape and function of distinct strain lines corresponding to the principal strain lines of the cardiac tissue. The analysis is based on the application of a protocol of measurement of the endocardial and epicardial principal strain lines, which was already tested on simulated left ventricles. In contrast with similar studies, it is established that endocardial principal strain lines cannot be identified with any structural fibers, not even along the systolic phase and is suggested that it is due to the capacity of the endocardial surface to contrast the dilation of the left ventricle. A mechanics-based analysis of data from three-dimensional speckle tracking echocardiography is proposed, aimed at investigating deformations in myocardium and at assessing shape and function of distinct strain lines corresponding to the principal strain lines of the cardiac tissue. The analysis is based on the application of a protocol of measurement of the endocardial and epicardial principal strain lines, which was already tested on simulated left ventricles. In contrast with similar studies, it is established that endocardial principal strain lines cannot be identified with any structural fibers, not even along the systolic phase and is suggested that it is due to the capacity of the endocardial surface to contrast the dilation of the left ventricle.

Bio–hybrid system are morphing structures whose shaping can be electrically driven and strongly depends on the geometrical and mechanical characteristics of the system. The estimation of those characteristics which allow for getting target shapes is a great challenge. We present and discuss an approximate model for narrow bio–hybrid strips which works well in plane bending. A generalization towards three–layers bio–hybrid system is presented.

The transient behaviour of extremely soft and soft active polymer gels is investigated through a stress-diffusion model which takes into account the active behaviour of the polymer network when molecular motors are included in the solvent bath. The latter is described as a remodeling of the polymer network. The problem of isotropic contraction induced by a homogeneous distribution of molecular motors is explicitly set up and solved. The results have been compared with experiments and show excellent agreement.

Fibre-reinforced elastomers are a class of elastomeric materials with peculiar mechanical properties. If the fibres are metallic or metallic-coated their orientation can be controlled by applying a magnetic field during the curing phase of the elastomer so to tailor the material anisotropy. Once the elastomer is cured, the application of a magnetic field may be used to control the deformation of the solid. In this paper, we aim at modelling both the pre-curing and post-curing phases within a unifying framework compatible with nonlinear elasticity and growth theory. The coupling between elasticity and magnetic field is obtained by considering a proper form of the free energy density which accounts for the mutual orientation between the magnetic field and the fibres. By considering some asymptotic limits, it is shown that the proposed approach incorporates both the usual magneto-elastic model of solids as well as those models used to study the magnetic reorientation of fibres in viscous solutions.

This paper investigates swelling-induced shaping in bilayer thin plates. Sphere-like and nearly developable shapes are realized and the ability to control a specific shaping, shifting from one shape to another, under anisotropic swelling is investigated. It is shown that reinforcing fibers can be crucial in controlling shaping under swelling and dramatically affect the characteristics of the final shapes.

This paper investigates swelling-induced eversion and flattening in curved bilayer gel beams. An explicit formula is produced to evaluate the change in curvature induced by large swelling deformations. The validity is tested against a fully coupled nonlinear three–dimensional stress-diffusion model. Limit situations for nearly-homogeneous and slightly curved beams are discussed.

Polymer gels are porous fluid-saturated materials which can swell or shrink triggered by various stimuli. The swelling/shrinking-induced deformation can generate large stresses which may lead to the failure of the material. In the present research, a nonlinear stress–diffusion model is employed to investigate the stress and the deformation state arising in hydrated constrained polymer gels when subject to a varying chemical potential. Two different constraint configurations are taken into account: (i) elastic constraint along the thickness direction and (ii) plane elastic constraint. The first step entirely defines a compressed/tensed configuration. From there, an incremental chemo-mechanical analysis is presented. The derived model extends the classical linear poroelastic theory with respect to a prestressed configuration. Finally, the comparison between the analytical results obtained by the proposed model and a particular problem already discussed in literature for a stress-free gel membrane (one-dimensional test case) will highlight the relevance of the derived model.

We investigate the adhesion mechanism between an elastic strip of vinylpolysiloxane bent in a racquet-like shape, and a thick elastomeric substrate with the aim to understand how local swelling modifies adhesion. Using a modified loop–tack adhesion test, we place a droplet of silicone oil in between the two materials, vary the dwell time and measure the force required to separate the two interfaces. The experiments are then compared with an analytical model that describes how the critical peel force is modified as the interfacial surface energy changes over time. Our study reveals that in certain circumstances swelling can enhance adhesion. More specifically, strong adhesion is obtained when most of the droplet is absorbed by the solid. By contrast, when the droplet remains at the interface a small adhesive force is measured.

A joint preliminary study has been performed to elucidate the capability of IPMC-based structures mimicking the behavior of biological systems. The structural deformation in response to an applied voltage is described within a nonlinear physics-based model of IPMC actuators. A characteristic of the model is the varying-along-the-thickness relative permittivity of the IPMCs, which takes into account the highly heterogeneous layers resulting from electrode deposition, where charge redistribution occurs. Preliminary experiments on an IPMC-based medusoid are presented to offer some validation of the modeling approach and provide directions for further studies.

We model cardiac muscle contractions in the framework of finite elasticity with large distortions and couple a mechanical model with reaction–diffusion equations representing electrophysiological activity. Both models are implemented using anisotropic constitutive relations: we use stress–strain relations for fiber-reinforced materials, and anisotropic diffusion tensors for both the membrane potential and calcium ions. The effects of these choices on the electromechanical behavior are presented and discussed.

A new mathematical model is presented to describe both the active and passive mechanics of muscles. In order to account for the active response, a two–layer kinematics that introduces both the visible and rest lengths of the muscle is presented within a rational mechanics framework. The formulation is based on an extended version of the principle of virtual power and the dissipation principle. By using an accurate constitutive description of muscle mobility under activation, details of microscopic processes that lead to muscle contraction are glossed over while macroscopic effects of chemical/electrical stimuli on muscle mechanics are retained. The model predictions are tested with isometric and isotonic experimental data collected from murine extensor digitorum muscle. It is shown that the proposed model captures experimental observations with only three scalar parameters.

Gels are widely employed in smart mechanical devices and biomedical applications. Swelling-induced bending actuation can be obtained by means of a simple bilayer gel beam. We show that this system can also exhibit wrinkling patterns of potential interest for structural morphing and sensing. We study swelling-induced wrinkling at the extrados of a bilayer gel beam with the softer layer on top. The bent configuration at finite strain is recovered first and, starting from it, a linear perturbation analysis is performed. We delimit the zone corresponding to wrinkling modes in a parameter plane encompassing a mechanical stiffness ratio and a geometric top layer to total height ratio. Interestingly, we observe that surface instability precedes and envelopes wrinkling modes of finite wavelength. Finally, we discuss the effect of changes in stiffness and of the Flory–Huggins parameters χ on the size of the wrinkling domain.

The analysis of full Left Atrium (LA) deformation and whole LA deformational trajectory in time has been poorly investigated and, to the best of our knowledge, seldom discussed in patients with Hypertrophic Cardiomyopathy. Therefore, we considered 22 patients with Hypertrophic Cardiomyopathy (HCM) and 46 healthy subjects, investigated them by three–dimensional Speckle Tracking Echocardiography, and studied the derived landmark clouds via Geometric Morphometrics with Parallel Transport. Trajectory shape and trajectory size were different in Controls versus HCM and their classification powers had high AUC (Area Under the Receiving Operator Characteristic Curve) and accuracy. The two trajectories were much different at the transition between LA conduit and booster pump functions. Full shape and deformation analyses with trajectory analysis enabled a straightforward perception of pathophysiological consequences of HCM condition on LA functioning. It might be worthwhile to apply these techniques to look for novel pathophysiological approaches that may better define atrio–ventricular interaction.

The aim of the paper is to solve and discuss the representation problem of a special class of integrable distortion fields in fibred cylindrical bodies and to analyze the corresponding induced shape changes. We find and discuss the compatibility conditions, i.e. the conditions to be satisfied to get a pair compatible distortion/shape change, when different fields of fibers are assigned on the cylindrical body, through the specification of the fields of fiber angles.

The modeling of the complex response of the IPMC-like body to electrical and mechanical stimuli is set within the context of the 3-D theory of linear elasticity. A field of chemically induced distortions is included in the model; these mechanical distortions and the derivation of the final PDE equations of the multiphysics problem are thermodynamically consistent. Some results of the numerical experiments are revisited through an original analysis of the stress distribution along the IPMC-like body.

We present a procedure that detects myocardial infarction by analyzing left ventricular shapes recorded at end-diastole and end-systole, involving both shape and statistical analyses. In the framework of Geometric Morphometrics, we use Generalized Procrustes Analysis, and optionally an Euclidean Parallel Transport, followed by Principal Components Analysis to analyze the shapes. We then test the performances of different classification methods on the dataset. Among the different datasets and classification methods used, we found that the best classification performance is given by the following workflow: full shape epicardium+endocardium analyzed in the Shape Space i.e. by scaling shapes at unit size; successive Parallel Transport centered toward the Grand Mean, in order to detect pure deformations; final statistical analysis via Support Vector Machine with radial basis Gaussian function. Healthy individuals show both a stronger contraction and a shape difference in systole with respect to pathological subjects. Moreover, endocardium clearly presents a larger deformation when contrasted with epicardium. Eventually, the solution for the blind test dataset is given. When using Support Vector Machine for learning from the whole training dataset and for successively classifying the 200 blind test dataset, we obtained 96 subjects classified as normal and 104 classified as pathological. After the disclosure of the blind dataset this resulted in 95i¾?% of total accurracy with sensitivity at 97i¾?% and specificity at 93i¾?%.

We investigate the swelling–induced bending of a gel bilayer beam with homogeneous beam–like components, when the beam is embedded in a solvent bath of assigned chemical potential. We set the problem within the limits of finite elasticity with large distortions, with these latter determined via chemical equilibrium, by the elastic modulus of the gel, the chemical potential of the bath and the solvent–gel interaction parameter. We borrow our method of solution from finite bending of soft and incompressible beams, and get a non dimensional nonlinear equation governing the solution of the problem, whose solution is validated through a campaign of numerical experiments based on a complete stress–diffusion model.

We study volume transition phenomenon in hydrogels within the framework of Flory–Rehner thermodynamic modelling; we show that starting from different models for the Flory parameter different conclusions can be achieved, in terms of admissible coexisting equilibria of the system. In particular, with explicit reference to a one-dimensional problem we establish the ranges of both temperature and traction which allow for the coexistence of a swollen and a shrunk phase. Through consideration of an augmented Flory–Rehner free-energy, which also accounts for the gradient of volume changes, we determine the position of the interface between the coexisting phases, and capture the connection profile between them.