Domain discretizations for numerical solution of fracture problems

2021 ◽  
pp. 45-52
Author(s):  
В.А. Коршунов ◽  
А.В. Мащенко ◽  
Р.С. Мудрик ◽  
Д.А. Пономарев ◽  
А.А. Родионов
Keyword(s):  
Numerical Solution ◽  
Cohesive Zone ◽  
Arbitrary Shape ◽  
Three Dimensional ◽  
Cylindrical Sample ◽  
Fracture Pattern ◽  
Brazilian Test ◽  
Random Shape ◽  
Upper Level ◽  
Good Agreement

В работе для численного моделирования хрупкого разрушения с целью повышения эффективности громоздких расчетов предлагается использовать двухуровневую процедуру построения сетки дискретизации. На верхнем уровне генерируется сетка фрагментов - локусов задаваемых размеров и произвольной случайной формы, по границам которых может происходить разрушение. На нижнем уровне каждый локус разбивается на сетку конечных элементов. Разрыв связей между конечными элементами по траектории разрушение между локусами реализуется с помощью процедуры сцепляющей среды. Для построения сетки дискретизации верхнего уровня использована диаграмма Воронова. Разработан алгоритм процедуры создания локусов на телах произвольной формы в двумерной и трехмерной постановках. Процедура реализована на языке APDL, для использования в программном комплексе ANSYS. Алгоритм протестирован при различных значениях задаваемых параметров и на объектах разнообразной формы. Численное решение задачи о разрушении цилиндрического образца из хрупкого материала по бразильскому тесту определения прочностных характеристик материала на растяжение продемонстрировало хорошее согласование полученной картины разрушения с реальной. In this paper, for numerical modeling of brittle fracture in order to increase the efficiency of complex calculations, it is proposed to use a two-level procedure for generating a discretization network. At the upper level, a network of fragments – locus’s, of specified sizes and arbitrary random shape, is generated. At the lower level, each locus is meshed by FE. The breaking of connections between finite elements along the trajectory of destruction between locus is realized using the cohesive zone procedure. The properties of the Voronov diagram are used to generate the upper-level discretization network. The algorithm of the procedure for creating locus on bodies of arbitrary shape in two-dimensional and three-dimensional formulations is developed. The procedure is implemented in the APDL, for use in the ANSYS. The algorithm is tested at various values of the specified parameters and on objects of various shapes. The numerical solution of the problem of the destruction of a cylindrical sample made of brittle material according to the Brazilian test for determining the tensile strength characteristics of the material demonstrated a good agreement of the obtained fracture pattern with the real one.

Cohesive Zone Modeling for 3D Ductile Crack Propagation

2016 ◽  
Vol 853 ◽  
pp. 132-136 ◽  
Author(s):  
Xiao Li ◽  
Huang Yuan
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Ductile Materials ◽  
Zone Modeling ◽  
Good Agreement

Computational modeling of three-dimensional crack propagation in very ductile materials is still a challenge in fracture mechanics analysis. In the present work a new stress-triaxiality-dependent cohesive zone model (TCZM) is proposed to describe elastic-plastic fracture process in full three-dimensional specimens. The cohesive parameters are identified as a function of the stress triaxiality from ductile fracture experiments. The predictions of TCZM show good agreement with the experimental results for both side-grooved C(T) specimen and rod bar specimen.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals 3D-Volume Rendering of the Pelvis with Emphasis on Paraurethral Structures Based on MRI Scans and Comparisons between 3D Slicer and OsiriX®

2021 ◽  
Vol 45 (3) ◽  
Author(s):  
C. M. Durnea ◽  
S. Siddiqi ◽  
D. Nazarian ◽  
G. Munneke ◽  
P. M. Sedgwick ◽  
...  
Keyword(s):  
Image Processing ◽  
Secondary Analysis ◽  
Three Dimensional ◽  
3D Models ◽  
Clinical Role ◽  
Cross Sectional ◽  
3D Slicer ◽  
Mri Scans ◽  
3D Volume ◽  
Good Agreement

AbstractThe feasibility of rendering three dimensional (3D) pelvic models of vaginal, urethral and paraurethral lesions from 2D MRI has been demonstrated previously. To quantitatively compare 3D models using two different image processing applications: 3D Slicer and OsiriX. Secondary analysis and processing of five MRI scan based image sets from female patients aged 29–43 years old with vaginal or paraurethral lesions. Cross sectional image sets were used to create 3D models of the pelvic structures with 3D Slicer and OsiriX image processing applications. The linear dimensions of the models created using the two different methods were compared using Bland-Altman plots. The comparisons demonstrated good agreement between measurements from the two applications. The two data sets obtained from different image processing methods demonstrated good agreement. Both 3D Slicer and OsiriX can be used interchangeably and produce almost similar results. The clinical role of this investigation modality remains to be further evaluated.

scholarly journals Experimental and Numerical Investigation about Small Clearance Journal Bearings under Static Load Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Carlo Alberto Niccolini Marmont Du Haut Champ ◽  
Fabrizio Stefani ◽  
Paolo Silvestri
Keyword(s):  
Three Dimensional ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Small Scale ◽  
Test Rig ◽  
Small Clearance ◽  
Dimensional Simulation ◽  
Dynamic Loading Conditions ◽  
Static And Dynamic Loading ◽  
Good Agreement

The aim of the present research is to characterize both experimentally and numerically journal bearings with low radial clearances for rotors in small-scale applications (e.g., microgas turbines); their diameter is in the order of ten millimetres, leading to very small dimensional clearances when the typical relative ones (order of 1/1000) are employed; investigating this particular class of journal bearings under static and dynamic loading conditions represents something unexplored. To this goal, a suitable test rig was designed and the performance of its bearings was investigated under steady load. For the sake of comparison, numerical simulations of the lubrication were also performed by means of a simplified model. The original test rig adopted is a commercial rotor kit (RK), but substantial modifications were carried out in order to allow significant measurements. Indeed, the relative radial clearance of RK4 RK bearings is about 2/100, while it is around 1/1000 in industrial bearings. Therefore, the same original RK bearings are employed in this new test rig, but a new shaft was designed to reduce their original clearance. The new custom shaft allows to study bearing behaviour for different clearances, since it is equipped with interchangeable journals. Experimental data obtained by this test rig are then compared with further results of more sophisticated simulations. They were carried out by means of an in-house developed finite element (FEM) code, suitable for thermoelasto-hydrodynamic (TEHD) analysis of journal bearings both in static and dynamic conditions. In this paper, bearing static performances are studied to assess the reliability of the experimental journal location predictions by comparing them with the ones coming from already validated numerical codes. Such comparisons are presented both for large and small clearance bearings of original and modified RKs, respectively. Good agreement is found only for the modified RK equipped with small clearance bearings (relative radial clearance 8/1000), as expected. In comparison with two-dimensional lubrication analysis, three-dimensional simulation improves prediction of journal location and correlation with experimental results.

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