arXiv subjects

Carlo Sansour

Publications and source records attributed to Carlo Sansour.

3 recordsLinked to original sources

arXiv2026

A finite-strain logarithmic viscoelastic model for Antarctic ice shelves based on an additive split

Ice shelves lose mass primarily by calving, a process controlled by the near-front stress field on timescales that span elastic flexure and viscous creep. We formulate a finite-strain Maxwell model for glacier ice in logarithmic strain space. The Hencky strain of a fixed reference configuration is split additively at the level of rates into elastic and viscous parts; the spring is isotropic Hencky elasticity and the dashpot is a Glen-type power law written on the logarithmic strain rate and its work-conjugate stress. At infinitesimal strain the dashpot coincides with Glen's flow law; the elastic strains in the ice-shelf configurations of this paper remain in that regime. The model is integrated with a midpoint evaluation and a backward-Euler correction of the trial dual, and implemented in a finite-element setting. After a viscoelastic column benchmark, the formulation is applied to an idealised ice tongue, including depth-dependent density and moduli, temperature-dependent fluidity, and cliff geometries with a frontal foot or basal undercutting. The resulting stress fields show how viscoelasticity and front morphology control tension near the terminus.

physics.comp-ph↗

arXiv2023

Non-invasive in silico determination of ventricular wall pre-straining and characteristic cavity pressures

The clinical application of patient-specific modelling of the heart can provide valuable insights in supplementing and advancing methods of diagnosis as well as helping to devise the best possible therapeutic approach for each individual pathological heart condition. The potential of computational cardiac mechanics, however, has not yet been fully leveraged due to the heart's complex physiology and limitations in the non-invasive in vivo characterisation of heart properties necessary required for accurate patient-specific modelling such as the heart anatomy in an unloaded state, ventricular pressure, the elastic constitutive parameters and the myocardial muscle fibre orientation distribution. From a solid mechanics point of view without prior knowledge of the unloaded heart configuration and the cavity pressure-volume evolution, in particular, the constitutive parameters cannot be accurately estimated to describe the highly nonlinear elastic material behaviour of myocardial tissue. Here, knowledge of the volume-normalized end-diastolic pressure relation for larger mammals is exploited in combination with a novel iterative inverse parameter optimisation framework to determine end-systolic and end diastolic pressures, ventricular wall pre-straining and pre-stressing due the residual end-systolic cavity pressure as well as myocardial tissue stiffness parameters for biventricular heart models.

physics.med-ph↗

arXiv2021

Local micromorphic non-affine anisotropy for materials incorporating elastically bonded fibers

There has been increasing experimental evidence of non-affine elastic deformation mechanisms in biological soft tissues. These observations call for novel constitutive models which are able to describe the dominant underlying micro-structural kinematics aspects, in particular relative motion characteristics of different phases. This paper proposes a flexible and modular framework based on a micromorphic continuum encompassing matrix and fiber phases. It features in addition to the displacement field so-called director fields which can independently deform and intrinsically carry orientational information. Accordingly, the fibrous constituents can be naturally associated with the micromorphic directors and their non-affine motion within the bulk material can be efficiently captured. Furthermore, constitutive relations can be formulated based on kinematics quantities specifically linked to the material response of the matrix, the fibres and their mutual interactions. Associated stress quantities are naturally derived from a micromorphic variational principle featuring dedicated governing equations for displacement and director fields. This aspect of the framework is crucial for the truly non-affine elastic deformation description. In contrast to conventional micromorphic approaches, any non-local higher-order material behaviour is excluded, thus significantly reducing the number of material parameters to a range typically found in related classical approaches. In the context of biological soft tissue modeling, the potential and applicability of the formulation is studied for a number of academic examples featuring anisotropic fiber-reinforced composite material composition to elucidate the micromorphic material response as compared with the one obtained using a classical continuum mechanics approach.

physics.comp-ph↗