scholarly journals Study on Evolutionary Characteristics of Toppling Deformation of Anti-Dip Bank Slope Based on Energy Field

2020 ◽  
Vol 12 (18) ◽  
pp. 7544
Author(s):  
Liangfu Xie ◽  
Qingyang Zhu ◽  
Yongjun Qin ◽  
Jianhu Wang ◽  
Jiangu Qian
Keyword(s):  
Numerical Model ◽  
Kinetic Energy ◽  
Fracture Surface ◽  
Shear Deformation ◽  
Strain Energy ◽  
Energy Field ◽  
Bank Slope ◽  
Shallow Layer ◽  
Friction Energy ◽  
Toppling Deformation

The evolution of toppling deformation of anti-dip slope is essentially a process of energy dissipation and transformation. Aiming to study the characteristics of energy evolution in different stages, the DEM (discrete element method) software PFC (Particle Flow Code) was utilized to establish a two-dimensional numerical model for a bank slope in Chongqing based on geological background data and field investigation. The DEM model was proven to be reliable not only because the deformation discrepancy between the numerical model and actual bank slope was not large but also because some obvious fractures in the actual bank slope can readily be found in the numerical model as well. In this article, content about displacement in the shallow layer was analyzed briefly. Special effort was made to analyze the energy field and divide the toppling deformation process into three stages. (1) Shear deformation stage: this is an energy accumulating stage in which the strain energy, friction energy, and kinetic energy are all small and the deformation is mainly shear deformation in the slope toe. (2) Stage of main toppling fracture surface hole-through: all three kinds of energy present the increasing trend. The shear deformation in the slope toe expands further, and the toppling deformation also appears in the middle and rear parts of the bank slope. (3) Stage of secondary toppling and fracture surface development: strain energy and friction energy increase steadily but kinetic energy remains constant. Deformation consists mainly of secondary shearing and a fracture surface in the shallow layer. Secondary toppling and fracture surface develop densely.

Numerical simulation and experiment of medium flow energy field in vibrating mill

2018 ◽  
Vol 09 (02) ◽  
pp. 1850011
Author(s):  
Xiaolan Yang ◽  
Yuting Wang ◽  
Zhengqing Xia ◽  
Ting Zhang ◽  
Jifeng Liu
Keyword(s):  
Numerical Simulation ◽  
Kinetic Energy ◽  
Large Amplitude ◽  
Strain Energy ◽  
Low Frequency ◽  
Energy Utilization ◽  
Particle Flow Code ◽  
Energy Field ◽  
Ultrafine Grinding ◽  
Medium Flow

In order to solve to the technical bottleneck that powder is easy to reunite and without refining in the vibration ultrafine grinding (UFG) technology, the energy field of medium flow was studied by analyzing crushing energy and energy transfer. The numerical simulation model of medium flow based on Particle Flow Code (PFC) was established. By setting four kinds of working conditions of amplitude and frequency, the dynamic graphics and curves of the energy field (such as kinetic energy, strain energy, velocity field, force chain and so on) were obtained. In the situation of mid-frequency with large amplitude, the average speed of front medium flow was 1.3–5.03 times that of others and the low-energy region was decreased by 6% to 10%. The largest kinetic energy and strain energy were 3.25 and 2.94 times the average value of others, respectively. The diamond UFG was analyzed in new vibration mills under the conditions of low frequency with large amplitude and mid-frequency with large amplitude. Utilizing a laser particle size analyzer, it was discovered that the particle sizes d(50) in these two models were 3.840[Formula: see text][Formula: see text]m and 0.260[Formula: see text][Formula: see text]m and bandwidths were 9.940[Formula: see text][Formula: see text]m and 3.825[Formula: see text][Formula: see text]m. This highlights the effect of mid-frequency with large amplitude in particle refining and bandwidth narrowing, which is of great importance in the fields of ultra-hard particle refining research and energy utilization.

scholarly journals Mathematical models of supersonic and intersonic crack propagation in linear elastodynamics

2021 ◽  
Author(s):  
Javier Bonet ◽  
Antonio J. Gil
Keyword(s):  
Kinetic Energy ◽  
Crack Propagation ◽  
Mathematical Models ◽  
Linear Elasticity ◽  
Strain Energy ◽  
Equations Of Motion ◽  
Two Dimensions ◽  
Discontinuous Solutions ◽  
Linear Elasticity Theory ◽  
Intersonic Crack Propagation

AbstractThis paper presents mathematical models of supersonic and intersonic crack propagation exhibiting Mach type of shock wave patterns that closely resemble the growing body of experimental and computational evidence reported in recent years. The models are developed in the form of weak discontinuous solutions of the equations of motion for isotropic linear elasticity in two dimensions. Instead of the classical second order elastodynamics equations in terms of the displacement field, equivalent first order equations in terms of the evolution of velocity and displacement gradient fields are used together with their associated jump conditions across solution discontinuities. The paper postulates supersonic and intersonic steady-state crack propagation solutions consisting of regions of constant deformation and velocity separated by pressure and shear shock waves converging at the crack tip and obtains the necessary requirements for their existence. It shows that such mathematical solutions exist for significant ranges of material properties both in plane stress and plane strain. Both mode I and mode II fracture configurations are considered. In line with the linear elasticity theory used, the solutions obtained satisfy exact energy conservation, which implies that strain energy in the unfractured material is converted in its entirety into kinetic energy as the crack propagates. This neglects dissipation phenomena both in the material and in the creation of the new crack surface. This leads to the conclusion that fast crack propagation beyond the classical limit of the Rayleigh wave speed is a phenomenon dominated by the transfer of strain energy into kinetic energy rather than by the transfer into surface energy, which is the basis of Griffiths theory.

A Self-Deployment Hexapod Model for a Space Application

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
G. Aridon ◽  
A. Al Majid ◽  
L. Blanchard ◽  
D. Rémond ◽  
R. Dufour
Keyword(s):  
Numerical Model ◽  
Dynamic Model ◽  
Strain Energy ◽  
The Self ◽  
Hysteretic Behavior ◽  
Simulation Tool ◽  
Space Application ◽  
Tensor Representation ◽  
Restoring Force ◽  
The Impact

This paper presents a simulation tool for predicting the self-deployment of an on-board deployable hexapod based on the release of strain energy stored in six tape-spring actuators. Their hysteretic behavior is described by six restoring force models, and a formulation of a direct dynamic model developed with a Lagrangian approach is performed. Furthermore, tensor representation is used to condense and simplify the calculation of Lagrangian partial derivatives. The results are compared with a numerical model that implements the recursive Newton–Euler technique. Finally, the impact of base excitations on the hexapod deployment performances is evaluated by using the proposed restoring force models.

Modeling of three-dimensional beam nonlinear vibrations generalizing Hencky’s ideas

2022 ◽  
pp. 108128652110679
Author(s):  
Emilio Turco
Keyword(s):  
Kinetic Energy ◽  
Strain Energy ◽  
Nonlinear Vibrations ◽  
Three Dimensional ◽  
Integration Scheme ◽  
Beam Model ◽  
Model Formulation ◽  
Discrete Approach ◽  
Numerical Integration Scheme ◽  
Proposed Model

In this contribution, a novel nonlinear micropolar beam model suitable for metamaterials design in a dynamics framework is presented and discussed. The beam model is formulated following a completely discrete approach and it is fully defined by its Lagrangian, i.e., by the kinetic energy and by the potential of conservative forces. Differently from Hencky’s seminal work, which considers only flexibility to compute the buckling load for rectilinear and planar Euler–Bernoulli beams, the proposed model is fully three-dimensional and considers both the extensional and shear deformability contributions to the strain energy and translational and rotational kinetic energy terms. After having introduced the model formulation, some simulations obtained with a numerical integration scheme are presented to show the capabilities of the proposed beam model.

Effects of Shear Deformation of Struts in Hexagonal Lattices on their Effective In-Plane Material Properties

2021 ◽  
Vol 1034 ◽  
pp. 193-198
Author(s):  
Pana Suttakul ◽  
Thongchai Fongsamootr ◽  
Duy Vo ◽  
Pruettha Nanakorn
Keyword(s):  
Shear Deformation ◽  
Material Properties ◽  
Strain Energy ◽  
Equivalent Strain ◽  
Homogenization Method ◽  
Two Dimensional ◽  
Engineering Applications ◽  
Large Numbers ◽  
Effective Material Properties ◽  
Unit Cells

Two-dimensional lattices are widely used in many engineering applications. If 2D lattices have large numbers of unit cells, they can be accurately modeled as 2D homogeneous solids having effective material properties. When the slenderness ratios of struts in these 2D lattices are low, the effects of shear deformation on the values of the effective material properties can be significant. This study aims to investigate the effects of shear deformation on the effective material properties of 2D lattices with hexagonal unit cells, by using the homogenization method based on equivalent strain energy. Several topologies of hexagonal unit cells and several slenderness ratios of struts are considered. The effects of struts’ shear deformation on the effective material properties are examined by comparing the results of the present study, in which shear deformation is neglected, with those from the literature, in which shear deformation is included.

scholarly journals Numerical Investigation of a Wood-Chip Downdraft Gasifier

2019 ◽  
Vol 113 ◽  
pp. 01002
Author(s):  
Alessandro Vulpio ◽  
Nicola Casari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Alessio Suman
Keyword(s):  
Numerical Model ◽  
Test Bench ◽  
Wood Chip ◽  
Biomass Gasification ◽  
Careful Analysis ◽  
Good Match ◽  
Energy Field ◽  
Downdraft Gasifier ◽  
Virtual Test ◽  
Working Parameters

Biomass gasification is regarded as one of the most promising technology in the renewable energy field. The outcome of such operation, i.e. the synfuel, can be exploited in several ways, for example powering engines and turbines, and is considered more flexible than the biomass itself. For this reason, a careful analysis of the gasification performance is of paramount importance for the optimization of the process. One of the techniques that can be used for such a purpose, is the numerical analysis. CFD is indeed a tool that can be of great help in the design and study of the operation of the gasifier, allowing for an accurate prediction of the operating parameters. In this work, a downdraft gasifier is considered, and the biomass is made of wood chip. The present analysis is devoted to build the numerical model and simulate all the reactions that happen inside an actual gasifier, considering the drying of the wood chip, heating, pyrolysis, and combustion. Good match with experimental results is found, making the numerical model here presented a reliable virtual test bench where investigating the effects of variation in the working parameters.

Study on Hydraulic Characteristics and Optimization of Siphon Channel with Two Inlets in Drydock

2014 ◽  
Vol 638-640 ◽  
pp. 1285-1292
Author(s):  
Peng Zhao ◽  
Yu Chuan Bai
Keyword(s):  
Energy Dissipation ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Dissipation Rate ◽  
Three Dimensional ◽  
Flow State ◽  
Hydraulic Characteristics ◽  
Channel System ◽  
Guide Wall ◽  
Low Efficiency

Compared with the siphon channel with one inlet, the siphon channel with two inlets has some problems such as low efficiency of flooding. Combining with the model test of siphon channel with two inlets in a drydock, three-dimensional numerical model was built to study the hydraulic characteristics of siphon channel system. The reliability of numerical model was confirmed by comparing the calculated value and measured value of hump pressure and flooding rate. Results of turbulent kinetic energy and dissipation rate indicate that flow kinetic energy is mainly dissipated by the friction and its impacting the wall behind partition and the effect of energy dissipation pillars are not obvious. By comparing flow state in front of energy dissipation section and flooding rate between design scheme and modified scheme, it is suggested that the guide wall should be dismantled to ameliorate flow state.

The Rockburst Experiment Usage of Similar Material and the Mechanism of the Energy Releasing

2011 ◽  
Vol 295-297 ◽  
pp. 378-382 ◽  
Author(s):  
Jie Li ◽  
Yue Hong Qian ◽  
Da Peng Li
Keyword(s):  
Kinetic Energy ◽  
Strain Energy ◽  
Peak Velocity ◽  
Hydrostatic Stress ◽  
Similar Material ◽  
Simulation Test ◽  
Underground Engineering ◽  
Recovery Strain ◽  
High Geostress ◽  
Unloading Time

As one of the geological disasters, rockburst is often generated in underground engineering under excavation unloading conditions in high geostress areas. Taking advantage of the simulation test especially for the rock mass under high hydrostatic stress, the dynamic failure rockburst style resulted from instantaneous unloading in one direction was studied, whose peak velocity and acting time are analyzed. The results indicate that the formula for calculating peak velocity and the kinetic energy is proper and the kinetic energy is little portion of the recovery strain energy, most of which is dissipation in different ways; the unloading time at different positions apart from the free surface is nearly the same and more larger than the unloading wave’s disturbance time.

scholarly journals On Dynamic Extension of a Local Material Symmetry Group for Micropolar Media

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1632
Author(s):  
Victor A. Eremeyev ◽  
Violetta Konopińska-Zmysłowska
Keyword(s):  
Energy Density ◽  
Kinetic Energy ◽  
Symmetry Group ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Constitutive Relations ◽  
Kinetic Energy Density ◽  
Material Symmetry ◽  
Local Material ◽  
Micropolar Media

For micropolar media we present a new definition of the local material symmetry group considering invariant properties of the both kinetic energy and strain energy density under changes of a reference placement. Unlike simple (Cauchy) materials, micropolar media can be characterized through two kinematically independent fields, that are translation vector and orthogonal microrotation tensor. In other words, in micropolar continua we have six degrees of freedom (DOF) that are three DOFs for translations and three DOFs for rotations. So the corresponding kinetic energy density nontrivially depends on linear and angular velocity. Here we define the local material symmetry group as a set of ordered triples of tensors which keep both kinetic energy density and strain energy density unchanged during the related change of a reference placement. The triples were obtained using transformation rules of strain measures and microinertia tensors under replacement of a reference placement. From the physical point of view, the local material symmetry group consists of such density-preserving transformations of a reference placement, that cannot be experimentally detected. So the constitutive relations become invariant under such transformations. Knowing a priori a material’s symmetry, one can establish a simplified form of constitutive relations. In particular, the number of independent arguments in constitutive relations could be significantly reduced.

Numerical Simulation of the Added Mass of the Fluid Adjacent to the Ship Hull in Vibration Measured During Sea-Trials in Tanker Ships to be Converted to Offshore Construction Vessel

2012 ◽  
Author(s):  
Severino Fonseca Silva Neto ◽  
Silvia Ramscheid Figueiredo ◽  
Marta Cecilia Tapia Reyes ◽  
Luiza de Mesquita Ortiz
Keyword(s):  
Numerical Model ◽  
Kinetic Energy ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Added Mass ◽  
Vertical Vibration ◽  
Full Scale ◽  
Experimental Results ◽  
Vibration Velocity ◽  
Main Engine

This study aims to analyze the influence of the kinetic energy of the fluid adjacent to the hull of a tanker ship in its vertical vibration frequencies, comparing them with experimental measurements obtained during sea-trials. The one-dimensional modeling of ships allows the construction of simple finite element models from the structural elements of its master section, with structural and added masses, and their frequencies are verified by full-scale measurements, during the sea-trials. The numerical results of these models, with the value of the effective shear area as a fraction of the total area of the strength steel are compared to those obtained in full-scale measurements during sea trials of an oil tanker to be converted to Offshore Construction Vessel. Global vibration measurements were carried out in two of the six ships with the same hull. Accelerometers were installed in eleven strategic points of each hull. Vibration data acquisition was performed simultaneously for these locals in thirteen rotations of the main engine. The amplitude spectra of vibration velocity on the frequency range of measurements were obtained and were plotted graphs of the evolution of the main harmonics, depending on the rotation of the main engine, in order to identify four natural frequencies of the overall vibration of the hull, which were compared to the numerical model. The calculation is performed by the added mass formulations from Burrill, Todd, Kumay and Lewis/Landweber [8] curves, including in all three-dimensional effect by Townsin [17] coefficients, which is checked against the experimental results. The comparison between numerical and experimental results allows assessing the influence of the kinetic energy of the fluid surrounding the hull in the natural frequencies of vibration of the numerical model of the tanker ship and simulating their dynamic behavior after conversion in Offshore Construction Vessel.

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