Smoothed Particle Methods and Their Applicability to Tribology

2011 ◽  
Author(s):  
Jonathan P. Kyle ◽  
Elon J. Terrell
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Hydrodynamic Lubrication ◽  
Particle Methods ◽  
Governing Equations ◽  
Problem Domain ◽  
Numerical Accuracy ◽  
Recent Interest ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

An in-house solver was created to simulate contact mechanics and hydrodynamic lubrication using smoothed particle hydrodynamics (SPH), SPH is a meshfree, particle-based method that can be used to solve continuum problems in solid and fluid mechanics. In this approach, the problem domain is represented by particles that move according to prescribed governing equations. Because smoothed particle methods have been shown to have the advantage of being able to model large deformations without concern of degradation in numerical accuracy, they have received recent interest for application to complex problems in tribology—the exploration of which is the focus of this study.

Application of Smoothed Particle Hydrodynamics to Full-Film Lubrication

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Jonathan P. Kyle ◽  
Elon J. Terrell
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Hydrodynamic Lubrication ◽  
Fluid Velocity ◽  
Lubrication Theory ◽  
Particle Methods ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Computational Fluid Dynamics Cfd ◽  
Film Lubrication

An in-house solver was created in order to simulate hydrodynamic lubrication utilizing smoothed particle hydrodynamics (SPH). SPH is a meshfree, Lagrangian, particle-based method that can be used to solve continuum problems. In this study, transient hydrodynamic lubrication in a pad bearing geometry was modeled utilizing the SPH method. The results were validated by comparison to computational fluid dynamics (CFD) and an analytical solution provided by lubrication theory. Results for the pressure distribution between SPH and CFD were agreeable while lubrication theory failed to capture any inertial effects of the fluid. Velocity profile comparisons differed slightly between all three methods. However, since smoothed particle methods have been shown to have the advantage of being able to model large deformations, as well as allowing easy definitions of fluid-solid interfaces, they can be useful tools for complex problems in tribology.

Modeling Hypervelocity Impacts Using Smoothed Particle Hydrodynamics

2018 ◽  
Author(s):  
M. Ganser ◽  
B. van der Linden ◽  
C. G. Giannopapa
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Hypervelocity Impact ◽  
Density Fluctuations ◽  
Computational Domain ◽  
Simulation Tool ◽  
Hypervelocity Impacts ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

Hypervelocity impacts occur in outer space where debris and micrometeorites with a velocity of 2 km/s endanger spacecraft and satellites. A proper shield design, e.g. a laminated structure, is necessary to increase the protection capabilities. High velocities result in massive damages. The resulting large deformations can hardly be tackled with mesh based discretization methods. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless scheme, can resolve large topological changes whereas it still follows the continuous formulation. Derived by variational principles, SPH is able to capture large density fluctuations associated with hypervelocity impacts correctly. Although the impact region is locally limited, a much bigger domain has to be discretized because of strong outgoing pressure waves. A truncation of the computational domain is preferable to save computational power, but this leads to artificial reflections which influence the real physics. In this paper, hypervelocity impact (HVI) is modelled by means of basic conservation assumptions leading to the Euler equations of fluid dynamics accompanied by the Mie-Grueneisen equation of state. The newly developed simulation tool SPHlab presented in this work utilizes the discretization method smoothed particle hydrodynamics (SPH) to capture large deformations. The model is validated through a number of test cases. Different approaches are presented for non-reflecting boundaries in order to tackle artificial reflections on a computational truncated domain. To simulate an HVI, the leading continuous equations are derived and the simulation tool SPHlab is developed. The method of characteristics allows to define proper boundary fluxes by removing the inwards travelling information. One- and two-dimensional model problems are examined which show excellent absorption behaviour. An hypervelocity impact into a laminated shield is simulated and analysed and a simple damage model is introduced to model a spallation failure mode.

A STABLE LARGE DEFORMATION CORRECTED SPH METHOD BASED ON STABILIZED CONFORMING NODAL INTEGRATION AND LAGRANGIAN KERNELS

2012 ◽  
Vol 09 (04) ◽  
pp. 1250057
Author(s):  
S. WANG
Keyword(s):  
Large Deformation ◽  
Smoothed Particle Hydrodynamics ◽  
Solid Mechanics ◽  
Particle Methods ◽  
Sph Method ◽  
Nodal Integration ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Meshless Approximation ◽  
Complex Phenomena

In this paper, we propose a Galerkin-based smoothed particle hydrodynamics (SPH) formulation with moving least-squares meshless approximation, applied to solid mechanics and large deformation. Our method is truly meshless and based on Lagrangian kernel formulation and stabilized nodal integration. The performance of the methodology proposed is tested through various simulations, demonstrating the attractive ability of particle methods to handle severe distortions and complex phenomena.

scholarly journals Cylindrical Smoothed Particle Hydrodynamics Simulations of Water Entry

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Kai Gong ◽  
Songdong Shao ◽  
Hua Liu ◽  
Pengzhi Lin ◽  
Qinqin Gui
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Three Dimensional ◽  
Water Entry ◽  
Surface Velocity ◽  
Governing Equations ◽  
Pressure Fields ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
Dam Break Flow

This paper presents a smoothed particle hydrodynamics (SPH) modeling technique based on the cylindrical coordinates for axisymmetrical hydrodynamic applications, thus to avoid a full three-dimensional (3D) numerical scheme as required in the Cartesian coordinates. In this model, the governing equations are solved in an axisymmetric form and the SPH approximations are modified into a two-dimensional cylindrical space. The proposed SPH model is first validated by a dam-break flow induced by the collapse of a cylindrical column of water with different water height to semi-base ratios. Then, the model is used to two benchmark water entry problems, i.e., cylindrical disk and circular sphere entry. In both cases, the model results are favorably compared with the experimental data. The convergence of model is demonstrated by comparing with the different particle resolutions. Besides, the accuracy and efficiency of the present cylindrical SPH are also compared with a fully 3D SPH computation. Extensive discussions are made on the water surface, velocity, and pressure fields to demonstrate the robust modeling results of the cylindrical SPH.

Shock Analysis of Underwater Explosion Using Smoothed Particle Hydrodynamics

2004 ◽  
Author(s):  
S. Matsumoto ◽  
S. Itoh
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Underwater Explosion ◽  
Experimental Result ◽  
Governing Equations ◽  
Detonation Products ◽  
Sph Method ◽  
Equation Of States ◽  
Cylindrical Coordinate ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

A blasting process includes large deformations and inhomogeneities caused by shock waves as well as the detonation gases generated by explosives. Smoothed Particle Hydrodynamics (SPH) is a meshless and complete Lagrangian method. The properties of SPH method can overcome the difficulty of a simulation in a blasting process. In this study, the simulation of an underwater explosion using SEP (Safety Explosives) as a cylindrical high explosive is carried out to confirm the advantage of SPH method for the analysis in a blasting process. The Euler equations are used for the governing equations of both water and the detonation products of the explosive. The Jones-Wilkins-Lee (JWL) equation and the Mie-Gru¨neisen equation are used as the equation of states for the detonation products and water, respectively. The two-dimensional and axisymmetrical simulation in cylindrical coordinate system is adopted to analyze the underwater explosion. The simulation result is compared with the experimental result and shows that SPH method can well simulate the underwater explosion.

scholarly journals Particle-based modeling and meshless simulation of flows with Smoothed Particle Hydrodynamics

2019 ◽  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Atomic Scale ◽  
Particle Methods ◽  
Mesh Free ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Mesh Free Methods ◽  
Mesh Grid

<p>Smoothed Particle Hydrodynamics (SPH) is a promising simulation technique in the family of Lagrangian mesh-free methods, especially for flows that undergo large deformations. Particle methods do not require a mesh (grid) for their implementation, in contrast to conventional Computational Fluid Dynamics (CFD) methods. Conventional CFD algorithms have reached a very good level of maturity and the limits of their applicability are now fairly well understood. In this paper we investigate the application of the SPH method in Poiseuille and transient Couette flow along with a free surface flow example. Algorithmically, the method is viewed within the framework of an atomic-scale method, Molecular Dynamics (MD). In this way, we make use of MD codes and computational tools for macroscale systems.</p>

scholarly journals Simulation the deformation and damage of a rock massive containing a cavity

2020 ◽  
pp. 138-145
Author(s):  
Виталий Алексанрович Трофимов ◽  
Иван Евгеньевич Шиповский
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Economic Activity ◽  
Fracture Process ◽  
Strain State ◽  
Fracture Criterion ◽  
Large Deformations ◽  
Karst Formation ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Accumulation Of Damage

Карстовые проявления широко распространены во многих регионах и представляют значительную опасность для проживания и хозяйственной деятельности. Воронки возникают при обрушении горных пород над подземными пустотами (пещерами, выработками и т.д.), образовавшимися при карстовом процессе или в результате антропогенного воздействия в массиве горных пород. Однако не каждая карстовая или техногенная полость приводит к разрушению земной поверхности, и, как правило, ее возникновение является неожиданным. В данной работе рассматривается динамика формирования провалов земной поверхности в виде карстовой воронки. Для этого с помощью бессеточного метода сглаженных частиц (SPH) решается геомеханическая задача. Выбранный численный метод позволяет получить решение задачи с учетом больших деформаций и возможных разрушений в процессе изменения напряженно-деформированного состояния. Используется критерий разрушения Друккера-Прагера, параметры которого со временем меняются в соответствии с накоплением повреждений, которые определяют временное развитие процесса разрушения, его начало и скорость. Karst manifestations are widespread in many regions and pose a significant danger to residence and economic activity. Failing funnels arise during the collapse of rocks over underground voids (caves, workings, etc.), formed during karst formation or in the process of anthropogenic doing in the rock massive. However, not every karst or technogenic cavity gives rise to a failure of the earth’s surface, and as a rule, its occurrence is unexpected. In this work, we consider the dynamics of the formation of dips of the earth’s surface in the form of a collapse pipe. To do this, the geomechanical problem is solved by the meshless code Smoothed Particle Hydrodynamics (SPH). The method allows to obtain a solution to the problem taking into account large deformations and possible discontinuities in the process of changing the stress-strain state. The Drucker-Prager fracture criterion is used, the parameters of which change over time in accordance with the accumulation of damage, which determines the temporary development of the fracture process, its beginning and speed.

A Comparison of Smoothed Particle Hydrodynamics (SPH) and Coupled SPH-FEM Methods for Modeling Machining

2020 ◽  
Author(s):  
Nishant Ojal ◽  
Harish P. Cherukuri ◽  
Tony L. Schmitz ◽  
Adam W. Jaycox
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Solid Mechanics ◽  
Large Deformations ◽  
Computational Time ◽  
Depth Of Cut ◽  
Fe Model ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle

Abstract Smoothed Particle Hydrodynamics (SPH), a particle-based, meshless method originally developed for modeling astrophysical problems, is being increasingly used for modeling fluid mechanics and solid mechanics problems. Due to its advantages over grid-based methods in the handling of large deformations and crack formation, the method is increasingly being applied to model material removal processes. However, SPH method is computationally expensive. One way to reduce the computational time is to partition the domain into two parts where, the SPH method is used in one segment undergoing large deformations and material separation and in the second segment, the conventional finite element (FE) mesh is used. In this work, the accuracy of this SPH-FEM approach is investigated in the context of orthogonal cutting. The high deformation zone (where chips form and curl) is meshed with the SPH method, while the rest of the workpiece is modeled using the FE method. At the interface, SPH particles are coupled with FE mesh for smooth transfer of stress and displacement. The boundary conditions are applied to tool and FE zone of the workpiece. For comparison purposes, a fully-SPH model (workpiece fully discretized by SPH) is also developed. This is followed by a comparison of the results from the coupled SPH-FE model with the SPH model. A comparison of the chip profile, the cutting force, the von Mises stress and the damage parameter show that the coupled SPH-FE model reproduces the SPH model results accurately. However, the SPH-FE model takes almost 40% less time to run, a significant gain over the SPH model. Similar reduction in computation time is observed for in a micro-cutting application (depth of cut of 300 nm). Based on these results, it is concluded that coupling SPH with FEM in machining models decreases simulation time significantly while still producing accurate results. This observation suggests that three-dimensional machining problems can be modeled using the combined SPH-FEM approach without sacrificing accuracies.

scholarly journals PySPH: A Python-based Framework for Smoothed Particle Hydrodynamics

2021 ◽  
Vol 47 (4) ◽  
pp. 1-38
Author(s):  
Prabhu Ramachandran ◽  
Aditya Bhosale ◽  
Kunal Puri ◽  
Pawan Negi ◽  
Abhinav Muta ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Smoothed Particle Hydrodynamics ◽  
High Performance ◽  
Solid Wall ◽  
Rigid Body Dynamics ◽  
Particle Methods ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Sph Simulation ◽  
High Level

PySPH is an open-source, Python-based, framework for particle methods in general and Smoothed Particle Hydrodynamics (SPH) in particular. PySPH allows a user to define a complete SPH simulation using pure Python. High-performance code is generated from this high-level Python code and executed on either multiple cores, or on GPUs, seamlessly. It also supports distributed execution using MPI. PySPH supports a wide variety of SPH schemes and formulations. These include, incompressible and compressible fluid flow, elastic dynamics, rigid body dynamics, shallow water equations, and other problems. PySPH supports a variety of boundary conditions including mirror, periodic, solid wall, and inlet/outlet boundary conditions. The package is written to facilitate reuse and reproducibility. This article discusses the overall design of PySPH and demonstrates many of its features. Several example results are shown to demonstrate the range of features that PySPH provides.

Smoothed Particle Hydrodynamics with Stress Points and Centroid Voronoi Tessellation (CVT) Topology Optimization

2016 ◽  
Vol 13 (05) ◽  
pp. 1650031 ◽  
Author(s):  
Mir Ali Ghaffari ◽  
Shaoping Xiao
Keyword(s):  
Topology Optimization ◽  
Smoothed Particle Hydrodynamics ◽  
Voronoi Tessellation ◽  
Center Of Mass ◽  
Voronoi Cell ◽  
Optimization Method ◽  
Particle Methods ◽  
Approximation Accuracy ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

Various formulations of smoothed particle hydrodynamics (SPH) have been presented by scientists to overcome inherent numerical difficulties including instabilities and inconsistencies. Low approximation accuracy could cause a result of particle inconsistency in SPH and other meshfree methods. In this study, centroid Voronoi tessellation (CVT) topology optimization is used for rearrangement of particles so that the inconsistency due to irregular particle arrangement can be corrected. Using CVT topology optimization method, the SPH particles, which are generated randomly inside a predetermined domain, are moved to the centroids, i.e., the center of mass of the corresponding Voronoi cells based on Lloyd’s algorithm. The volume associated with each particle is determined by its Voronoi cell. On the other hand, it has been shown that particle methods with stress point integration are more stable than the ones using nodal integration. Conventional SPH approximations only use SPH particles, and it results in the so-called tensile instability. In this paper, a new approach of using stress points is introduced to assist SPH approximations and stabilize the SPH methods.

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