The Evaluation of the Parallel Bond’s Properties in DEM Modeling of Soils

Abstract

In this study we conducted the sensitivity analysis of the parallel bond used in the discrete element method (DEM, 3D) IntroductionIt is important for the developing engineers of tillage machines to get fast and accurate feedback on the functionality and effectiveness of new constructions, because of the evolved market competition and the increasing needs of users. We can reconstruct field measurements by the investigations conducted in simulated environments. To investigate the micro-and macro cracks appearing in soils we need to use discrete element methods (DEM), instead of using continuous material models (FEM). Nowadays, because of the development of computer science, the DEM method is the most promising approach for modeling the soil-tool (sweep) interaction.In case of the soil-tool dynamic connection the cracks appearing in the soil affect greatly the size of the emerging deformation zone in front of the tool and thus the tool's towing resistance.It is hard to set the mechanical parameters of the "synthetic" materials used by the DEM method so as they are almost the same as the mechanical parameters of real materials [2]. Whereas the input parameters of continuum material models can be given directly from the results of laboratory measurements (Young's modulus, Poisson ratio, stress, etc.), the macro parameters of the material used in case of the DEM model depend on the features of the micro particles' connections. The input parameters in the DEM model are the parameters of the microscopic particles' connections (for example the spring stiffness between two particles, friction factor, etc.), that is why it is important to calibrate our model with the micro parameters. The parallel bond contact model was used to describe the liquid bridges between the soil particles and to set the so-called capillary effect in the model. The use of the parallel bond contact model enables the realistic cohesion in the DEM model.The micro parameters of the particle connections k k k k

Simplified DEM-Based Modelling and Simulation of the Track Ballast

“…𝑃𝐵𝑁 and 𝑃𝐵𝑆, parameters that determine the elasticity of the bond through the cylinder formed between adjacent particles, were bonded at 100 MPa and 0.4, respectively. These parameters were determined to demonstrate required stiffness as reported by Kornél Tamás et al [22]. In addition, the variable 𝑆𝐹𝐴 for the circular cross-sectional area was observed to be 1.5 for necessary stiffness and load transfer for the connection between particles with different radii.…”

Simplified DEM-based Modelling and Simulation of the Track ballast

“…𝐵𝑁 and 𝐵𝑆, parameters that determine the elasticity of the bond through the cylinder formed between adjacent particles, were bonded at 100 𝑀 𝑎 and 0.4, respectively. These parameter were determined to demonstrate required stiffness as reported by Kornél Tamás et al 19 In addition, the variable 𝑆𝐹𝐴 for the circular cross-sectional area was observed to be 1.5 for necessary stiffness and load transfer for the connection between particles with different radii. As shown in Figure 6c, an initial vertical displacement of 0.1 mm occurred between the sleeper bottom surface and the gravel.…”

Analysis of the Existing Numerical Methods for Modeling the Interaction of the Working Bodies of Digging and Soil-Processing Machines With Soil Media

“…Полученные результаты тягового сопротивления сравнивались с получаемыми аналитическим методом и с реальными испытаниями в почвенном канале. В Рисунок 6 -Моделирование взаимодействия с почвой стрельчатой лапы методом CFD сравнении с работами [18,19] результаты были на 5-10 % менее точными, чем при использовании DEM, но потребовалось на порядок меньше вычислительных ресурсов и времени. По сравнению с DEM настройка и запуск симуляции занимает гораздо меньше времени благодаря среде ANSYS и алгоритмам SPH, поскольку мы можем использовать хорошо известные встроенные модели материалов.…”