Search results for "SIMULATION"
showing 10 items of 5095 documents
Gradient-enhanced model and its micromorphic regularization for simulation of Lüders-like bands in shape memory alloys
2018
Abstract Shape memory alloys, notably NiTi, often exhibit softening pseudoelastic response that results in formation and propagation of Luders-like bands upon loading, for instance, in uniaxial tension. A common approach to modelling softening and strain localization is to resort to gradient-enhanced formulations that are capable of restoring well-posedness of the boundary-value problem. This approach is also followed in the present paper by introducing a gradient-enhancement into a simple one-dimensional model of pseudoelasticity. In order to facilitate computational treatment, a micromorphic-type regularization of the gradient-enhanced model is subsequently performed. The formulation empl…
First-principles calculations of iodine-related point defects in CsPbI3
2019
Many thanks to A. Lushchik, A. Popov and R. Merkle for numerous fruitful discussions. This study was partly supported by the Latvian Council for Science (grant LZP-2018/1-0147 to EK). R.A.E acknowledges the assistance of the University Computer Center of Saint-Petersburg State University for high-performance computations.
Three-Dimensional Strain Analysis of Single-Lap Bolted Joints in Thick Composites Using Fibre-Optic Gauges and the Finite-Element Method
2010
Bolted joints involving composite plates used to be almost entirely dedicated to aerospace applications. As the need for energy conservation has increased, the field of composite bolted joints has found new applications in ground armoured vehicles. Thick panels able to withstand large in-plane and impact loads are critical. The present investigation evaluates the interior strain field, through the thickness, of a composite plate connected to an aluminium panel with a single-lap bolted joint. The area of interest is the bearing plane region close to the hole because of the presence of stress concentrations that heavily modify the stress field. Experimental data for the bolted joint were rec…
Spiral wave induced numerically using electrical stimulation and comparison with experimental results.
2010
Experiments in vitro on a Microelectrode Array (MEA) platform show that electrical stimulation can provoke the generation of spiral waves in cardiac tissue. Nevertheless, the conditions leading to this artificial fibrillation state remain unclear. In order to have a better understanding of this phenomenon, a numerical simulation study has been conducted. The results obtained with a two-dimensional FitzHugh-Nagumo model proved that it is possible to create spiral waves by adding a stimulation current under certain conditions, which are made explicit.
Forces and deformations of the abdominal wall—A mechanical and geometrical approach to the linea alba
2011
Force-elongation responses of the human abdominal wall in the linea alba region were determined by tensile tests in which the linea alba was seen to exhibit a nonlinear elastic, anisotropic behavior as is frequently observed in soft biological tissues. In addition, the geometry of the abdominal wall was determined, based on MRI data. The geometry can be specified by principal radii of curvature in longitudinal of approximately 470 mm and in the transverse direction of about 200 mm. The determined radii agree with values found in other studies. Mechanical stresses, deformations and abdominal pressures for load cases above 6% elongation can be related using Laplace's formula and our constitut…
Proteins in amorphous saccharide matrices: Structural and dynamical insights on bioprotection
2013
Bioprotection by sugars, and in particular trehalose peculiarity, is a relevant topic due to the implications in several fields. The underlying mechanisms are not yet clearly elucidated, and remain the focus of current investigations. Here we revisit data obtained at our lab on binary sugar/water and ternary protein/sugar/water systems, in wide ranges of water content and temperature, in the light of the current literature. The data here discussed come from complementary techniques (Infrared Spectroscopy, Molecular Dynamics simulations, Small Angle X-ray Scattering and Calorimetry), which provided a consistent description of the bioprotection by sugars from the atomistic to the macroscopic …
Design of a reactor operating in supercritical water conditions using CFD simulations. Examples of synthesized nanomaterials
2011
International audience; Direct information about fluids under supercritical water conditions is unfeasible due to the engineering restrictions at high pressure and high temperature. Numerical investigations based on computational fluid dynamics (CFD) calculations are widely used in order to get extensive information on the fluid behavior, particularly to help the design of a new reactor. This paper presents the numerical investigations performed on an original supercritical water device, especially in the level of the reactor. CFD calculations allow to design and optimize the present reactor described in this study. Currently, this process produces some nanometric oxide powders in continuou…
Electrical conductance of carbon nanotubes with misaligned ends
2013
During a manufacturing process, when a straight carbon nanotube is placed on a substrate, e.g., production of transistors, its two ends are often misaligned. In this study, we investigate the effects of multiwall carbon nanotubes’ (MWCNTs) outer diameter and chirality on the change in conductance due to misalignment of the two ends. The length of the studied MWCNTs was 120 nm, while the diameters ranged between 4 and 7 nm. A mixed finite element-tight-binding approach was carefully designed to realize reduction in computational time by orders of magnitude in calculating the deformation-induced changes in the electrical transport properties of the nanotubes. Numerical results suggest that ar…
Fatigue crack initiation and subsequent crack growth in fillet welded steel joints
2019
Abstract The fatigue damage evolution in fillet welded steel joints where cracks are emanating from the weld toe is investigated. Based on existing experimental data for as-welded joints including crack depth measurements of the early crack growth it is proposed to make a distinction between the crack initiation phase and the subsequent crack growth phase. The welded detail in question is an F class detail with plate thickness 25 mm made of medium strength carbon steel. It is found that the crack initiation phase defined at a crack depth of 0.1 mm is close to 25% of the fatigue life even at a relatively high constant stress range of 150 MPa. At lower stress ranges it is concluded that the i…
Comparison of the friction and wear properties of titanium and oxidised titanium in dry sliding against sintered high speed steel HS18-0-1 and agains…
2005
Abstract The paper presents the results of conformal pin-on-disc tribological tests concerning the hard oxidised zone, α-Ti(O), created at the surface of a titanium specimens sliding against the sintered and hardened up to 850 HV30, Grade T1 high speed steel (HS18-0-1) counterspecimens. Comparison with the results obtained for the tests performed against hardened up to 620 HV30 C45 carbon steel counterspecimens has been done. Testing was carried out at room temperature and at unlubricated conditions. After tests the structures and compositions of the worn surfaces and wear debris were a subject of LOM, SEM observations and X-ray microanalyses. In comparison with the baseline—the Ti/T1 HSS c…