Grouser Height Research Articles

Research on the shear stress and microscopic deformation mechanism of deep sea sediments under the action of tracked miner

The traction force of the tracked miner is primarily determined by the shear characteristics of deep-sea sediments. The influence of different parameters on the shear characteristics of deep-sea sediments and the particles change law of the soil–track interface are discussed. By constructing the relationship between the particles horizontal displacement and residual shear strength, a novel shear rheological damage model of deep-sea sediments considering the influence of grounding pressure is proposed, and the microscopic mechanism of shear displacement of deep-sea sediments is explained. The results show that the peak shear strength and residual shear strength increase significantly with the increase of grounding pressure, track length, grouser height and shear speed. Moreover, the particles within the soil–track interface move along the lower right of the vehicle operating direction during the shearing process under different working conditions, the change of particle spacing shows a non-linear trend, and a quantitative equation for the horizontal deformation of soil–track interface under the experimental conditions is constructed. Additionally, the new shear model has a high level of accuracy in fitting with the experimental data, the internal particle migration changes on the soil–track interface can be divided into four characteristics: compaction, failure, deformation and translation.

Understanding front-rear track effect of seabed mining vehicle and traction performance optimization

The dual-tracked deep-sea mining vehicles used for sea trials generally cannot meet the demands of large-scale manganese nodules production due to their inadequate load bearing and traction performance. Various seabed mining organizations have gradually started four-tracked mining vehicles as seabed traveling ore collection machines to meet the demand for enhanced tractive performance. A notable challenge encountered is the significant front-rear track effect observed when these vehicles navigate soft-cohesive sediments. Addressing this, our study introduces a novel design concept that involves setting the grouser heights with a deviation between the front and rear tracks, coupled with the development of a traction force-slip rate model inspired by this innovative approach. This model facilitates an in-depth analysis of the front-rear track effect, including phenomena such as deep sinkage and an increase in pitch angle experienced by vehicles on soft-cohesive terrains. It is calculated that the front and rear grouser deviation height of only 2 cm can improve the traction force by 21%. Utilizing the multi-body dynamics (MBD) method, we validated the effectiveness of this grouser height adjustment in mitigating front-rear track effects, demonstrating its potential to reduce sinkage by at least 30 mm and pitch angle by at least 0.3 degrees, thereby guiding the optimization strategy. Finally, through optimization simulation, we present optimized track structural parameter sets suitable for three types of seabed pavement, concluding that for soft silty soil, saturated high cohesive soil, and saturated soft sandy soil, the grouser deviation heights should be approximately 5.3, 4.1, and 2.0 cm, respectively. After applying the optimized track structural parameter sets, traction performance evaluation indexes, such as traction force and the traction force-disturbing area ratio, improved by at least 23.4% and 3.3%, respectively. Meanwhile, static sinkage was reduced by at least 21.4% across the three types of pavements.

Parameter optimization and tractive performance evaluation of tracked miner

Enhancing the traction performance of the tracked miner is crucial for ensuring smooth seabed operation. In this study, an experimental device for the interaction between track and deep-sea sediments was designed, aligning with the walking process of the tracked miner. The primary and secondary order of the influence of the driving parameters on the mechanical properties of the undisturbed deep-sea sediments was determined by an orthogonal test, and the pressure-sinkage model and shear stress–displacement model were constructed. Building upon the shear model and the vehicle ground mechanics theory, the driving mechanics model of the tracked miner in the seabed environment was derived, and the track structure and parameter optimization method were proposed. The results show that the experimental factors significantly influence the mechanical properties of undisturbed deep-sea sediments, with the order of influence being grounding pressure > grouser height > shear rate > track shoe length > track shoe width; By optimizing the structural parameters of the “Kunlong 500” tracked miner, the drawbar pull increased by 29.1%, and the sinkage depth reduced by 12.8%. This study quantitatively analyzes the influence of structural parameters in driving performance on the sinkage and shear characteristics of deep-sea sediments, and proposes a new method for optimizing the tractive parameters. It provides new insights for achieving efficient and environmentally friendly movement of tracked miner on the seabed.

Mechanical properties and soil failure process of interface between grouser of tracked mining vehicle and deep-sea sediment

Tracked mining vehicles (TMVs) are key equipment in deep-sea mining systems and can easily slip when walking on soft sediments on the seabed. Thus, it is important to investigate the effect of track parameters and grounding-specific pressure on the shear interaction between mining vehicles and sediment. The sediment was simulated using a mixture of bentonite and water, and a shear test of the track with a single grouser and sediment was conducted. A numerical model of the track–sediment shear test was established, and the shear strength and failure mode of the sediment soil under the track action were examined. The results demonstrate that the peak shear strength of the track–sediment interface increases with an increase in the grounding-specific pressure, gradually increases with an increase in grouser height, and tends to stabilize at a given level of grouser height. Owing to the presence of the grouser, the deep-sea sediment transitions from the elastic state to the plastic state faster than the typical clay during the shear test. The variation law of peak shear strength at the track-sediment interface with the height of track grouser under different grounding-specific pressures was analyzed, and a modified shear stress-displacement relationship model was proposed. Wedge failure is the predominant method of failure for a single-grouser shear sediment soil at various heights. The primary factor affecting the horizontal disturbance range is the grouser height, and the range increases as the grouser height increases; the primary element affecting the vertical disturbance range is the grounding-specific pressure, and the range increases as the grounding-specific pressure increases. The relationship of the grouser height and cohesiveness with the interfacial shear strength was examined and a new shear stress–displacement relationship model that can accurately capture the shear mechanical behavior between the track and sediment under various grouser heights was proposed. In conclusion, the study findings could serve as a guide for the engineering design of a TMV walking system.

Dynamic Traction of Deep-Sea Polymetallic Nodule Collector

The ocean is extremely rich in mineral resources. To cope with the shortage of land mineral resources, countries are focusing on the development of deep-sea mineral mining technology. Owing to its superior traction performance, the deep-sea polymetallic nodule collector (DPNC) has become the preferred solution for ocean mining. This paper proposes a dynamic traction calculation model to address the shortcomings in the classical static traction calculation model with consideration of the dynamic variation rule of grouser–soil interaction in the DPNC process. Lab tests were conducted to formulate materials similar to deep-sea soil, and the corresponding shear stress–displacement models were established using the discrete element method (DEM) and Magic Formula to describe the “shear stress–displacement” relationship more accurately. Considering Kunlong 500, which is a Chinese DPNC, as an example, the periodicity and dynamics of the dynamic traction force were analyzed and compared with the numerical simulation results. The dynamic traction force was smaller than the static traction force and fluctuated significantly when considering the dynamic grousers–soil interaction. The magnitude and fluctuation of the dynamic traction force were influenced by the ratio of the grouser height to the spacing. In the DPNC design, the ratio of the grouser height to the spacing should be optimized according to the properties of the deep-sea subsoil to improve the traction performance and stability of the DPNC.

Numerical Study on Multiple Parameters of Sinkage Simulation between the Track Plate of the Deep-Sea Mining Vehicle and the Seafloor Soil

The seafloor soil is characterized by high water content, strong compressibility, and low shear strength. Deep-sea mining vehicles (DSMV) are prone to sinking when walking on the surface of the soil, which will cause significant reduction in traction performance. Therefore, it is necessary to study the sinkage performance. The track is usually considered the travelling mechanism of the DSMV, and the track plate is an important part of the movement system. The study of the interaction between the track plate and the soil is of great significance to the study of the DSMV’s sinkage performance. In this study, firstly, based on the in situ seafloor soil samples of 1000 m in a region of the South China Sea collected by a box sampler, the physical and mechanical parameters of soil were measured by indoor geotechnical instruments. Secondly, an elastoplastic soil numerical model similar to that of in situ soil was established. Based on coupled Eulerian-Lagrangian (CEL) method, a numerical model of the interaction between the track plate and soil was established. Considering the dynamic process, the structure of the track plate and the physical and mechanical properties of the soil, the numerical simulation were carried out under different conditions, such as different dynamic loading, the plate structural parameters and the soil physical and mechanical properties. It is found that the plate-sinkage curve were significantly influenced by these factors. The findings are as follows, firstly, with the increase in the pressure loading rate, the soil sinkage decreasing at the same pressure. On the other hand, with the increase in velocity, soil flow was accelerated, and the nonlinear relationship between resistance and velocity became more obvious; the L/B ratio of different track plates affects the variation law of the curve, and the maximum sinkage gradually decreases as the ratio of L/B increases; with the increase in the grouser height, the maximum sinkage gradually decreases, and the pressure-sinkage curve changes obviously with the grouser type; and different soil physical and mechanical properties affect the variation of pressure-sinkage curve. Innovatively, the heterogeneous soil stress distribution mode was obtained through the fitting function and Python secondary development. This study can provide a reference for studying the sinkage performance of the DSMV.

Evaluation of the Soil Thrust on Continuous Tracks Considering Independent Soil Shearing by Grousers

Soil thrust is a traction force of an off-road tracked vehicle. Existing soil thrust assessment methods assume that a continuous shear failure plane exists along the soil-track interface. However, recent experimental works revealed that the soil beneath the track is divided into soil blocks; each soil block is sheared independently. This study proposed a new total soil thrust assessment method based on the block-shaped failure mechanism, and the total soil thrust predicted by the proposed and the existing methods was compared. The results showed that the existing method showed a greater maximum soil thrust at a lower slip rate than the proposed method. When the soil exhibited a hardening behavior, the total soil thrust in the existing method was always greater than that in the proposed method. However, when the soil exhibited softening behavior or hump behavior, the total soil thrust in the existing method was greater than that in the proposed method until a specific slip ratio, after which the latter became greater. Unlike the existing method, the proposed method can consider the difference in soil thrust with the grouser shape ratio, showing that the total soil thrust increased as the grouser height increased and the shape ratio decreased.

Analysis of Effect of Grouser Height on Tractive Performance of Tracked Vehicle under Different Moisture Contents in Paddy Soil

Grouser height and soil moisture content have a significant effect on the tractive performance of tracked vehicles. Paddy soil has the mechanical properties of both clay soil and sandy soil and can have a wide range of water content values, and it has a considerable influence on the tractive performance of tracked agricultural machinery. To study the influence of grouser height on the tractive performance of a single-track shoe under different soil moisture contents, a three-dimensional shearing model of the single-track shoe and the contact soil was established based on the ground vehicle mechanics theory, and an experimental platform with a soil bin, sensors, and a control system was established. Six preset levels of moisture contents (7%, 12%, 17%, 22%, 27%, and 32%) of paddy soil were prepared for the research experiment. The mechanical properties of the soil with different moisture contents were obtained through the use of a direct shear test, penetration test, and compaction test. The obtained physical parameters of the soil have special characteristics that are different from typical soil. Combined with the three-dimensional model and the obtained soil parameters, the parameters of the tractive performance, such as thrust, running resistance, and traction with different moisture contents were analyzed and calculated. The test results revealed that the thrust at different grouser heights shows a regular waveform growth trend with an increase in soil moisture content. The minimum value and the maximum value of thrust were obtained at moisture contents of 7% and 12%, respectively. The curve of different grouser heights of the running resistance shows similar changes with different moisture contents. The two peak points and inflection points of the fluctuation curve are for moisture contents of 17% and 27%. The change curve of the traction is highly similar to the curve of thrust. The maximum value of the traction was found at a moisture content of 12%, and the minimum value at 22% or 27%. Under different moisture conditions, tracked vehicles with higher grousers have better tractive performances.

The Measurement of Shear Characteristics of Paddy Soil in Poyang Lake Area

Understanding the shear characteristics of paddy fields is of great significance for the design of high-trafficability paddy wheels and to improve the trafficability of the tiller in paddy fields. Taking the paddy soil in Poyang Lake area of Jiangxi Province as the research object, a simple, self-designed bevameter was constructed to measure the apparent cohesion c and apparent internal friction angle φ of paddy soil with water content of 37% by weight using an annular shear plate. The effects of different shear speeds, shear grouser heights, and shear plate diameters on the measured c and φ were investigated. The measured values of c and φ were 1.89–2.35 kPa and 10.2–11.4°(deg), respectively. With the increase in shear speed, shear plate diameter, and grouser height, the value of c increased. Shear plate diameter and shear speed had small effect on c, whose change rate did not exceed 7.8%. However, shear grouser height had a greater influence on c, and the measured c increased by 24.5%. The influence of the three factors on φ followed the order: shear speed > shear plate diameter > shear grouser height, but the variation in φ did not exceed 1.2°(deg). The optimal operational conditions were: shear plate diameter of 250 mm with inner diameter of 150 mm, shear grouser height of 10 mm, with a shear speed of π/120 rad/s, and the apparent cohesion and apparent internal friction angle are 1887.8 pa and 11.06° (deg), respectively.

Research on the disturbance behaviour of the track chassis to the sand-gravel pavement during the steering process of the electric shovel based on DEM

To analyse and improve the disturbance behaviour of the track chassis to the sand-gravel pavement during the steering process of the electric shovel, the steering process of the electric shovel is taken as the specific analysis object, and the steering radius, the steering velocity, the grouser width, and the grouser height are regarded as influence factors. The disturbance prediction model of the electric shovel is established through the coupling method of discrete element method (DEM) and multi-body dynamics (MBD) and the Kriging model. On this basis, the steering disturbance behaviours of the track chassis to the sand-gravel pavement under different working conditions are obtained. Finally, taking variation coefficient ratio of ground pressure, power, and disturbance potential energy as the optimization goal, the multi-objective optimization based on genetic algorithm (GA) and the disturbance prediction model is implemented, and the corresponding optimization results are 6.02 m, 0.14 m/s, 19.61 mm, and 12.68 mm. The feasibility of the optimization results is then confirmed via comparison with ones of DEM-MBD coupling simulation, the results show that the variation coefficient ratio of ground pressure, power, and disturbance kinetic energy are reduced to varying degrees, and the disturbance potential energy is greatly improved. This indicates that the disturbance of the track chassis to the sand-gravel pavement has been improved, which is conducive to better steering of the electric shovel.

Numerical and Experimental Analyses of Track Shoe Patterns for Vehicle on Sandy Terrain

A track is a vehicle propulsion system that consists of a continuous band of chains connected with track shoes or may be entirely made of rubber. The track system is still commonly used on various vehicles, including bulldozers, excavators, tanks, and tractors, and has recently been used in lunar expedition vehicles. A tracked vehicle is mainly designed to provide better mobility in rough, uneven, or slippery terrain. The main component of the track system is track shoes or so-called grousers. This track shoe geometry will determine the tractive performance of the vehicle. If an incorrect shape is used, the excavator will most likely slip. The previous study approached this traction problem by using the semi-empirical method. However, until now, the track geometry and traction relation are still unclear. This research focuses on the effects of track shoe geometry on tractive performance and vehicle climbing ability. The analysis was mainly conducted with a DEM (Discrete Element Method) simulation. The result from the experimental test is also confirmed using a small-scale RC prototype on simulated terrain with different slope variations. It is proven that the grouser height directly affects the climbing performance of tracked vehicles. A higher grouser height proves to be better at a higher inclination slope. However, for a low inclination angle, the flattened track was better. The traction result from the EDEM simulation also yields a similar result. However, higher usable traction means more friction is generated; therefore, the track with higher traction also takes more energy to cover the same distance.

Discrete element method (DEM) simulation of single grouser shoe-soil interaction at varied moisture contents

The soil-tool interaction can effectively be modeled with discrete element method (DEM) when a proper contact model and DEM parameters are applied. The interaction of a single grouser shoe with clay loam terrain at varying moisture content was simulated using the discrete element approach. The study was consisted of three soil moisture contents which were dry (7.5%), moist (21.5%), and wet (38%) by dry weight basis with a single grouser shoe model with three grouser heights 60, 55, and 45 mm respectively. The simulation was performed by using EDEM 2018 software, and the contact model was Hertz Mindlin. The DEM parameters were calibrated for each moisture content after trials, and to validate the DEM simulation, soil-bin experiments were carried out. The DEM model has captured the actual conditions of soil particle collection and transportation. The maximum tractive force was generated at the interface of 45 mm height grouser with moist (21.5%) soil level. The simulation and experimental results were compared to determine the accuracy of the contact model. The minimum error (10.09%) was found for moist soil with 45 mm grouser height between simulated and experimental results. It was concluded that the developed DEM model is substantial and can be used to analyze the soil-track contact mechanism and the true shear condition between the single grouser shoe and the soil at higher moisture contents were obtained by DEM simulation.

Optimization of Structure Parameters of the Grouser Shoes for Adhesion Reduction under Black Soil

The black soil of Northeast China has a strong adhesion ability because of its unique physical properties, and the soil often adheres to the surface of the grouser shoes of tracked vehicles during the operation. The adhesion performance depends largely on structure parameters of the grouser shoes. The grouser height, the grouser thickness, and the grouser splayed angle were selected as structure parameters. The adhesion force and adhesive soil mass were selected as indicators of adhesion performance. Therefore, the mathematical model between structure parameters and response indicators was established by the response surface method (RSM). The optimal parameters combination was that the grouser height was 20 mm, grouser thickness was 6.34 mm, and grouser splayed angle was 40.45°. The average data of verification experiments occurred when the adhesion force reached 1.11 kPa and adhesive soil mass reached 22.68 g. Compared with the average value of un-optimized experiment results, the adhesion force and adhesive soil mass reduced by 12.84% and 4.63%, respectively. The relative error of the predicted values and measured values was less than 5%, proving the reliability of the regression models. This study could provide a reference method for parameters optimization, and a new structure of the grouser shoes of tracked vehicles will be designed to reduce adhesion.

Effect of track shoes structural parameters on traction performance of unmanned underwater tracked bulldozer

The unmanned underwater tracked bulldozer (UUTB) plays an essential role in emergency rescue caused by natural disasters. The traction force is produced by the interaction between the tracks and the soft sediments on the river bed. The structural parameter has great effects on the traction performance of the UUTB. To evaluate the traction performance produced by track shoes of the UUTB, the mechanical properties of π-shaped track, T-shaped track and V-shaped track are investigated in this paper. The length, width and grouser height of the tracks were changed to obtain the coupling mechanism between structural parameter and traction performance, which provides solid support for optimizing the track structural and improving the traction performance of the UUTB. Moreover, this work also provides dynamics fundamental for the control of anti-slip and stability of the UUTB.

Simulation and optimization of the tracked chassis performance of electric shovel based on DEM-MBD

To study and optimize the tracked chassis performance of electric shovel performance. First, the sand-gravel pavement model is built based on the discrete element method (DEM), and the virtual prototype model of the electric shovel is established. On this basis, the impacts of the pre-tension force, the road-wheel spacing, the sprocket speed, and the grouser height on the tracked chassis performance are explored by the coupling method of DEM and multi-body dynamics (MBD), and the performance prediction model of tracked chassis is obtained through Kriging interpolation method. Finally, taking ground pressure distribution, power, and track tension as the optimization goal, multi-objective optimization based on genetic algorithm (GA) and performance prediction model of tracked chassis is implemented, and the corresponding optimization values are 21,028 N, 1.10 rad/s, −12.97 mm, and 9.50 mm. The feasibility of the optimization results is then confirmed via comparison with results of DEM-MBD simulation, the results show that the power and tractive force are reduced to varying degrees, and the ground pressure variation coefficient and track tension are increased.

Effect of Grouser Height on the Tractive Performance of Single Grouser Shoe under Different Soil Moisture Contents in Clay Loam Terrain

The grouser height and soil conditions have a considerable influence on the tractive performance of single-track shoe. A soil bin-based research was conducted to assess the influence of grouser height on the tractive performance of single-track shoe at different moisture contents of clay loam soil. Eight moisture contents (7.5, 12, 16.7, 21.5, 26.2, 30.7, 35.8, and 38%) and three grouser heights (45, 55, and 60 mm) were comprised during this study. The tractive performance parameters of (thrust, running resistance, and traction) were determined by penetration test. A sensor-based soil bin was designed for penetration tests, which was included penetration system (AC motor, loadcell, and displacement sensor). The test results revealed that soil cohesion was decreased, and adhesion was increased after 16.7% moisture content. Soil thrust at lateral sides and bottom of grouser were increased before 16.7%, and then decreased for all the three heights but the major decrease was observed at 45 mm height. The motion resistance was linearly decreased, the more reduction was on 45 mm at 38% moisture content. The traction of the single-track shoe was decreased with a rise in moisture content, the maximum decrease was on 45 mm grouser height at 38% moisture content. It could be concluded that an off-road tracked vehicle (crawler combine harvester) with 45 mm grouser height of single-track shoe could be operated towards a moderate moisture content range (16.7–21.5%) under paddy soil for better traction.

Experimental evaluation of traction and coupling properties of terrain vehicles

The article demonstrates the results of the experimental evaluation of the traction and coupling properties of the wheeled utility terrain vehicles (UTV) during which parameters and indicators allowing for their use during designing of new generation UTVs are determined. This work demonstrates the results of the tests in determining maximum drawbar pull; determining maximum drawbar pull at snatch load of the Russian-made UTVs RM 650-2, Stels 800 Guepard and foreign-made UTVs Yamaha Grizzly, BRP Outlander Max XT, BRP Outlander 6x6, Polaris Sportsman 1000 equipped with wheels with grouser height of 15 to 40 mm.

Tractive performances of single grouser shoe affected by different soils with varied moisture contents

The objective of this study is to clarify the differences of tractive performances generated by the sandy loam-grouser system and the clay soil-grouser system. The tractive performances of the grouser/track shoes are widely researched by previous researchers. However, it is essential to illustrate the influences of the soil properties on the tractive performances of the grouser shoe. Sandy loam and clay soil were used as the test soils for investigating soil parameters in this study. Moisture contents of soil were from 7.5% to 27%, dry basis. Parameters of sandy loam were obtained through direct shear tests, penetration tests, bulk density, and moisture content measurements in laboratory. The grouser shoe was made of steel. Based on the prediction result of tractive performances, the clay soil will always be performed better than the sandy loam no matter which dimension was chosen for single grouser shoe. Based on the experimental results, the grouser height of the track should be 5 cm in order to provide enough traction force, if a tracked vehicle is operated on the environment of either clay soil or sandy loam.

Effect of grouser height on tractive performance of tracked mining vehicle

The aim of this study is to establish a single track shoe with grouser driving model to optimize the track structural parameters and improve the tractive performance of the tracked mining vehicle on soft sediments. The calculation formula of each component force and total driving force about grouser height was obtained through theoretical analysis. The basic parameters and the relationship of mechanical properties for computer simulation were also obtained by the testing experiment using soil simulation whose main physical and mechanical properties are close to the deep-sea sediments. The computer simulation results show that the total driving force of the track improved rapidly with the increases of the grouser height and the slip rate. It keeps rising until it reaches a maximum value. And then it will maintain a steady value when the slip rate exceeds 40 %. The total driving force also improved with the increase of the ratio (slip rate/grouser height). When the grouser height is in the range of 0–15 cm, the total driving force keeps increasing gradually with the increase of the slip rate until it reached the stable state. When the grouser height is in the range of 15–30 cm, the total driving force keeps increasing to a maximum value rapidly with the increasing of slip rate first, and then keeps decreasing gradually. The greater the increase of grouser height, the faster the decrease of the total driving force.

A calculation method of track shoe thrust on soft ground for splayed grouser

Thrust of track shoes on soft ground is affected by soil moisture content, shear rate and structure parameters of track shoes. A lack of comprehensive consideration of these factors exists for normal calculation methods. A method to predict thrust for track shoes on soft ground with splayed grouser was established based on experimental results and theoretical derivations. Model track shoe traction experiments were conducted for verification and correction of the thrust formula. It was observed that the thrust for the track shoes decreased with the increase in moisture content of the soil. Increases in shear rate, grouser height, and grouser splayed angle resulted in greater tractions. Effect of grouser thickness and grouser draft angle on tractions was not obvious. A corrected thrust formula allowed accurate prediction of thrust for a single track shoe on soft ground.