Discrete element method (DEM) has become a preeminent numerical tool for investigating the mechanical behavior of granular soils. However, traditional DEM uses sphere clusters to approximate realistic particles, which is computationally demanding when simulating many particles. This paper demonstrates the potential of using a physics engine technique to simulate realistic particles. The physics engines are originally developed for video games for simulating physical and mechanical processes that occur in the real world to produce realistic game experiences. The simulation accuracy and efficiency of physics engines have been significantly improved in the last two decades allowing them to be used as a scientific tool in many disciplines. This paper introduces modeling methodologies of physics engine including realistic particle representation and the contact model. Then, oedometer tests are simulated using realistic particles scanned by X‐ray computed tomography (X‐ray CT). The simulation results agree well with experimental results. This paper demonstrates that physics engines can output contact parameters for geotechnical analysis and force chains for visualization.
Simulation of realistic granular soils in triaxial test using physics engine
The discrete element method (DEM) is the most widely applied numerical tool to simulate triaxial test, a common geotechnical test to measure the shear strength of soil. However, the typical DEM model uses sphere clusters to approximate soil particles, which is not sufficiently accurate to simulate realistic soil particles. This paper shows the potential of using a physics engine technique as a promising alternative to typical DEM method. Originally developed for simulating realistic physical and mechanical processes in video games and computer-animated films, physics engines have developed quickly and are being applied in scientific computing. Physics engines use triangular face tesselations to represent realistic objectives, which provides higher accuracy to model realistic soil particle geometries. In this paper, physics engine is applied to simulate true triaxial
tests ofMonterey No. 0 sand. The numerical results agree well with experimental results. This study provides DEM modelers with the physics engine technique as another promising option to simulate realistic soil particles in geotechnical tests.
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- Award ID(s):
- 1917332
- PAR ID:
- 10462326
- Date Published:
- Journal Name:
- Computational Particle Mechanics
- ISSN:
- 2196-4378
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary -
Hambleton, J. P. (Ed.)Discrete element method (DEM) has been widely applied to simulate granular soil behavior. However, traditional DEM uses sphere clusters to approximate realistic particles, which is computationally demanding when simulating many particles. This study explores the use of physics engine, a platform developed for simulating physical processes in video games, to simulate realistic particles. This paper compares realistic particle simulation methodologies using physics engine and discrete element method, including contact models, parameter settings, computational speeds, and simulation results. The results show that the physics engine and DEM achieve similar simulation outputs, while the physics engine runs significantly faster than DEM, because PhysX uses both CPUs (central processing units) and GPUs (graphics processing units) of computers, triangular face tessellations to represent realistic particles, and a simplified contact model to accelerate simulations. This study provides geo-mechanicians and DEM modelers with one more option for them to consider when they simulate realistic particles.more » « less
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We report on an open-source, publicly available C++ software module called Chrono::GPU, which uses the Discrete Element Method (DEM) to simulate large granular systems on Graphics Processing Unit (GPU) cards. The solver supports the integration of granular material with geometries defined by triangle meshes, as well as co-simulation with the multi-physics simulation engine Chrono. Chrono::GPU adopts a smooth contact formulation and implements various common contact force models, such as the Hertzian model for normal force and the Mindlin friction force model, which takes into account the history of tangential displacement, rolling frictional torques, and cohesion. We report on the code structure and highlight its use of mixed data types for reducing the memory footprint and increasing simulation speed. We discuss several validation tests (wave propagation, rotating drum, direct shear test, crater test) that compare the simulation results against experimental data or results reported in the literature. In another benchmark test, we demonstrate linear scaling with a problem size up to the GPU memory capacity; specifically, for systems with 130 million DEM elements. The simulation infrastructure is demonstrated in conjunction with simulations of the NASA Curiosity rover, which is currently active on Mars.more » « less
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This paper presents the results of soil characterization and element tests of Ottawa F65 sand. The data presented is intended to be used as calibration material for the prediction exercise conducted as part of the Liquefaction Experiments and Analysis Project (LEAP 2017). The databank generated includes soil specific gravity tests, particle size analysis, hydraulic conductivity tests, maximum and minimum void ratio tests, and cyclic triaxial stress-controlled tests. An effort was made to ensure the consistency and repeatability of the test results by reducing the sources of variability in the sample preparations and increasing the number of tests. The uniformity of the soil was evaluated by conducting tests on samples from five different batches. The results showed that the sand is uniform among the five batches. Due to significant variability in previously reported maximum and minimum void ratio results, the effects of the test operator were studied by comparing test results obtained from three different operators. For the triaxial tests, a constant height dry pluviation method was used for sample preparation. To eliminate the effect of the human error in maintaining a constant drop height and to ensure consistency of the sand fabric between different samples, a device was developed to facilitate the sample preparation. The cyclic triaxial experiments were performed using three different soil densities, and a liquefaction strength curve was obtained for each density based on a 2.5% single amplitude axial strain criteria. The developed databank in this study was made publicly available for the community through DesignSafe.more » « less
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This paper proposes a numerical framework to model the deployment of a Free Fall Penetrometer (FFP) device in dry sands using the Material Point Method (MPM). Seabed characterization is required to assess a number of geotechnical problems in the nearshore and offshore areas, and FFP deployment is becoming a popular method to characterize shallow sediments. A moving mesh technique is used to ensure the accurate geometry of the FFP device throughout the calculation and the soil-FFP interaction is modelled with a frictional contact algorithm. The FFP device is simulated as a rigid body, which enhances the performance of the computation and reduces its computational cost. Numerical results are compared to experimental data, and are very promising.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s40571-023-00637-3
