As foreseen by Richard Feynman in his famous talk titled There's Plenty of Room at the Bottom in 1959, scientists nowadays are miniaturizing structures in materials to achieve better performance as concerned in technical applications. Reducing grain sizes in polycrystalline materials into the range of less than 100nm, for example, could achieve extraordinary high strength in these so called nan...

When viscous fluid in a corner is disturbed, eddies can form the absence of inertia. Examples flow configurations which this motion occurs include through an abrupt contraction and over cavity. Six decades ago, Moffatt ( J. Fluid Mech. , vol. 18, 1964, pp. 1–18) calculated slow Newtonian fluids sharp corners, detailing his eponymous ‘Moffatt eddies’. In study we examine flows viscoplastic mater...

Available online 12 September 2016 The thermostructural response of the cooling channel of a regeneratively cooled thrust chamber employed for rocket applications can be evaluated by means of analytical and numerical methods. The heat fluxes produced by the combustion inside the thrust chamber cause elevated temperatures in the copper structure composed of ligaments separating the coolant flow ...

NASA has identified the Stirling power converter as a prime candidate for the next generation power system for space applications requiring 60,000 hours of operation. To meet this long-term goal, several critical components of the power converter were analyzed using advanced structural assessment methods. Perhaps the most critical component, because of its geometric complexity and operating env...

Local damage models are known to produce pathological mesh dependence in finite element simulations. The solution is to either use a regularization technique or to adopt a non-local damage model. Viscoplasticity is one technique which can regularize the mesh dependence of local damage model by incorporating a physical phenomenon in the constitutive model i.e. rate effects. A detailed numerical ...

Ahstraet-Simple shearing deformations of a viscoplastic block made of nonpolar and dipolar materials, and placed in a hard loading device are studied. Multiple defects in the block are modeled by perturbing the uniform temperature within the block when the material just starts deforming plastically to that given by a cosine function which assumes relative maximum values at several points in the...

The viscoplastic behavior of high density polyethylene, polypropylene, and polycarbonate under uniaxial tensile loading at constant strain rate and large strains was studied. Standard ASTM samples of the polymers cast by injection molding were tested at room temperature and constant crosshead speed; testing was conducted in the range of 5 to 300 mm/min. A single constitutive relation which capt...

In this dataset, 15 samples of laponite-CMC mixes were realized and their viscoplastic properties are determined. Rheological parameters are then expressed as a function of age and components concentrations.