scholarly journals Determination of the drag coefficient of lattice structures under wind load using porous media approach

2021 ◽  
pp. 233-233
Author(s):  
Milada Pezo ◽  
Nikola Mirkov ◽  
Vukman Bakic
Keyword(s):  
Drag Coefficient ◽  
Lattice Structure ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
International Standards ◽  
Lattice Structures ◽  
Three Dimensional Model ◽  
Aerodynamic Forces ◽  
Wind Velocities ◽  
The Stability

The power transmitters, guyed masts and other lattice structures are exposed to wind action. The aerodynamic forces acting on tall tower constructions have crucial importance on the stability of the structure. The lattice structure drag coefficient determination is the subject of the international standards ESDU 81027 and 81028 and Eurocode 3 Part 3.1, but it can also be determined by numerical methods. For that purpose modeling using Computational Fluid Dynamics (CFD) proved to be both accurate and reliable. In this study the fluid flow around the segment of a power transmitter was simulated by a three-dimensional model, where the geometry of the segment is approximated with a porous structure having the appropriate factor of porosity, in order to simplify the geometry. We have used three representative models of turbulence, standard k-? model, RNG k-? model and Reynolds Stress Model. Drag coefficient values are extracted from the flow field and compared for all studied cases and with available experimental results from the wind tunnel. Simulations were performed for four wind velocities between 10 m/s and 30 m/s. The results are supplemented by the ones obtained by Artificial Neural Network. The aim of this study is to show how the simple turbulence model coupled with approximated geometry can be used in the analysis of the aerodynamic forces acting on the lattice structure.

scholarly journals Numerical Analyses on the Stability of a Deep Coalmine Roadway Passing through a Fault Zone: A Case Study of the Gugui Coalfield in China

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2114
Author(s):  
Yongshui Kang ◽  
Congcong Hou ◽  
Jingyi Liu ◽  
Zhi Geng ◽  
Jianben Chen ◽  
...  
Keyword(s):  
Fault Zone ◽  
Distinct Element ◽  
Three Dimensional ◽  
Tectonic Stress ◽  
Three Dimensional Model ◽  
Support Strategy ◽  
Failure Theory ◽  
Calculation Results ◽  
Pass Through ◽  
The Stability

Massive deformation often occurs when deep coalmine roadways pass through a fault zone due to the poor integrity of rock mass and high tectonic stress. To study deformation characteristics of the surrounding rock in the fault zone of a coalmine, a roadway passing through the FD1041 fault zone in China’s Gugui coalfield was investigated in this research. The geo-stress characteristics of this fault zone were analyzed based on the Mohr failure theory. Furthermore, a three-dimensional model for the experimental roadway in the FD1041 fault zone was built and calculated by a numerical program based on the distinct element method. Stability conditions of the roadway, using several types of support methods, were calculated and compared. Calculation results indicated that pre-grouting provides favorable conditions for the stability of a roadway in a fault zone. Finally, an optimized support strategy was proposed and implemented in the experimental roadway. Monitored results demonstrated that the optimized support strategy is appropriate for this fault zone.

scholarly journals Processing Three-Dimensional Models of Archaeological Artifacts

2021 ◽  
Vol 20 (7) ◽  
pp. 48-61
Author(s):  
Pavel V. Chistyakov ◽  
Ekaterina N. Bocharova ◽  
Ksenia A. Kolobova
Keyword(s):  
Three Dimensional ◽  
3D Models ◽  
International Standards ◽  
Post Processing ◽  
Three Dimensional Model ◽  
Scaled Model ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Dimensional Models ◽  
Three Dimensional Models

This article provides a detailed account of the process of scanning, post-processing and further manipulation of three-dimensional models obtained with structured light scanners. Purpose. The purpose of the study is determined by the need for national archaeologists to learn the methods of three-dimensional modeling for the implementation of scientific research corresponding to international standards. Unfortunately, this direction in national archaeology began to develop in a relatively recent time and there is a lag in the application of three-dimensional modeling of national archaeology compared to the world level. Results. Any archaeological, experimental or ethnographic artifact can be used for three-dimensional scanning. To perform post-processing of three-dimensional models it is necessary to carry out primary scanning of an artifact by one of the existing algorithms. The algorithm for creating models, their positioning, simplification, saving in various formats and export is described. The main sequence of 3D models post-processing includes: processing of groups of scanned projections (their cleaning and alignment), creation of artifact model and processing/rectification of the resulting model using special software. Conclusion. As a result of correct implementation of the algorithm, the researcher receives a scaled model completely corresponding to the original artifact. Obtaining a scalable, texture-free three-dimensional model of the artifact, which fully corresponds to the original and exceeds a photograph in the quality of detail transfer, allows a scientist to conduct precise metric measurements and any procedures of non-invasive manipulation of the models. The ability to access a database of three-dimensional models of archaeological collections greatly simplifies the work of archaeologists, especially in situations when country borders are closed.

Green’s function–based surrogate model for windfields using limited samples

2017 ◽  
Vol 42 (3) ◽  
pp. 164-176 ◽  
Author(s):  
Joshua Paul Marshall ◽  
Joseph David Richardson ◽  
Carlos Jose Montalvo
Keyword(s):  
Green’S Function ◽  
Wind Velocity ◽  
Green's Function ◽  
Surrogate Model ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Fast Method ◽  
Three Dimensional Model ◽  
Wind Velocities ◽  
Wind Measurements

There exists many applications for which wind-velocity is desired over a three-dimensional space. The vector field associated with these wind velocities is known as a “windfield” or “velocity-windfield.” The present work provides a fast method to characterize windfields. The approach uses the free-space Green’s function for potential theory as an inexpensive surrogate model in lieu of either complicated physics-based models or other types of surrogate models, both of which require volumetric discretizations for the three-dimensional case. Using the gradient of the third Green’s identity, the wind-velocity in the interior of a domain is entirely characterized by a surface discretization while still providing a three-dimensional model. The unknown densities on the surface are determined from enforcement of the interior form of the identity at arbitrary points coinciding with wind measurements taken by unmanned aerial vehicles. Numerical results support the feasibility of the method.

scholarly journals Safety Evaluation of Underground Caverns Based on Monte Carlo Method

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Qifeng Guo ◽  
Zhihong Dong ◽  
Meifeng Cai ◽  
Fenhua Ren ◽  
Jiliang Pan
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Cumulative Distribution ◽  
Three Dimensional Model ◽  
Maximum Displacement ◽  
The Monte Carlo Method ◽  
Underground Caverns ◽  
The Stability

In order to study the influence of joint fissures and rock parameters with random characteristics on the safety of underground caverns, several parameters affecting the stability of surrounding rock of underground caverns are selected. According to the Monte Carlo method, random numbers satisfying normal distribution characteristics are established. A three-dimensional model of underground caverns with random characteristics is established by discontinuous analysis software 3DEC and excavation simulations are carried out. The maximum displacement at the numerical monitoring points of arch and floor is the safety evaluation index of the cavern. The probability distribution and cumulative distribution function of the displacement at the top arch and floor are obtained, and the safety of a project is evaluated.

An Improved Design of the Manipulator on Automatic Tool Changer

2012 ◽  
Vol 591-593 ◽  
pp. 259-262
Author(s):  
Yan Sheng Li ◽  
Yan Heng Zhang ◽  
Han Xu Sun ◽  
Hai Yang Dong ◽  
Shun Li Zhao
Keyword(s):  
Limit State ◽  
Three Dimensional ◽  
Output Curve ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Automatic Tool Changer ◽  
Automatic Tool ◽  
Improved Design ◽  
The Stability

The tool falling and vibration faults often occur in the process of tool changing, In order to improve the stability of the tools on automatic tool changer, a new structure of the manipulator is presented. The new manipulator contains two-point locking instead of the original one-point locking, and the tools can be clamped more tightly. When the old manipulator is slotting the tool, the forces are analyzed, and the working load and parameters is determined by calculating and analyzing the output curve of manipulator. The three-dimensional model is built in ADMS, and the validity of the new designed manipulator is verified by the simulation in a limit state. The simulation result shows that the new manipulator can increase the ability of tool clamping effectively.

scholarly journals Calibration of a Three-dimensional slope stability evaluation in Brazilian iron open pit mine

2021 ◽  
Author(s):  
Vidal Félix Navarro Torres ◽  
Rodrigo Dockendorff ◽  
Juan Manuel Girao Sotomayor ◽  
Cristian Castro ◽  
Aristotelina Ferreira da Silva
Keyword(s):  
Three Dimensional ◽  
Structural Features ◽  
Open Pit ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Strength Parameters ◽  
Dimensional Section ◽  
The Stability ◽  
Evaluation Techniques

Abstract It has historically been frequent among geotechnical practitioners, that the stability analysis of the slopes of an open pit is performed using a two dimensional section representing the highest and steepest walls within a certain geological setting. However, the literature shows that to predict rupture events in an open pit, a three-dimensional analysis would better represent the actual conditions, as the spatial distribution of the lithology and the structural features play an important role when defining the stability of the slopes. This paper presents the case study of an open it located in Brazil, which experienced instabilities between the years 2001-2019. An evaluation of the behavior of the open pit was performed by calibrating the strength parameters to represent the best documented rupture events. The three-dimensional model was made using the FLAC3D software. The results show that there is a good correlation between the results of the model and the reports of past instabilities. Finally, recommendations are presented for the inter-ramp angles for each lithology based on the calibrated stability analyzes performed. This work seeks to contribute to the knowledge in evaluation techniques for the three-dimensional behavior of open pits.

Mechanical Behaviour of Three Dimensional Lattice Structures

2011 ◽  
Vol 462-463 ◽  
pp. 1302-1307
Author(s):  
Kuniharu Ushijima ◽  
Dai Heng Chen ◽  
Wesley J. Cantwell
Keyword(s):  
Mechanical Behaviour ◽  
Lattice Structure ◽  
Compressive Loading ◽  
Three Dimensional ◽  
Beam Theory ◽  
Lattice Structures ◽  
Initial Stiffness ◽  
Dimensional Lattice ◽  
Collapse Strength ◽  
The One

In this study, a theoretical analysis for predicting the mechanical properties of three dimensional lattice structures under compressive loading is proposed, and verified by comparing the analytical predictions with FEM results. This theory for estimating the initial stiffness E* is based on the classical beam theory, and the one for estimating the plastic collapse strength reflects the stress state for each lattice structure. In particular, effects of inner geometry (strand’s diameter-to-length ratio and micro-architecture) on the mechanical behaviour are discussed.

The Influence of Internal Friction on the Stability of High Speed Rotors With Anisotropic Supports

1969 ◽  
Vol 91 (4) ◽  
pp. 1105-1113 ◽  
Author(s):  
E. J. Gunter ◽  
P. R. Trumpler
Keyword(s):  
Internal Friction ◽  
High Speed ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Analog Computer ◽  
Three Dimensional Model ◽  
Stiffness Properties ◽  
Stiffness Characteristics ◽  
The Stability ◽  
Internal Rotor

This paper evaluates the stability of the single mass rotor with internal friction on damped, anisotropic supports. The paper shows under what conditions the rotor stability may be improved by an undamped support with anisotropic stiffness properties. A three dimensional model is presented to show the influence of rotor and support stiffness characteristics on stability. Curves are also presented on how support damping may also improve or even reduce rotor stability. An analog computer solution of the governing equations of motion is presented showing the shaft transient motion for various speed ranges, and also plots of the rotor steady state motion are given for various speeds up to and including the stability threshold. The analysis is used to explain many of the experimental observations of B. L. Newkirk concerning stability due to internal rotor friction.

Lightweight Design for Hydraulic Support

2010 ◽  
Vol 450 ◽  
pp. 79-82
Author(s):  
Xin Zhang ◽  
Jian Wu Zhang ◽  
Qing Liang Zeng ◽  
Cheng Long Wang
Keyword(s):  
Lightweight Design ◽  
Three Dimensional ◽  
Bottom Plate ◽  
Three Dimensional Model ◽  
Hydraulic Support ◽  
Element Analysis ◽  
Side Plate ◽  
Mining Condition ◽  
The Stability ◽  
Inclined Angle

In large inclined angle mining condition, in order to decrease the effect of sliding force, a lightweight design for hydraulic support is presented in this paper. Taking minimum mass of top beam as optimization objective, the three-dimensional model of it is built firstly. The whole top beam is simplified into top plate, side plate, bottom plate and main reinforcement on the premise of unchanging its topology configuration, and only strength constraint is chosen as constraint, which reduces the number of constraint functions and calculation cycles. By means of ANSYS zero-order optimization module, the mass of top beam is decreased about 16.9%. Finally, the optimal lightweight structure is fully evaluated under the same load as pre-optimization, and finite element analysis results prove that its stress and strain satisfy the need of strength. This lightweight design measure is used in the practical manufacturing with a lower cost of materials, which also increases the stability of hydraulic support in large inclined angle mining condition.

scholarly journals Toward the integration of lattice structure-based topology optimization and additive manufacturing for the design of turbomachinery components

2019 ◽  
Vol 11 (8) ◽  
pp. 168781401985978
Author(s):  
Enrico Boccini ◽  
Rocco Furferi ◽  
Lapo Governi ◽  
Enrico Meli ◽  
Alessandro Ridolfi ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Lattice Structure ◽  
Three Dimensional ◽  
Optimization Method ◽  
Lattice Structures ◽  
Stiffness Properties ◽  
Maximum Stiffness ◽  
Layer Manufacturing ◽  
Innovative Materials

Used in several industrial fields to create innovative designs, topology optimization is a method to design a structure characterized by maximum stiffness properties and reduced weights. By integrating topology optimization with additive layer manufacturing and, at the same time, by using innovative materials such as lattice structures, it is possible to realize complex three-dimensional geometries unthinkable using traditional subtractive techniques. Surprisingly, the extraordinary potential of topology optimization method (especially when coupled with additive manufacturing and lattice structures) has not yet been extensively developed to study rotating machines. Based on the above considerations, the applicability of topology optimization, additive manufacturing, and lattice structures to the fields of turbomachinery and rotordynamics is here explored. Such techniques are applied to a turbine disk to optimize its performance in terms of resonance and mass reduction. The obtained results are quite encouraging since this approach allows improving existing turbomachinery components’ performance when compared with traditional one.

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