INSTABILITIES OF INITIALLY STRESSED HYPERELASTIC CYLINDRICAL MEMBRANE AND SHELL UNDER INTERNAL PRESSURE

Summary This paper investigates the static non-linear behaviour and possible instabilities of cylindrical membranes and shells. A detailed experimental analysis was carried out. The structure was analysed using appropriate membrane or shell finite elements and the resulting non-linear equilibrium equations solved using the FE software ABAQUS. A detailed parametric numerical analysis was carried out and the influence of different types of local imperfections was also studied in detail

Effect of Cracks on the Vibration and Bending Behavior of Steel and Aluminum Bars using Finite Element Analysis

Complex structures can develop cracks and defects over time, which can compromise their long-term performance and safety. Structural Health Monitoring (SHM) systems are essential for detecting and measuring these defects by monitoring the load and deformation of the solid materials. This paper presents a simulation study of the frequency and strength of solid cylindrical bars made of aluminum and steel under different loads and crack conditions. Finite Element Method (FEM) and COMSOL Multiphysics software are used to perform the simulation, and a resonance model is used to analyze the results. The study investigates how cracks affect the frequency and deformation of the bars, and how different materials respond to load and bending. The results show that frequency varies linearly with load, cracks decrease the stiffness and increase the frequency at the crack location, and aluminum bars deform more than steel bars. The paper concludes that steel bars are more resistant to load and bending than aluminum bars for both cracked and uncracked case. Finally, it is found that steel bars are more resistant to load and bending than aluminum bars for both cracked and uncracked case

The effects of a visco-elastic polymer glove on hand-arm vibration, muscle activity, and comfort during simulated power tool use

Prolonged exposure to hand-transmitted vibration (HTV) as a result of power tools can lead to hand-arm vibration syndrome (HAVS). The effectiveness of anti-vibration (AV) gloves for the reduction of hand arm vibration remains unclear. The ability of a glove to attenuate vibration is largely influenced by the material properties and forearm muscle activity during tool use. Visco-elastic polymer (gel-based) and air-bladder AV gloves are the most common options, however the material properties of gel based options have seen little attention. The purpose of this study is to investigate vibration transmissibility, forearm muscle activity and subjective grip dexterity using a variety of gel-based compositions and designs. Participants completed six simulated hand-held power tool tasks. RMS vibration, grip force, muscle activity, and perceived levels of comfort, dexterity, onset of forearm muscle fatigue and impairment of tactile sensation were collected. Vibration attenuation was most effective along the Z axis, with properties such as decreased contact stiffness, as well as increased mass, elasticity and viscosity performing better. Further investigation of visco-elastic polymers using the ISO standardized protocol is needed

Coutume de Ferrette et/ou coutume du comté de Belfort

La superposition de la coutume de Ferrette sur celle du comté de Belfort est remise en cause à la fois par un acte de notoriété mais également dans l’analyse de la pratique notariale. Ainsi les usages belfortains protègent davantage les épouses qui ne sont soumises à la répartition inégalitaire (un tiers/deux tiers) qu’à la hauteur de leurs biens acquis pendant la communauté. De plus, la proximité de la Bourgogne permet à la coutume belfortaine permissive, d’évoluer vers l’égalité entre les époux pour le partage final de ces acquêts. Par ailleurs, concernant les apports respectifs, contrairement à la coutume de Ferrette, très défavorable à l’épouse et qui ne favorise guère la dotation de cette dernière, la jeune épousée du comté de Belfort est également dotée par rapport à son futur époux. Mais, il se pose cependant la différence essentielle entre l’égalité de valeur et l’égalité de nature.The status of the customary law of Ferrette prevailing on that of the Comté de Belfort is being questioned both by an affidavit and the study of notarial practices in the Belfort legislation which offer a more extensive protection to wives who, as a matter of fact, are submitted to a very unfair allotment (1/3 2/3) only for their joint estate. Moreover, being close to Bourgogne, Belfort’s customary law would tend towards equality concerning the spouses’ joint estate. As for the spouses’ contribution, contrary to the Ferrette customary law – which was not much in favour of the wife – the customary law of Belfort places the latter on an equal footing with her husband. Still, the question of the difference between equality of contribution and equality of gender subsists.Die Überlagerung des Gewohnheitsrechts der Grafschaft Belfort durch das von Ferette wird in Frage gestellt. Zum einen durch einen urkundlich vollstreckbaren Akt, zum anderen durch eine Analyse der Praxis der Notare. Das Ergebnis : Das Gewohnheitsrecht von Belfort ist günstiger für die Ehefrauen. Ungleich  (ein Drittel/zwei Drittel) wird nur der Teil ihres Vermögens aufgeteilt, der während des gemeinschaftlichen Lebens erworben worden ist. Darüber hinaus gibt die Nähe zu Burgund dem freizügigen Gewohnheitsrecht von Belfort Spielraum, sich, was die endgültigen Aufteilung des Zugewinns betrifft, in Richtung der Parität zu entwickeln.     Außerdem ist die junge Ehefrau in Bezug auf ihre Einbringung  nach dem Gewohnheitsrecht von Belfort genauso dotiert wie ihr künftiger Ehemann. Das Gewohnheitsrecht von Ferette dagegen benachteiligt die Ehefrau in starkem Maße, von ihrer eigenen Dotation erhält sie nur geringfügig mehr als vom Zugewinn. Dennoch, Gleichheit der  Vermögen heißt nicht Gleichheit der Geschlechter, auf diesen grundlegenden Unterschied hat das Gewohnheitsrecht keinen Einfluß

Coutume de Ferrette et/ou coutume du comté de Belfort

La superposition de la coutume de Ferrette sur celle du comté de Belfort est remise en cause à la fois par un acte de notoriété mais également dans l’analyse de la pratique notariale. Ainsi les usages belfortains protègent davantage les épouses qui ne sont soumises à la répartition inégalitaire (un tiers/deux tiers) qu’à la hauteur de leurs biens acquis pendant la communauté. De plus, la proximité de la Bourgogne permet à la coutume belfortaine permissive, d’évoluer vers l’égalité entre les époux pour le partage final de ces acquêts. Par ailleurs, concernant les apports respectifs, contrairement à la coutume de Ferrette, très défavorable à l’épouse et qui ne favorise guère la dotation de cette dernière, la jeune épousée du comté de Belfort est également dotée par rapport à son futur époux. Mais, il se pose cependant la différence essentielle entre l’égalité de valeur et l’égalité de nature.The status of the customary law of Ferrette prevailing on that of the Comté de Belfort is being questioned both by an affidavit and the study of notarial practices in the Belfort legislation which offer a more extensive protection to wives who, as a matter of fact, are submitted to a very unfair allotment (1/3 2/3) only for their joint estate. Moreover, being close to Bourgogne, Belfort’s customary law would tend towards equality concerning the spouses’ joint estate. As for the spouses’ contribution, contrary to the Ferrette customary law – which was not much in favour of the wife – the customary law of Belfort places the latter on an equal footing with her husband. Still, the question of the difference between equality of contribution and equality of gender subsists.Die Überlagerung des Gewohnheitsrechts der Grafschaft Belfort durch das von Ferette wird in Frage gestellt. Zum einen durch einen urkundlich vollstreckbaren Akt, zum anderen durch eine Analyse der Praxis der Notare. Das Ergebnis : Das Gewohnheitsrecht von Belfort ist günstiger für die Ehefrauen. Ungleich  (ein Drittel/zwei Drittel) wird nur der Teil ihres Vermögens aufgeteilt, der während des gemeinschaftlichen Lebens erworben worden ist. Darüber hinaus gibt die Nähe zu Burgund dem freizügigen Gewohnheitsrecht von Belfort Spielraum, sich, was die endgültigen Aufteilung des Zugewinns betrifft, in Richtung der Parität zu entwickeln.     Außerdem ist die junge Ehefrau in Bezug auf ihre Einbringung  nach dem Gewohnheitsrecht von Belfort genauso dotiert wie ihr künftiger Ehemann. Das Gewohnheitsrecht von Ferette dagegen benachteiligt die Ehefrau in starkem Maße, von ihrer eigenen Dotation erhält sie nur geringfügig mehr als vom Zugewinn. Dennoch, Gleichheit der  Vermögen heißt nicht Gleichheit der Geschlechter, auf diesen grundlegenden Unterschied hat das Gewohnheitsrecht keinen Einfluß

Long-Wave Infrared Digital Holography

peer reviewe

Extremum principles for biological continuous bodies undergoing volumetric and surface growth

The volumetric and surface growth of continuum solid bodies is considered, in the framework of the thermodynamics of open systems exchanging mass, work and chemical species (nutrients) with their environment. More specifically, we address the issue of setting up extremum principles for such growing bodies. A general three-field variational principle is set up, based on the so-called zero potential, which is a byproduct of the grand potential. The stationnarity conditions of those potentials deliver balance laws for generalized volumetric and surface Eshelby tensors, leading further to the identification of the material forces for growth

Distribution based model for the grain boundaries in polycrystalline plasticity

This contribution focuses on the development of constitutive models for the grain boundary region between two crystals, relying on the dislocation based polycrystalline model documented in (Evers, L.P., Parks, D.M., Brekelmans, W.A.M., Geers, M.G.D., 2002. Crystal plasticity model with enhanced hardening by geometrically necessary dislocation accumulation. J. Mech. Phys. Solids 50, 2403–2424; Evers, L.P., Brekelmans, W.A.M., Geers, M.G.D., 2004a. Non-local crystal plasticity model with intrinsic SSD and GND effects. J. Mech. Phys. Solids 52, 2379–2401; Evers, L.P., Brekelmans, W.A.M., Geers, M.G.D., 2004b. Scale dependent crystal plasticity framework with dislocation density and grain boundary effects. Int. J. Solids Struct. 41, 5209–5230). The grain boundary is first viewed as a geometrical surface endowed with its own fields, which are treated here as distributions from a mathematical point of view. Regular and singular dislocation tensors are introduced, defining the grain equilibrium, both in the grain core and at the boundary of both grains. Balance equations for the grain core and grain boundary are derived, that involve the dislocation density distribution tensor, in both its regular and singular contributions. The driving force for the motion of the geometrically necessary dislocations is identified from the pull-back to the lattice configuration of the quasi-static balance of momentum, that reveals the duality between the stress and the curl of the elastic gradient. Criteria that govern the flow of mobile geometrically necessary dislocations (GNDs) through the grain boundary are next elaborated on these bases. Specifically, the sign of the projection of a lattice microtraction on the glide velocity defines a necessary condition for the transmission of incoming GNDs, thereby rendering the set of active slip systems for the glide of outgoing dislocations. Viewing the grain boundary as adjacent bands in each grain with a constant GND density in each, the driving force for the grain boundary slip is further expressed in terms of the GND densities and the differently oriented slip systems in each grain. A semi-analytical solution is developed in the case of symmetrical slip in a bicrystal under plane strain conditions. It is shown that the transmission of plastic slip occurs when the angle made by the slip direction relative to the grain boundary normal is less than a critical value, depending on the ratio of the GND densities and the orientation of the transmitted dislocations