Abstract-only submissions

Abstract-only submissions to the 16th ISTVS European-African Regional Conference

1166 / Selection of energy saving engine mode based on the power delivery and fuel consumption of a 95-kW tractor during agricultural operations

Md Abu Ayub Siddique, Seung-Min Baek, Mo-A Son, Ye-In Song, and Yong-Joo Kim

Abstract: The objective of this article is to estimate the power delivery efficiency and fuel consumption based on engine modes. In this study, 95-kW powershift tractor was used to analyze the power delivery and estimate the fuel consumption during agricultural operations. The asphalt driving, plow and rotary tillage were conducted for the field the experiment at the engine modes of conventional, APS (Auto power shift) power, and APS ECO. To analyze the field condition, soil hardness, and soil water content were measured as well as soil sample was collected from the experimental site to analyze the soil texture using the USDA soil texture triangle. It is observed that the engine required powers at various engines have a significant different of the asphalt driving, plow, and rotary tillage. However, the axle powers at all engine modes for each operation showed almost similar due to the similar forward speed of the tractor. In case of fuel consumption, it was found that the fuel consumption at each engine mode has a significant different. It was also observed the APS ECO mode was the most economic compared to the conventional and APS power for the asphalt driving, plow and rotary tillage. Therefore, we recommend by this study to the users to perform the tractor at APS ECO engine mode for asphalt driving, plow, and rotary tillage considering fuel economic and high working load.

2297 / Traction effects on vertical and horizontal contact stresses and the risk of soil structure deformation

Loraine ten Damme, Lars J. Munkholm, Per Schjønning, Thomas Keller, Alvaro Calleja Huerta, and Mathieu Lamandé

Abstract: Arable soil is often exposed to high mechanical stresses during field operations, which bears a great risk of soil structure deformation. The stress state under the wheels determines whether a risk of soil compression and/or soil distortion prevails. However, soil compaction risk assessments typically consider the risk of compression from the applied load but neglect tractive forces and the risk of distortion. We investigated traction effects on both the vertical and horizontal (longitudinal) stress distributions near the tyre-soil interface as a next step in advancing more accurate predictions of soil structure deformation. Vertical and horizontal stress measurements were made during wheeling in a field experiment with stress transducers installed at 0.1 m depth. We studied the stress distributions of a tractor’s rear wheel (6.7 Mg, 650/60 R38, 80 kPa) that was towed (i.e., no traction) or pulling (i.e., with traction, about 42 kN drawbar pull) and compared these with estimated soil strengths. We show how traction influenced tyre-soil interaction and the risk of soil structure deformation. Among others, with traction the tyre-soil contact area was larger and the magnitude of vertical stress lower. This reduced the risk of soil compression noticeably. Soil shear strength was reduced due to reduced constraining normal load. The latter, in combination with higher horizontal stresses, increased the risk of soil distortion considerably. Our results highlight the importance of considering traction in soil compaction risk assessments. However, reliable assessments require incorporation of the risk of soil distortion in addition to the risk of soil compression.

3815 / Data measurement and performance evaluation of an electric all-wheel-drive tractor during plow tillage

Seung-Yun Baek, Yong-Joo Kim, Seung-Min Baek, Ji-Won Choi, and Min-Jong Park

Abstract: This study was conducted for basic research on AWD (all wheel drive) systems applicable to tractors as the need for research on electric AWD systems increases. The platform consists of an electric power transmission system consisting of 4 sets of electric motors, helical reducers and planetary reducers, wheels, and an electric system including chargers, batteries (LiFePO4), converters and inverter (motor controller). The data measurement system consisted of analog (current, traction force) and digital (battery voltage, current, motor rotation speed, SOC (state of charge) level, travel speed) components using a CAN (controller area network) bus. Data measured during plow tillage were analyzed and used to calculate the data such as motor power, motor torque, traction power, and driving power. The traction performance of the electric AWD tractor was evaluated using tractive efficiency (TE) using calculated values (traction power and driving power) and dynamic ratio (DR). This study presented limitations and improvement methods of electric AWD tractors through data analysis and comparison with conventional tractors. In future study, we plan to conduct research on optimization and performance verification of the electric AWD tractor that reflect improvements.

3859 / Analysis for dynamic characteristics of a tractor cabin during agricultural operations

Jong-Dae Park, Hyeon-Ho Jeon, Su-Young Yoon, Min-Jong Park, and Yong-Joo Kim

Abstract: This study was conducted to develop a dynamic characteristic control system for improving the cabin environment during agricultural operations. The specification of platform used in the study was a 67 kWclass tractor with a weight of 4,000 kg and dimensions of 4,020 × 2,270 × 2,790 mm (lenth × width × height), respectively. For measuring data of dynamic characteristic of the cabin, plow tillage and rotary tillage, which account for the largest proportion of the tractor operations, were selected for major operations. To measure data of dynamic characteristic of the cabin, which continuously changes during operations, an Ellipse Series INS with a built-in IMU was attached to the center of gravity of the cabin. During field test, the gear stages of plow tillage were B2 (5.1 km/h) and B3 (7.6 km/h), and the gear stages of rotary tillage were A3 (2.67 km/h) and A4 (3.66 km/h), which are the most commonly used. To analyze dynamic characteristic such as roll and pitch during operations according to the gear stages, the data showed by box plot. Roll and pitch average angles were -0.7° and 0.4°, respectively, for the plow tillage. Roll and pitch average angles were -0.8° and -0.1°, respectively, for the rotary tillage. As operations rate increased, the roll and pitch angles became larger, varying within a maximum range of 2°. As a result, it was determined that the rotary tillage showed a larger change compared to the plow tillage in the case of roll. Both operations showed a similar change in the case of pitch. Also, roll and pitch showed a larger change as the travel speed of each operation increased. In the future, we plan to conduct additional research on the hydraulic control system related to the cabin to provide a more comfortable workspace for operators.

3893 / Analysis of load factor and performance evaluation for developing an electric driven tractor

Min-Jong Park, Su-Young Yoon, Ji-Won Choi, Jong-Dae Park, and Yong-Joo Kim

Abstract: This study aims to develop a 44 kW electric driven tractor consisting of an E-driving system. Because electric tractor is in the design process, we installed a measurement system on a conventional agricultural tractor. Torquemeters were installed between wheels and axles to measure wheel torque, proximity sensors were installed to measure wheel rotation speed and GPS (Global Positioning System) was installed to measure driving speed of the tractor. Antenna, amplifier, and DAQ (Data Acquisition) were installed to transfer and store the measured data. Workload data were measured during plow tillage, rotary tillage, loader operations, asphalt and field driving. Measured data were converted for validation of designing a 44 kW electric driven tractor using an engine load factor. The average engine load factor was 0.51 for rotary tillage, 0.46 for plow tillage, 0.38 for asphalt driving, 0.17 for field driving and 0.09 for load operation. For gear stage L, plow tillage and loader operations were conducted within the maximum torque and rotary tillage, field and asphalt driving were performed within the rated torque. For gear stage M, the plow tillage and loader operations were conducted outside of the maximum torque, which were impossible to perform. For gear stage H, all operations except the asphalt driving were conducted outside of the maximum torque, which were impossible to perform. Thus, high-load operations such as plow tillage and loader operations can be conducted in gear stage L, and high-speed operations such as asphalt driving can be conducted with motor rated speed in gear stage H. Consequently, it is judged that an E-driving system consisting of a motor and range shift can perform the major operations of a 44 kW tractor depending on gear stages.

4336 / High-fidelity 3D-DEM simulation for wheel mobility in low gravity environment

Takuya Omura and Genya Ishigami

Abstract: The effect of gravity on wheeled rover mobility on loose soil remains a challenging issue. Among several experimental techniques, such as parabolic flight or reduced-weight tests simulating low gravity, the discrete element method (DEM) is one of the most promising methods for analyzing the wheel-soil interaction in various gravity environments. However, the mechanical parameters used in the DEM are often identified ambiguously or empirically, resulting in low-fidelity simulation results. In this study, we comprehensively calibrate the mechanical parameters of a lunar regolith simulant applicable to the 3D-DEM to simulate the effect of gravity on wheel mobility. The DEM parameters were determined from the experimental results of two tests: the direct shear test and the minimum density test. We then tested a rigid wheel on the lunar simulant using the DEM with calibrated parameters in the following conditions: (1) Earth gravity (1 G) with the wheel mass of M, (2) moon gravity (1/6 G) with the wheel mass of M, and (3) Earth gravity (1 G) with the reduced-mass of 1/6M. The simulation results show that the wheel sinkage and the slip ratio on the moon are almost equivalent to those on Earth. On the other hand, in the reduced-weight test, the wheel sinkage and the slip ratio were smaller than the moon's results. This result implies that the reduced-weight test might overestimate the wheel performance.

4508 / Semi-empirical terramechanics model for variable terrain height

Eric Karpman, Jozsef Kovecses, and Marek Teichmann

Abstract: Dynamic simulations of various types of off-road vehicles, from planetary rovers to agricultural equipment, have long relied on well-established semi-empirical terramechanics models. While these models do have drawbacks and reliability issues that have been addressed by numerous works in the decades since the models were first introduced, semi-empirical approaches remain one of the few ways to simulate realistic wheel-soil interaction in real-time. One of the drawbacks of these methods is that they are constrained by the assumption that the terrain is a flat plane. The models work by integrating normal and shear stresses along the wheel-terrain contact patch. The normal stress at each point along the contact patch is determined based on an equation that computes soil pressure based on semi-empirical parameters, the dimensions of the wheel and the sinkage of the wheel at that point. The sinkage at any given point along the contact patch is generally determined based on the distance between the point and the flat plane that defines the terrain. This means that the sinkage of each point along the contact patch is computed based on one constant initial terrain height. In this work, we propose a modified version of the semi-empirical model in which the terrain is defined as a height-field rather than a flat plane. Thus, more complex terrain shapes can be used in simulation. Of particular interests are terrains with varying slopes, steps, and terrain shapes that would result in gaps in the wheel-soil contact patch rather than a continuous patch.

4727 / Analysis of gear durability for agricultural tractor transmission

Seungmin Baek, Seungyun Baek, Hyeonho Jeon, and Yongjoo Kim

Abstract: The purpose of this study was to analyze gear durability of tractor transmission using simulation analysis. A field test was performed using a 86 kW class tractor and the type of gear failure was analyzed. A simulation model of the tractor transmission was developed and analyzed for the safety factor and lifespan by changing the material of the damaged gear. The field test was conducted for plow and rotary tillage and was completed after about 107 hours due to operational problems. After field test, it was found that range shift A and B gears were damaged. In order to advance durability of the transmission, four materials of alloy steel for machine structural use such as SCr420, SNCM220, SCM822, and SNC815 were selected, and the safety factor and service life of the damaged range shift gears were analyzed according to gear materials. As a result of simulation analysis, SCM822 material satisfied the target life and was selected as a material for change. Therefore, it is considered that the durability of the transmission has been secured by satisfying the target life.

4895 / Theoretical analysis and fem simulation of the interfacial forces between tracked vehicle and snow soil

Yan Qingdong, Zhu Ming, Wei Wei, Liu Cheng, Liu Jianfen, and Meng Qingkai

Abstract: Based on the pressure-sinkage characteristics and the shear force-shear displacement characteristics of snow under loading, unloading and reloading, theoretical models of vertical displacement distribution and vertical pressure distribution for snow and interfacial forces between track and snow under different driving conditions were built. A multi-body dynamics model of track and plastic material models of snow were built to simulate the interfacial forces of the track on snow. The results of plastic deformation and vertical pressure distribution of snow were extracted from the simulation results to verify the theoretical models. A muti-body dynamics model of articulated tracked vehicles was built, and the driving performance of it on snow was evaluated. An experimental study on articulated tracked vehicle driving in snow is carried out. By comparing the experimental results and the simulation results of the plastic deformation characteristics of snow under tracked vehicle loading, the correctness of the coupling simulation model and the theoretical model is verified.

4976 / Performance evaluation of autonomous driving lateral control simulation model of agricultural tractor

Moa Son, Hyeonho Jeon, Seungyun Baek, Yein Song, and Yongjoo Kim

Abstract: Interest in automation of agricultural machinery is increasing. Recently, performance evaluation studies using simulation models are being conducted to reduce time and cost. Therefore, in this study, the performance evaluation of the autonomous control model of an agricultural tractor was performed. The simulation model was developed using the specifications of a 78 kW tractor and the software RecurDyn. The input data was set as traction data from the six-component load cells, the rotational speed of each axle, and the position of the 3-point hitch. Validation of the simulation model was conducted by comparing the error between the measured data and simulation results. The performance evaluation of the steering control model was performed on the road model (friction coefficient conversion). The steering control model was configured to perform steering control by receiving the lateral error in real time from the dynamics model. A trial-and-error method was used to select coefficients for the autonomous control model. The RMS of the measured data was 3.29 and 3.44 for the anterior left and right sides, respectively, and 6.98 and 7.41 for the posterior left and right sides, respectively. The RMS of the simulation results were 3.24 and 3.53 for the anterior left and right side, respectively, and 8.26 and 8.55 for the posterior left and right side, respectively. The errors were 1% and 2% for the anterior left and right side, respectively, and 15% and 13% for the posterior left and right side, respectively. The error occurred within the range of about 10%, and it was judged appropriate to conduct research on performance evaluation using this model. The RMS according to the friction coefficient conversion was 3.7 and 4.5, respectively, showing a difference of about 1.

5356 / Development and validation of head-feeding combine harvester multibody dynamics simulation model

Cheol-Woo Yang, Hyeon-Ho Jeon, Min-Jong Park, Ji-Won Choi, and Yong-Joo Kim

Abstract: Head-feeding combine harvester are expensive and time-consuming to produce prototype, performance evaluation using simulation should be performed in the design stage. Recently, research has been conducted to solve these problems by replacing the driving test of agricultural machinery with simulation. In this study, a head-feeding combine harvester dynamics simulation model was developed and verified. The simulation model was developed using commercial software (Recurdyn, V9R4, Korea). The model development was performed using the specifications of a 6-row head-feeding combine harvester (CF690G, TYM, Korea). The speed condition of the simulation was set to 1.5 m/s. The simulation result set as the torque of the sprocket. For the development and validation of the simulation model, a measurement system was developed and installed on the head-feeding combine harvester. The driving test was conducted at the paddy field located in Dangjin, Chungnam (36°55'49.1"N, 126°37'57.3"E). The simulation was verified by comparing the measured data with the simulation results. The simulation results showed an average sprocket torque of approximately 1241.17 Nm. The measurement resulted in an average sprocket torque of approximately 1143.49 Nm. The error between the measured and simulated values is around 7%, and the measured and simulated values are similar. In the future research, the study to measure the load data during agricultural work and improve the simulation model using the load data will be conducted.

6059 / Comparison of multi-tracked running gears for light UGVs in terms of terrain obstacles overcoming abilities

Daniela Szpaczyńska, Marian Łopatka, and Piotr Krogul

Abstract: Rubber tracked running gears are widely used in high-mobility unmanned ground vehicle to increase the ability to overcome terrain obstacles that are often found in off-road terrain. The paper investigates the process of overcoming an obstacle by light unmanned ground vehicle using multibody dynamics simulations. The two-dimentional model of running gear was assumed and created in the ADAMS program environment. As well as the kinematics of the running system components, the flexibility of the elastomer belt and also the reactions of the tractive force in the track-ground contact surface were taken into account. On the basis of the simulations, the functionality of multi-track systems was compared with classic tracked systems. Properties that could be improved through the use of multi-tracked running gears in light land platforms were determined.

6143 / Flexible tire-terrain interaction model for real time simulations

Mahdi Maleki and Jozsef Kovecses

Abstract: The analysis of tire dynamics is important in the simulation of vehicle behaviours. The forces exerted on a tire depend on the tire and the terrain interaction at the contact patch, and the tire structure directly influences this interaction. Complex models with a high number of degrees of freedom, such as lumped parameter models or finite element models, are typically required to represent tire flexibility appropriately. Employing these models, however, can lead to high computational costs that can be a significant challenge for real-time simulation. In this work, we developed a reduced flexible tire model capable of representing the effect of tire flexibility to reduce the computational costs of the simulation. This model reduction is done by defining an effective stiffness of the flexible tire (which accounts for the effects of tire deformation at the contact patch) and augmenting it with the rigid wheel to represent the effect of stiffness at the contact patch. The flexible tire model, which has been used as a base, is a lumped parameter model in which the tire sidewall and belt are represented by a set of lumped point masses connected together and to the rigid wheel rim with sets of parallel spring and damper elements. In addition to reducing the degrees of freedom of the system, the proposed method makes it possible to perform the simulation with relatively large time steps, which significantly reduces the simulation run time. By this approach, we could achieve up to 25 times faster simulations compared to the ordinary model while maintaining adequate accuracy.

6211 / Wheel-soil terramechanics model augmentation using machine learning across multiple soil types

Eric Karpman, Jozsef Kovecses, and Marek Teichmann

Abstract: Terramechanics simulations for real time applications have primarily made use of traditional semi-empirical models since they are the only ones computationally efficient enough to run at real time interactive rates. A drawback to these models is that they are formulated based on an assumption that the wheel is operating under steady state conditions. This can adversely affect their accuracy or even their compatibility in dynamic simulations. Computationally demanding approaches such as the Finite Element Method (FEM) and the Discrete Element Method (DEM) address this issue, but the time required to run simulations is prohibitive for certain applications. We have previously proposed a method for real time terramechanics simulation that addressed the issue of the steady state assumption in the traditional semi-empirical models by using machine learning (ML) to augment the forces predicted by existing semi-empirical models in an effort to improve accuracy in dynamic simulations. By augmenting the semi-empirical predictions with ML rather than using ML to predict the total force, we aimed to preserve the insights provided by the semi empirical model. DEM experiments were run to establish a ground truth for the soil reaction forces, and at each time step we compared predictions of the semi-empirical model to those recorded in DEM simulations. We then train a ML model to augment the semi-empirical model to match DEM results. Our past work showed how this approach can work for a single soil type. Now, we will present the work with an expanded scope in which multiple soil types are used to train the ML algorithm - resulting in a single trained model that can be used for a variety of different soil types without the need to re-train the ML portion of the model each time.

6955 / Development of dynamics simulation model for agricultural tractor according to agricultural work

Hyeonho Jeon, Seungyun Baek, Seungmin Baek, Moa Son, and Yongjoo Kim

Abstract: The behavior of tractor is affected by the load. Especially, the behavior is significantly changed, an accident, such as rollover, is occurring. Therefore, the behavior of the vehicle affects work stability. To increase the work stability, it is necessary to predict the behavior of the vehicle by predicting the load occurred in a vehicle. This study was conducted as a basic study for the development of a tractor dynamics model. The simulation model was developed using a multi-body dynamics software and a steering controller for a simulation model. The specification of the tractor was 4,225 mm in length, 2,140 mm in width, 2,830 mm in height, and 3,985 kg. The center of gravity was 984 mm from the rear axle, 973 mm above ground, and 986 mm from the left side of the vehicle. Simulations were conducted during conditions of Plough tillage and condition of driving on a field. A field test was conducted to make and validate the simulation model. The measurement system is configured to measure traction, rotation speed, axle torque and behavior of a tractor. Traction and axle rotation speed were used as input data for simulation model. The load on axles and vehicle behavior were used as validation data for simulation. Field tests were conducted to measure input value and verify the simulation model. Field tests were conducted at M2 high (5.2 km/h ~ 6.7 km/h). Analysis between simulation result and measurement data showed that the difference in axle load was less than 10%. The load on axles can be predicted by using the developed model and evaluating the steering controller model can be conducted using this dynamics simulation model. In the next study, it is necessary to evaluate the steering controller model thorough the dynamics model.

7994 / Longitudinal friction coefficient comparison on actual and laboratory surfaces

Carl Becker and Schalk Els

Abstract: Tyre models used in soft soil simulation analysis requires tyre parameters in the form of stiffnesses in multiple di-rections. These parameters are obtained from measurements on hard terrain as these parameters are a function of the tyre carcass construction. Vehicles used on soft terrain are also used on hard terrain. Tyre testing is not a trivial or inex-pensive exercise and outdoor testing has limitations on repeatability. This is the case for testing on soft terrain/soil and hard terrain, thus it is preferred to conduct laboratory tests when characterizing tyres. This study investigates the longi-tudinal friction coefficient measured on surfaces with different surface roughness. The surface roughness has a direct influence on the friction coefficient generated by a tyre during tests. Tests are conducted on the actual concrete surface of interest, typically used in field tests. A mold is cast from the actual surface in order to replicate the same surface in laboratory conditions. Tests are then conducted on the replicat-ed surface and different sandpaper surfaces to determine which surface is the most representative in the laboratory. Multiple tyres are tested on the different surfaces and results compared.

8754 / Characterization of lunar simulant (FJS-1), toyoura sand, and silica sand with physical experiments and dem simulation

Isabel Casasbuenas, James Hurrell, Keisuke Takehana, and Kazuya Yoshida

Abstract: Geotechnical properties of the soils allow understanding of the mechanical behavior of soil under different stress conditions. However, the geomechanical properties of soils under Earth’s gravity are liable to be different from those under lunar gravity, making direct comparisons with experiments difficult. Therefore, Discrete Element Method (DEM) simulations can be used alongside physical experiments to study the geotechnical properties of the soil in a lunar environment. Understanding the mechanical behavior of the lunar soil will aid in performing future engineering operations such as mobility, construction, mining, and foundation design. Angle of Repose and Triaxial compression test simulations in lunar and terrestrial gravity environments were performed to understand soil behavior under these two environments. Angle of repose (AoR) testing used the fixed funnel method. A set volume and mass of material are poured through a funnel forming a pile below. A value is then measured for AoR which is related to the internal friction angle. Laboratory triaxial tests were performed on three specimens to simulate stress conditions and determine shear strength and other geotechnical properties under Earth’s gravity conditions. Vertical loads were applied at a 0.5 mm/min rate and confinement pressure from 10 to 60 kPa. Cohesion, soil stiffness, shear stress, and friction angle obtained from the triaxial and angle of repose tests are compared with the results obtained in DEM simulations. Exploring the difference between static and dynamic tests could contribute to understanding where physical properties of the lunar soil play a major role in the wheel soil interaction. The result of the present work will contribute to ongoing research in wheel-soil interaction.

8859 / An efficient and high-fidelity track model for dynamic simulation of off-road tracked vehicles

Oz Ben-Yosef and Dror Rubinstein

Abstract: A high-fidelity simulation model of tracked vehicles is required for proper prediction of the mobility of tracked vehicles traveling over soft soils. The vehicle components can be modelled using standard tools of multi-body programs. A track model was developed and successfully worked together with Altair's MotionSolve multi-body program. The model based on classic soil mechanics equations. The grousers, which are a significant part of many types of track-links, are taking into the account. The plasticity and viscosity properties of the soil are considered in the model. Verification tests were conducted in an agricultural field in the Jezreel Valley. The tests were run over soils with varying mechanical prop-erties, achieved through irrigation and tillage. The chosen test vehicle was an M113 armoured carrier. Several drawbar pull loads were applied on each soil condition. Reasonable correlation between the tests and simulation results were achieved. However, this model is not efficient and require consumption of large amount of CPU time. On the other hand, the more efficient models are based on simplifying assumptions with lack of accuracy. This work proposes a method for creating an efficient high-fidelity model. This can be implemented by representing the interaction between the track and the ground according to the previous work. The solution for the track-links will be done independently to the solu-tion of the entire vehicle. The solution of the track link will be obtained through a solver that will be developed for this purpose. The solution of the entire vehicle will be done by the solver of the multibody program (Altair MotionSolve). Good correlation between the efficient model and the previous model were achieved.

8963 / Analysis of the influence of terrain unevenness and velocity on the ground pressure exerted by demining rollers

Dariusz Kalinko, Marian Janusz Łopatka, Arkadiusz Rubiec, Mirosław Przybysz, and Piotr Krogul

Abstract: The effectiveness of demining rollers heavily depends on their performance in different terrains and operating conditions. Conventional demining roller structures with rigid wheels are widely used in demining operations, but their performance in real work conditions is still a significant scientific aspect. In this paper, the results of simulation tests conducted on demining roller systems with rigid wheels, without additional ground pressure systems are presented. A multi-body numerical model of a vehicle with a single demining section is described. The influence of terrain unevenness and velocity on the ground pressure exerted by roller is discussed.

9504 / Soil deformation model for efficient simulation of off-road vehicles and compaction force analysis

Yang Jiao and Jozsef Kovecses

Abstract: The performance evaluation of off-road vehicles is important since their operating environment is always complex. There are various types of models developed to predict vehicle soil interaction, ranges from semi-empirical models to discrete element(DEM) finite element based representations. For scenarios that require fast simulation, semi-empirical model is a better choice since it has the lowest computational cost. However, it does not incorporate the influence of soil deformation and has a quasi-static nature. To incorporate the influence of soil deformation, a new soil deformation model is proposed and developed. The geometry of the soil in this model is represented by using a height map with vertical layers. The soil deformation is separated into two parts and the total soil mass is conserved. The soil mass transmission resulted by vertical soil compaction is the main focus of this work, and it is captured by using a soil mass prediction neural network. The change in density and void ratio on each soil layer is then computed based on the mass transmission. The other part that resulted by tangential movements would also be briefly introduced. The data gathering is done by conducting Bevameter tests in DEM simulation environment by using EDEM. Various compaction tool widths, speeds and angles are used to generate the data for training and validation purposes. The influence of the compaction speed and angle on soil compaction force and soil skeleton states (e.g. density and void ratio at each layer) are also analyzed to investigate the possibility of optimizing the prediction of the Bekker pressure sinkage equation and the soil deformation model. The relation between Bekker parameters and general soil mechanics parameters is also discussed in this work.

9716 / Non-pneumatic tire for special vehicle – a review of selected functional properties

Marcin Żmuda, Jerzy Jackowski and Marcin Wieczorek

Abstract: The wheel is an important element of the vehicle, as it is the only one that has direct contact with the road. Pneumatic tires are the most commonly used on vehicles nowadays. The tires transfer traction forces and directional control of the vehicle, they affect on parameters of the contact patch and the enveloping properties. Those functions of tires require maintaining compressed air at a certain pressure inside the pneumatic tire. Losses of compressed air, as a result of damage to a pneumatic tire, makes it difficult or impossible to use it further. High reliability of tires and resistance to damage is particularly important in the case of special vehicles that move mainly in difficult terrain, e.g. soft soil, natural and artificial obstacles, objects with sharp edges. In those conditions, an alternative solution are non-pneumatic-tires, in which the function of compressed air has been taken over by the so-called supporting structure. Type of supporting structure, including shape and materials used, influence on the load -carrying mechanism, directional stiffness and pressures in the contact patch. The paper analyzes the method of shaping selected properties of non-pneumatic tires and the influence of the applied supporting structure on selected operational characteristics of non-pneumatic tires.

Last updated

© International Society for Terrain-Vehicle Systems :: www.istvs.org