Multigrain Smoothed Particle Hydrodynamics and Hertzian Contact Modeling of the Grinding Force in Atherectomy

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Yihao Zheng ◽  
Yao Liu ◽  
Yang Liu ◽  
Albert J. Shih
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Cutting Forces ◽  
Grinding Force ◽  
Grinding Wheel ◽  
Hertz Contact ◽  
Grinding Forces ◽  
Calcified Plaque ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

This study investigated the grinding force in rotational atherectomy, a clinical procedure that uses a high-speed grinding wheel to remove hardened, calcified plaque inside the human arteries. The grinding force, wheel motion, and ground surface were measured based on a ring-shape bovine bone surrogate for the calcified plaque. At 135,000, 155,000, and 175,000 rpm wheel rotational speed, the grinding forces were 1.84, 1.92, and 2.22 N and the wheel orbital speeds were 6060, 6840, and 7800 rpm, respectively. The grinding wheel was observed to bounce on the wall of the bone surrogate, leaving discrete grinding marks. Based on this observation, we modeled the grinding force in two components: impact and cutting forces. The impact force between the grinding wheel and the bone surrogate was calculated by the Hertz contact model. A multigrain smoothed particle hydrodynamics (SPH) model was established to simulate the cutting force. The grinding wheel model was built according to the wheel surface topography scanned by a laser confocal microscope. The workpiece was modeled by kinematic-geometrical cutting. The simulation predicted a cutting force of 41, 51, and 99 mN at the three investigated wheel rotational speeds. The resultant grinding forces, combining the impact and cutting forces modeled by the Hertz contact and SPH simulation, matched with the experimental measurements with relative errors less than 10%.

scholarly journals Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2314 ◽  
Author(s):  
Shu Wang ◽  
Anping Shu ◽  
Matteo Rubinato ◽  
Mengyao Wang ◽  
Jiping Qin
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
The Impact ◽  
Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

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.

scholarly journals Application of Smoothed Particle Hydrodynamics (SPH) for the Simulation of Flow-like Landslides on 3D Terrains

2022 ◽  
Author(s):  
Binghui Cui ◽  
Liaojun Zhang
Keyword(s):  
Risk Assessment ◽  
Smoothed Particle Hydrodynamics ◽  
Disaster Mitigation ◽  
Sph Method ◽  
Landslide Event ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Simulation Results ◽  
Mitigation Design ◽  
The Impact

Abstract Flow-type landslide is one type of landslide that generally exhibits characteristics of high flow velocities, long jump distances, and poor predictability. Simulation of it facilitates propagation analysis and provides solutions for risk assessment and mitigation design. The smoothed particle hydrodynamics (SPH) method has been successfully applied to the simulation of two-dimensional (2D) and three-dimensional (3D) flow-like landslides. However, the influence of boundary resistance on the whole process of landslide failure is rarely discussed. In this study, a boundary algorithm considering the friction is proposed, and integrated into the boundary condition of the SPH method, and its accuracy is verified. Moreover, the Navier-Stokes equation combined with the non-Newtonian fluid rheology model was utilized to solve the dynamic behavior of the flow-like landslide. To verify its performance, the Shuicheng landslide event, which occurred in Guizhou, China, was taken as a case study. In the 2D simulation, a sensitivity analysis was conducted, and the results showed that the shearing strength parameters have more influence on the computation accuracy in comparison with the coefficient of viscosity. Afterwards, the dynamic characteristics of the landslide, such as the velocity and the impact area, were analyzed in the 3D simulation. The simulation results are in good agreement with the field investigations. The simulation results demonstrate that the SPH method performs well in reproducing the landslide process, and facilitates the analysis of landslide characteristics as well as the affected areas, which provides a scientific basis for conducting the risk assessment and disaster mitigation design.

Analysis of surface-erosion mechanism due to impacts of freely rotating angular particles using smoothed particle hydrodynamics erosion model

2017 ◽  
Vol 231 (12) ◽  
pp. 1537-1551 ◽  
Author(s):  
Xiangwei Dong ◽  
Zengliang Li ◽  
Qi Zhang ◽  
Wei Zeng ◽  
G.R. Liu
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Impact Angle ◽  
Surface Erosion ◽  
Free Rotation ◽  
Erosion Model ◽  
Erosion Mechanism ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact ◽  
Angular Particles

The free rotation of an angular particle during its impact on ductile surfaces is an important factor that influences the erosion mechanism. However, the phenomenon cannot be easily revealed experimentally because the incident conditions cannot be accurately controlled. In this study, a novel erosion model based on smoothed particle hydrodynamics method is proposed to simulate single and multiple impacts of particles with specified angularities on a ductile surface. The model can simulate a particle having free rotation during the impact process and initial rotation prior to the impact. The results show that the impact angle and initial orientation significantly affect the tumbling behavior, which determines the erosion mechanism. Moreover, the initial rotation is investigated by assigning an initial angular velocity to the particle at the onset of impact. The proposed smoothed particle hydrodynamics erosion model is proven to be a promising complementary method that supports experimental techniques. This study provides insight for understanding the fundamental mechanisms of surface erosion due to angular particles.

scholarly journals Numerical Simulation of Impact Behavior of Ceramic Coatings Using Smoothed Particle Hydrodynamics Method

2020 ◽  
pp. 1-25
Author(s):  
Jian Zhang ◽  
Zhe Lu ◽  
Sugrim Sagar ◽  
Hyunhee Choi ◽  
Heesung Park ◽  
...  
Keyword(s):  
Spherical Particle ◽  
Smoothed Particle Hydrodynamics ◽  
Coating Layer ◽  
Ceramic Coatings ◽  
Impact Angle ◽  
Impact Behavior ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

Abstract In this work, the impact behavior of an alumina spherical particle on alumina coating is modeled using the smoothed particle hydrodynamics (SPH) method. The effects of impact angle (0°, 30°, and 60°) and velocity (100 m/s, 200 m/s, and 300 m/s) on the morphology changes of the impact pit and impacting particle, and their associated stress and energy are investigated. The results show that the combination of impact angle of 0° and velocity of 300 m/s produces the highest penetration depth and largest stress and deformation in the coating layer, while the combination of 100 m/s & 60° causes the minimum damage to the coating layer. This is because the penetration depth is determined by the vertical velocity component difference between the impacting particle and the coating layer, but irrelevant to the horizontal component. The total energy of the coating layer increases with the time, while the internal energy increases with the time after some peak values, which is due to energy transmission from the spherical particle to the coating layer and the stress shock waves. The energy transmission from impacting particle to coating layer increases with the increasing particle velocity, and decreases with the increasing inclined angle. The simulated impact pit morphology is qualitatively similar to the experimental observation. This work demonstrates that the SPH method is useful to analyze the impact behavior of ceramic coatings.

scholarly journals Pressure evaluation during dam break using weakly compressible SPH

2019 ◽  
Vol 213 ◽  
pp. 02030
Author(s):  
Petr Jančík ◽  
Tomáš Hyhlík
Keyword(s):  
Experimental Data ◽  
Smoothed Particle Hydrodynamics ◽  
Two Dimensions ◽  
Dam Break ◽  
Kinematics And Dynamics ◽  
Sph Method ◽  
Weakly Compressible ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

This paper presents a solution of a dam break problem in two dimensions obtained with smoothed particle hydrodynamics (SPH) method. The main focus is on pressure evaluation during the impact on the wall. The used numerical method and the way of pressure evaluation are described in detail. The numerical results of the kinematics and dynamics of the flow are compared with experimental data from the literature. The abilities and limitations of the used methods are discussed.

scholarly journals Numerical modelling of extreme waves by Smoothed Particle Hydrodynamics

2011 ◽  
Vol 11 (2) ◽  
pp. 419-429 ◽  
Author(s):  
M. H. Dao ◽  
H. Xu ◽  
E. S. Chan ◽  
P. Tkalich
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Rogue Waves ◽  
Offshore Structures ◽  
Wave Crest ◽  
Extreme Waves ◽  
Coastal Structures ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact ◽  
The Waves

Abstract. The impact of extreme/rogue waves can lead to serious damage of vessels as well as marine and coastal structures. Such extreme waves in deep water are characterized by steep wave fronts and an energetic wave crest. The process of wave breaking is highly complex and, apart from the general knowledge that impact loadings are highly impulsive, the dynamics of the breaking and impact are still poorly understood. Using an advanced numerical method, the Smoothed Particle Hydrodynamics enhanced with parallel computing is able to reproduce well the extreme waves and their breaking process. Once the waves and their breaking process are modelled successfully, the dynamics of the breaking and the characteristics of their impact on offshore structures could be studied. The computational methodology and numerical results are presented in this paper.

scholarly journals Study of the Influence of Cutting Regime Parameters on Grinding Forces in Processing Tungsten Carbide Dk460uf

2014 ◽  
Vol 65 (1) ◽  
pp. 87-92
Author(s):  
Silvia Vulc
Keyword(s):  
Tungsten Carbide ◽  
Cutting Forces ◽  
Normal Component ◽  
Grinding Force ◽  
Tangential Component ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Test Results ◽  
Tungsten Carbides ◽  
Grinding Forces

Abstract This paper presents a study on grinding tungsten carbide DK460UF, through experimental investigation using diamond grinding wheel with 54 μm grain size. Different sets of experiments were performed to study the effects of the independent grinding parameters such as grinding wheel speed, feed and depth of cut on cutting forces. Test results showed that the feed and depth of cut influence significantly the cutting forces. The research was lead to optimize the process parameters for reducing cutting forces. In this way, for different parameters of cutting regime, it were measured the values of the components of the grinding force, tangential component, Ft and normal component Fn. The results of the experiment showed that it is better to use great speeds and small feed rate and depth of cut in grinding tungsten carbides, such as DK460UF

Rigid-Object Water-Entry Impact Dynamics: Finite-Element/Smoothed Particle Hydrodynamics Modeling and Experimental Validation

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Ravi Challa ◽  
Solomon C. Yim ◽  
V. G. Idichandy ◽  
C. P. Vendhan
Keyword(s):  
Finite Element ◽  
Smoothed Particle Hydrodynamics ◽  
Material Strength ◽  
Water Impact ◽  
Numerical Predictions ◽  
Wide Range ◽  
Particle Hydrodynamics ◽  
Drop Tests ◽  
Smoothed Particle ◽  
The Impact

A numerical study on the dynamic response of a generic rigid water-landing object (WLO) during water impact is presented in this paper. The effect of this impact is often prominent in the design phase of the re-entry project to determine the maximum force for material strength determination to ensure structural and equipment integrity, human safety and comfort. The predictive capability of the explicit finite-element (FE) arbitrary Lagrangian-Eulerian (ALE) and smoothed particle hydrodynamics (SPH) methods of a state-of-the-art nonlinear dynamic finite-element code for simulation of coupled dynamic fluid structure interaction (FSI) responses of the splashdown event of a WLO were evaluated. The numerical predictions are first validated with experimental data for maximum impact accelerations and then used to supplement experimental drop tests to establish trends over a wide range of conditions including variations in vertical velocity, entry angle, and object weight. The numerical results show that the fully coupled FSI models can capture the water-impact response accurately for all range of drop tests considered, and the impact acceleration varies practically linearly with increase in drop height. In view of the good comparison between the experimental and numerical simulations, both models can readily be employed for parametric studies and for studying the prototype splashdown under more realistic field conditions in the oceans.

Numerical study on debris flow in step-pools channel using smoothed particle hydrodynamics method

2020 ◽  
Author(s):  
Shuai Li ◽  
Xiaoqing Chen ◽  
Chong Peng ◽  
Jiangang Chen
Keyword(s):  
Debris Flow ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Impact Force ◽  
Numerical Study ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Peak Impact Force

<p>Drainage channel with step-pool systems are widely used to control debris flow. However, the blocking of debris flow often gives rise to local damage at the steps and baffles. Hence, the estimation of impact force of debris flow is crucial for design step-pools channel. This paper presents a numerical study on the impact behavior of debris flows using SPH (Smoothed Particle Hydrodynamics) method. Some important parameters, such as the baffle shape (square, triangle, and trapezoid) and the densities of debris flows are considered to examine their influence on the impact force. The results show that the largest peak impact force is obtained at the second last baffle, rather than the first baffle. Moreover, the square baffle gives rise to the largest impact force whereas the triangle baffle bears the smallest one among the three baffles. Generally, the peak impact force increases with increasing the inflow density. However, a threshold density, beyond which the peak impact force will decrease, is suggested by the simulations. Based on the numerical results, an improved expression to predict the impact force considering the inclined angle of baffle is proposed.</p>

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