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.

Drag reduction and wear resistance mechanisms of a bionic shovel by discrete element method simulation

SIMULATION ◽  
2018 ◽  
Vol 95 (3) ◽  
pp. 231-239 ◽  
Author(s):  
Rui Zhang ◽  
Dianlei Han ◽  
Yuan He ◽  
Haijin Wan ◽  
Songsong Ma ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Drag Reduction ◽  
High Speed ◽  
Three Dimensional ◽  
Discrete Element ◽  
Resistance Mechanisms ◽  
Fatigue Wear ◽  
Soil Particles ◽  
The Common ◽  
Element Method

The ostrich has a steady and enduring high-speed running ability. Toenails are one key part of ostrich feet and their unique morphology is crucial in insertion into sand and for traction provision. In this study, information of bionic curves was extracted through studying the toenail structure and morphology, and three-dimensional reconstruction of toenails by reverse engineering. Based on the principle of bionic engineering, a bionic shovel was designed by optimizing the traditional shovel. A shovel–soil interaction mechanical model was established via the discrete element method. The insertion into soil processes of the bionic shovel and the common plate were simulated. The dynamic mesoscopic mechanical behaviors of soil particles around the shovel surface, the contact force field, and the velocity field, as well as the forces acting on the shovel surface were analyzed. The bionic shovel outperformed the common plate in insertion. The main reason for drag reduction in the bionic shovel was the inner concave bending surface, along which the soil particles climbed, and the particle movement trend was consistent. Simulations showed stress concentrated at the tip of the shovel, which facilitated the production of fatigue wear. Therefore, the tip needs to be considered firstly during bionic shovel design in the future.

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.

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 Effects of screw pile installation on installation requirements and in-service performance using the Discrete Element Method

2020 ◽  
Author(s):  
Yaseen Umar Sharif ◽  
Michael Brown ◽  
Benjamin Cerfontaine ◽  
Craig Davidson ◽  
Matteo Oryem Ciantia ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Large Diameter ◽  
Compressive Force ◽  
Vertical Displacement ◽  
Discrete Element ◽  
Service Performance ◽  
Pile Installation ◽  
Screw Pile ◽  
Torque Capacity ◽  
Element Method

Existing guidance on the installation of screw piles suggest that they should be installed in a pitch-matched manner to avoid disturbance to the soil which may have a detrimental effect on the in-service performance of the pile. Recent insights from centrifuge modelling have shown that installing screw piles in this way requires large vertical compressive (or crowd) forces, which is inconsistent with the common assumption that screw piles pull themselves into the ground requiring minimal vertical compressive force. In this paper, through the use of the Discrete Element Method (DEM), the effects of advancement ratio, i.e. the ratio between the vertical displacement per rotation to the geometric pitch of the helix of the screw pile helix, on the installation resistance and in-service capacity of a screw pile is investigated. The findings are further used to assess the applicability of empirical torque capacity correlation factors for large diameter screw piles. The results of the investigation show that it is possible to reduce the required vertical compressive installation force by 96% by reducing the advancement ratio and that although over-flighting a screw pile can decrease the subsequent compressive capacity, it appears to increase the tensile capacity significantly.

scholarly journals Analysis of Adhesion between Wet Clay Soil and Rotary Tillage Part in Paddy Field Based on Discrete Element Method

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 845
Author(s):  
Jian Cheng ◽  
Kan Zheng ◽  
Junfang Xia ◽  
Guoyang Liu ◽  
Liu Jiang ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Regression Model ◽  
Paddy Field ◽  
Clay Soil ◽  
Static Friction ◽  
Discrete Element ◽  
Rolling Friction ◽  
Soil Particles ◽  
Simulation Parameters ◽  
Element Method

To analyze the process of wet clay soil adhering to the rotary tillage part during rotary tillage in paddy field, simulation tests were carried out based on the discrete element method (DEM) in this study. The Plackett-Burman (PB) test was applied to obtain simulation parameters that significantly affected the soil adhesion mass. The Box-Behnken design (BBD) based on the principle of response surface method (RSM) was used to establish a regression model between significant parameters and soil adhesion mass. The soil adhesion mass obtained from the actual soil bin test as the response value was brought into the regression model. The optimal simulation parameters were obtained: the particle-particle coefficient of rolling friction, the particle-geometry coefficient of static friction, and the particle-particle JKR (Johnson-Kendall-Roberts) surface energy were 0.09, 0.81, and 61.55 J·m−2, respectively. The reliability of the parameters was verified by comparing the soil adhesion mass obtained under the optimal simulation parameters with the actual test value, and the relative error was 1.84%. Analysis of the rotary tillage showed that soil adhesion was mainly concentrated in the sidelong section of the rotary blade. The maximum number of upper soil particles adhering to the rotary tillage part was 2605 compared to the middle soil and lower soil layers. The longer the distance the rotary tillage part was operated in the soil for, the more soil particles would adhere to it. This study can provide a reference for the rational selection of simulation parameters for rotary tillage and the analysis of soil adhesion process in rotary tillage.

Discrete element method to model cracking for two layer systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Discrete Element Method ◽  
Flexural Modulus ◽  
Single Layer ◽  
Discrete Element ◽  
Flexural Stress ◽  
Layer System ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Layers ◽  
Element Method

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.

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