Non-principal surface waves in deformed incompressible materials

The Stroh formalism is applied to the analysis of infinitesimal surface wave propagation in a statically, finitely and homogeneously deformed isotropic half-space. The free surface is assumed to coincide with one of the principal planes of the primary strain, but a propagating surface wave is not restricted to a principal direction. A variant of Taziev’s technique [R.M. Taziev, Dispersion relation for acoustic waves in an anisotropic elastic half-space, Sov. Phys. Acoust. 35 (1989) 535–538] is used to obtain an explicit expression of the secular equation for the surface wave speed, which possesses no restrictions on the form of the strain energy function. Albeit powerful, this method does not produce a unique solution and additional checks are necessary. However, a class of materials is presented for which an exact secular equation for the surface wave speed can be formulated. This class includes the well-known Mooney–Rivlin model. The main results are illustrated with several numerical examples

Application of an experimental design to study AISI 4340 and 300M steels electropolishing in a concentrated perchloric/acetic acid solution

The objective of this study was to assess AISI 4340 and 300 M steels electropolishing performance in aconcentrated perchloric/acetic acid electrolyte. The statistical analysis on a two-level fractional design(FFD)24-1was proposed to define an adequate tool to describe the dissolved thickness and thefinalsurface via arithmetic roughness Ra. A compromise zone was defined for each steel by considering allthe requirements for both responses of each steel: dissolved thickness between 15–17μm andarithmetic roughness criteria less than 0.06μ

In vivo measurement of skin surface strain and sub-surface layer deformation induced by natural tissue stretching.

Stratum corneum and epidermal layers change in terms of thickness and roughness with gender, age and anatomical site. Knowledge of the mechanical and tribological properties of skin associated with these structural changes are needed to aid in the design of exoskeletons, prostheses, orthotics, body mounted sensors used for kinematics measurements and in optimum use of wearable on-body devices. In this case study, optical coherence tomography (OCT) and digital image correlation (DIC) were combined to determine skin surface strain and sub-surface deformation behaviour of the volar forearm due to natural tissue stretching. The thickness of the epidermis together with geometry changes of the dermal-epidermal junction boundary were calculated during change in the arm angle, from flexion (90°) to full extension (180°). This posture change caused an increase in skin surface Lagrange strain, typically by 25% which induced considerable morphological changes in the upper skin layers evidenced by reduction of epidermal layer thickness (20%), flattening of the dermal-epidermal junction undulation (45-50% reduction of flatness being expressed as Ra and Rz roughness profile height change) and reduction of skin surface roughness Ra and Rz (40-50%). The newly developed method, DIC combined with OCT imaging, is a powerful, fast and non-invasive methodology to study structural skin changes in real time and the tissue response provoked by mechanical loading or stretching

Waves and surface stability in preformed hyperelastic solids

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Biomécanique de la peau en vue d'applications dans le domaine lésionnel

Journées scientifiques, GDR MECABIO, AUTRANS, FRANCE, 06-/01/2016 - 06/01/2016Biomécanique de la peau en vue d'applications dans le domaine lésionne

Surface stability of nonlinear magnetoelastic solids

The present paper proposes to identify surface stability when a magnetoelastic half-space is subjected to a pure homogeneous pre-deformation and to a magnetic field normal to its (plane) boundary. Clearly, the aim is to find the critical stretch ratio beyond which surface instabilities may develop, or in other words, to establish a bifurcation criterion based on the incremental static solution of the boundary value problem. We want to analyse how the presence of a coupling between magnetism and nonlinear elasticity modify the conditions of stability.This work was supported by grants from the Minist`ere d´el´egu´e`a la recherche (France), the Minist`ere des Affaires´etrang`eres (France), the University of Glasgow (Scotland), the CNRS (France), and the Royal Society (UK). The authors are also verygrateful to G´erard Maugin for valuable suggestions

Mechanical Properties of Excised Human Skin

CMBEE Valencia 2010Deposited by bulk impor