Draught force prediction from soil relative density and relative water content for a non-winged chisel blade using finite element modelling

Mohadeseh Arefi, Seyed Hossein Karparvarfard, Hadi Azimi-Nejadian, Mojtaba Naderi-Boldaji

Journal of Terramechanics, Volume 100, 2022, Pages 73-80, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2022.01.001.(https://www.sciencedirect.com/science/article/pii/S0022489822000015)

Abstract: This study aims to develop a model for prediction of the draught force of a new narrow non-winged chisel blade as a function of tillage depth (d), forward speed (v), soil relative water content (wrel), and soil relative density (ρrel) based on combination of statistical and finite element (FE) models. The soil-chisel blade interaction was simulated for various combinations of relative density and relative water content of a sandy loam soil at three levels of forward speed (i.e., 2, 3, and 5 km h−1) and three levels of tillage depths (i.e., 0.15, 0.2, and 0.25 m) using finite element method. The draught force of each simulation was obtained and used to develop a statistical model. A simple model with an adjusted coefficient of determination (Radj2) of 0.81 and the root mean square error (RMSE) of 0.3 kN was proposed for draught force. This model was tested for a set of experimental data obtained in a clay loam soil. The fitted regression line to the data showed that the predicted draught forces lie within bounds of ±6% of the measured values with a coefficient of determination of 0.96. In general, the results of this study showed that using relative density and relative water content, a prediction model could be developed for draught force to work across soil textures. Further studies in a wider range of soil textures are suggested to evaluate the model for the tillage tool.

Keywords: Soil-tool interaction; FEM; Draught force

Monitoring soil state during compaction process using a vibrating rammer and a plate compactor

Kwaśniewski Arkadiusz, Maciejewski Jan, Bąk Sebastian

Journal of Terramechanics, Volume 100, 2022, Pages 61-72, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2022.01.002.(https://www.sciencedirect.com/science/article/pii/S0022489822000027)

Abstract: The aim of the work was to compare the operation of the proprietary intelligent compaction (IC) system for two types of machines: a vibrating rammer and a plate compactor. The tests were carried out for both types of machines on the field stand, using the analysis of the vibroacoustic signal received from the acceleration sensor located directly on the machine. The developed system allowed to determine the correlation of the parameters Q1 and Q2 with the degree of compaction of the studied soil. These parameters were also compared with commonly used (CMV and CCV) by leading manufacturers of compaction machines.

Keywords: Intelligent compaction; Density of soil; Soil resonance frequencies; Compaction parameters

Soil compaction due to agricultural machinery impact, Journal of Terramechanics

Zoran I. Mileusnić, Elmira Saljnikov, Rade L. Radojević, Dragan V. Petrović

Volume 100, 2022, Pages 51-60, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.12.002.(https://www.sciencedirect.com/science/article/pii/S0022489821001038)

Abstract: Tillage involves various complex mechanisms of mechanical disturbance of the soil, aimed to advance its physical structure by creating relevant conditions for growing crops Quality regulation of every specific tillage conception is critical for the soil physical parameters. Thus, the main goal of this work was to review approaches to the analysis of the quality of soil cultivation techniques. Relationships have been established between the basic operating parameters of the mechanization applied and the consequent particle size spreading of the soil. Supplementary, statistical indices of the distribution pattern of soil particles, based on higher-order dimensionless statistical parameters were estimated. The observed mass distributions of soil aggregates was the result of extremely complex and superimposed influences of soil type, field conditions, crop structure, equipment used, etc. At this stage, an accurate forecast of the impact of soil tillage techniques on the changes in composition and size distribution of soil aggregates based on mathematical modelling is very difficult. Further research will be continued to include wider range of soil types, agricultural mechanization systems and their operational regimes.

Keywords: Terra-mechanics; Aggregates; Size distribution; Tillage system; Higher order statistics

Experimental analysis of mechanical properties of coastal terrain via bevameter tests

Ji-Tae Kim, Dongu Im, Jung-Ho Park, Hyuek-Jin Choi, Jae-Won Oh, Seung-Je Cho, Young-Jun Park

Journal of Terramechanics, Volume 100, 2022, Pages 39-50, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.12.001.(https://www.sciencedirect.com/science/article/pii/S0022489821001026)

Abstract: The driving performance of off-road vehicles is determined by the interaction between the terrain and the driving device. This study measured the mechanical properties of coastal terrain using a bevameter to predict the driving performance of vehicles driving along the coast. The results of the pressure-sinkage test on the dry terrain confirmed that there could be a relative error of approximately 10% between the test value and the predicted value of the pressure-sinkage characteristic equation. Thus, it was confirmed that an error of approximately 10% should be taken into account when predicting the driving performance of the vehicle. Shear tests on the dry terrain and saturated terrain confirmed that even the same soil texture had different shear behaviors depending on saturation. In addition, the maximum shear stress showed a significant difference, but the shear stress after the critical state showed no significant difference. Finally, the shear test was carried out by varying the number and height of the grouser to confirm the grouser effect. The grouser effect test results confirmed that the number of grousers does not have a significant effect on the shear stress, but the height of the grouser does have an effect on the shear stress.

Keywords: Soil property; Driving performance; Shear behavior; Off-road vehicle; Bevameter

Review of compressed snow mechanics: Testing methods

Mohit Nitin Shenvi, Corina Sandu, Costin Untaroiu

Journal of Terramechanics, Volume 100, 2022, Pages 25-37, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.11.006.(https://www.sciencedirect.com/science/article/pii/S0022489821000896)

Abstract: Snow is a complex material that is difficult to characterize especially due to its high compressibility and temperature-sensitive nonlinear viscoelasticity. Snow mechanics has been intensively investigated by avalanche and army researchers for decades. However, fewer research studies were published for the compacted snow, defined as snow with a density in a range of 370–560 kg/m3. This review focuses on the various testing methods that are used especially to characterize the behavior of compacted snow under compressive and shear loading. The working principles, inherent assumptions, and advantages/disadvantages of the devices are summarized. In addition, some of the important material properties of snow like density, elastic modulus, etc., and their measurement is highlighted. Lastly, a correlation of the testing methods to commonly used approaches in modeling snow is presented. Overall, we believe that this study can help to better understand the existing test data related to compacted snow and guide future testing in this field.

Keywords: Compacted snow; Snow testing; Snow material properties; Snow material models

Tensegrital wheel for enhanced planetary surface mobility: Part 1 – Design and evolution

Georgia Crowther, Dimitrios (Dimi) Apostolopoulos, Stuart Heys

Journal of Terramechanics, Volume 100, 2022, Pages 11-24, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.11.008.(https://www.sciencedirect.com/science/article/pii/S0022489821000914)

Abstract: This paper follows ProtoInnovations’ development of a line of novel wheel concepts built with tensegrity principles for planetary mobility. The goal of these tensegrital wheels for enhanced planetary surface mobility is to exploit the geometric and mechanical attributes of tensegrity to mimic the compliant and load-distributing properties of a pneumatic tire using space-qualified methods and materials. In this paper we present our tensegrity design process and the evolution of our tensegrital wheel concepts. We conclude with an exploration of the tensegrital wheel’s potential with regards to planetary exploration applications and summarize considerations and improvements for future tensegrital wheel research.

Keywords: Tensegrity; Planetary mobility; Rovers; Wheel design; NASA

Fatigue integrity assessment for tractor-mounted garlic-onion harvester

Jeongwoo Han, Eungkyeong Kim, Sanggon Moon, Hanmin Lee, Jeonggil Kim, Youngjun Park

Journal of Terramechanics, Volume 100, 2022, Pages 1-10, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.11.005.(https://www.sciencedirect.com/science/article/pii/S0022489821000884)

Abstract: Tractor-mounted harvesters are operated under harsh conditions to dig deep-rooted crops on irregular soil conditions. Therefore, it is important to evaluate their fatigue strength by measuring random load characteristics that occur during operation. Based on this, highly reliable fatigue design that can be used safely without damage during the service life is required. In this study, the traction force of a tractor-mounted garlic-onion harvester was measured through a field test, and its fatigue damage was calculated based on the Rain-flow counting method and Goodman’s equation. In addition, a method of verifying the fatigue safety of the harvester by calculating the equivalent load and required test cycle for the accelerated life test in the laboratory was presented. The average traction force calculated from the torque history measured in field tests by attaching a torque meter to four tractor wheels at the actual harvesting site was found to be 8.51 kN. When the accelerated life test condition corresponding to the target life of 800 h was calculated using the presented method, the number of load cycles required under a maximum load of 12.37 kN and a minimum load of 7.56 kN was found to be 2.67 × 106 cycles.

Keywords: Tractor-mounted harvester; Fatigue integrity assessment; Field test; Fatigue damage; Accelerated life fatigue test

Tread rubber compound effect in winter tires: An experimental study

Mohit Nitin Shenvi, Adwait Verulkar, Corina Sandu, Hoda Mousavi

Journal of Terramechanics Volume 99, 2022, Pages 57-73, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.11.004.(https://www.sciencedirect.com/science/article/pii/S0022489821000872)

Abstract: This paper presents an indoor experimental study focused on analyzing the effect of various tread rubber compounds on the tire performance on ice. A set of sixteen tires (two per rubber compound) with identical dimensions, construction, and tread pattern, but of different tread rubber compounds, was investigated using the Terramechanics Rig which measures all forces and moments acting on a tire that is rolling (free or with slip) on ice. All operational parameters (normal load, inflation pressure, ice static coefficient of friction, ice temperature) were kept constant. Testing the tires under free rolling provided insights into the effect of the tread rubber compound on the resistive forces. The investigation led to conclusive evidence that the tread rubber compound affects drawbar pull coefficient significantly (double for best than for the worst tire). It was found that the effect of the tread rubber compound in the lower slip region is most prominent, which is also where vehicles operate most of the time. The decrease in the stiffness is generally considered a positive sign for improvement in available friction but this cannot be a generalized conclusion when analyzing the tire as a whole, which is one of the major findings of this study.

Keywords: Tire-ice; Winter tires; Tread rubber compound; Drawbar pull coefficient; Resistive forces; Genetic algorithm

Comparison of wheel load application methods in single-wheel testbeds

Adriana Daca, Amir Ali Forough Nassiraei, Dominique Tremblay, Krzysztof Skonieczny

Journal of Terramechanics, Volume 99, 2022, Pages 35-55, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2021.11.001.(https://www.sciencedirect.com/science/article/pii/S0022489821000847)

Abstract: This work reviews wheel load application methods in single-wheel testbeds (SWTBs), used widely to study terramechanics. Normal force oscillations have been reported in SWTBs, and visible in time-series data when provided. This has usually been attributed to grousers, but is also visible for wheels without grousers suggesting other system dynamics (e.g. friction in the vertical axis) are the cause. Furthermore, accelerations related to periodic vertical displacements of the wheel (whether caused by grousers or otherwise) cannot explain more than a small fraction of the amplitude of normal force variations. In this work, a 4-bar mechanism was developed that balances the normal load and ensures that a constant (not oscillating) normal force is achieved throughout terramechanics experiments. System behaviour with and without the 4-bar mechanism was assessed, highlighting the need for a 4-bar mechanism or other method of balancing normal loads if a constant normal force is desired. No significant effects on average experimental results were observed due to normal force oscillation, but artifacts were observed in the time-series data. Comparisons of results with a system where wheel load is applied pneumatically and characterization of friction in each testbed provide further support to the conclusion that normal force oscillations are mainly caused by friction in the vertical axis.

Keywords: Single-wheel testbeds; 4-bar mechanism; Wheel load; Normal force