A Combined EFEM–Discrete Element Method Dynamic Model of Rotor–Bearing–Housing System

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Lijun Cao ◽  
Farshid Sadeghi ◽  
Lars-Erik Stacke
Keyword(s):  
Finite Element ◽  
Discrete Element Method ◽  
Critical Speed ◽  
Discrete Element ◽  
Housing System ◽  
Total Force ◽  
Ball Bearings ◽  
Deep Groove ◽  
Rotor Bearing ◽  
Element Method

In this paper, a model was developed to study the effects of rotor and support flexibilities on the performance of rotor–bearing–housing system. The system is composed of a flexible rotor and two supporting deep-groove ball bearings mounted in flexible bearing housings. The dynamics of the ball bearings were simulated using an existing dynamic bearing model, which was developed using the discrete element method (DEM). The explicit finite element method (EFEM) was used to model the flexibilities of the rotor and bearing support. In order to combine the dynamic bearing model with finite element rotor and support system, new contact algorithms were developed for the interactions between the various components in the system. The total Lagrangian formulation approach was applied to decrease the computational effort needed for modeling the rotor–bearing–housing system. The combined model was then used to investigate the effects of bearing clearances and housing clearances. And it was found that, as the rotor is deformed due to external loading, the clearances have a significant impact on the bearing varying compliance motion and reaction moments. Results also show that deformation of the flexible housing depends on the total force and moment generated within the bearing due to rotor deformation. The first critical speed of rotor was simulated to investigate the unbalance response of the rotor–bearing system. It was demonstrated that rotor critical speed has a significant effect on inner race displacement and reaction moment generated at bearing location.

scholarly journals Bionic Design of a Potato Digging Shovel with Drag Reduction Based on the Discrete Element Method (DEM) in Clay Soil

2020 ◽  
Vol 10 (20) ◽  
pp. 7096
Author(s):  
Junwei Li ◽  
Xiaohu Jiang ◽  
Yunhai Ma ◽  
Jin Tong ◽  
Bin Hu
Keyword(s):  
Discrete Element Method ◽  
Drag Reduction ◽  
Clay Soil ◽  
Clayey Soil ◽  
Reduction Rate ◽  
Compressive Force ◽  
Discrete Element ◽  
Soil Conditions ◽  
Total Force ◽  
Element Method

The resistance of ordinary potato digging shovels can increase dramatically when used in a clay soil because of the adhesion between the soil and shovel. In this paper, a new type of bionic potato digging shovel was designed to decrease adhesion. The bionic structural elements, i.e., scalelike units (S-U) were applied to the potato digging shovel with inspiration from pangolin scales. The discrete element method (DEM) considered cohesion was used to simulate the drag reduction performance in clayey soil conditions. An ordinary plane shovel (O-P-S) was used for comparison. Three indicators (total force, draft force and compressive force) were used to characterize the drag reduction performance. The effect of the design variables of the bionic structures (length [l] and height [h]) and the transversal and longitudinal arrangement spacing (S1 and S2) of the structures on the drag reduction performance were analyzed. The results showed that the drag reduction performance of the bionic shovels with suitable parameters was better than that of the O-P-S. The best bionic sample labeled as a bionic prototype had a 22.26% drag reduction rate during the soil bin test and a 14.19% drag reduction rate during the field test compared to the O-P-S.

scholarly journals The mechanism of emitter clogging analyzed by CFD–DEM simulation and PTV experiment

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401774302 ◽  
Author(s):  
Liming Yu ◽  
Na Li ◽  
Jun Long ◽  
Xiaogang Liu ◽  
Qiliang Yang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Single Particle ◽  
Phase Particle ◽  
Discrete Element ◽  
Main Stream ◽  
Total Force ◽  
Labyrinth Channel ◽  
Element Method

Small but complicated labyrinth channel emitters are easily clogged. In this study, computational fluid dynamics–discrete element method coupling approach was employed to investigate the mechanism of emitter clogging caused by particles in size of 65, 100, and 150 µm. Computational fluid dynamics used Navier–Stokes equation to analyze flow characteristics of continuous phase. Discrete element method used Newton’s laws of motion to measure single particle motion and group distribution of disperse phase. Particle tracking velocimetry was also utilized to follow the trajectories and velocity of single particle. Our results indicated that the smaller the particle size, the less the total force. Tiny sands were mainly influenced by drag forces. The amplitude between tooth tips was small. Particles moved basically in the main stream with fast velocity and short travel distance, thereby having good following performance. It took shorter time to reach micro-dynamic balance. Meanwhile, the amount of sediments in the labyrinth channel was less. Particles in size of 150 µm were mainly affected by inertial forces. They can easily enter vortex areas. Sands staying longer than 0.1 s in the labyrinth channel accounted for 37.9% of total number. Sand groups were mainly distributed at the inlet of labyrinth channel. The more sands trapped in vortex areas, the easier it was to precipitate and cause emitter clogging.

Stability Analysis of Mountain Slope Based on Finite Element and Discrete Element

2012 ◽  
Vol 170-173 ◽  
pp. 1087-1090
Author(s):  
Wei Bin Yuan ◽  
Cheng Min Ye ◽  
Ji Yao ◽  
Lie De Wang
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Slope Stability ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Soil Slope ◽  
Safety Factors ◽  
Mountain Slope ◽  
The Stability ◽  
Element Method

In recent year, the foundations of the stability analysis of slope were provided by the development of finite element and discrete element method. Using finite element and discrete element method, the stability analysis of three typical slopes of shiwu thorp of Quzhou was carried out. The safety factors of slope profile were obtained. Based on the judgment criterion of slope stability，the slopes stability of shiwu thorp was judged. The results showed that the way to analyze the stability of soil slope is feasible.

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