Discrete Element Simulation for the Behavior of Bulk Granular Material for Design Improvement
AMIT SRIVASTAVA
Discrete Element Simulation For The Behavior Of Bulk Granular Material For Design Improvement
Executive Summary
2
What Is DEM?
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How DEM Fares Better Than Traditional Methods
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Opportunities and Challenges
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The Bucket Design Experiment
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Leveraging DEM For Engineering Design Analysis For Excavation Buckets
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Results
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Future Scope For The DEM Technique
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References
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DEM or Discrete Element Method is a high-performance analytical solution for bulk and granular material simulation. The technique quickly and accurately simulates and analyzes the behavior of coal, mined ores, soils, fibers, grains, tablets, powders, and more. DEM simulation provides engineers and product designers with critical information about how materials interact with equipment during operations. Leading companies in the heavy equipment among several other sectors use the Discrete Element Method to assimilate and calculate granular material behaviors, evaluate equipment performance, and optimize processes. In this paper, we dive deep into the various aspects of DEM, as well as look into the bucket experiment to see how DEM enables better design for the heavy equipment sector.
Discrete element method (DEM), or the distinct element method, is a numerical method to compute motion and impact of large volume of particles. With improvements in computing power and algorithms, it has become possible to simulate particles on a single processor. Today, DEM is commonly acknowledged as an efficient and intuitive way to address engineering problems in granular materials, especially in granular flows, powder mechanics, and rock mechanics.
Granular particles are finite and discrete materials. Often, flowing particles behave like a continuum fluid. Conventional techniques such as finite element or finite–difference methods cannot appropriately simulate the discontinuous behavior exhibited by particles.The discrete element method (DEM) is a known numerical method that can model discrete particles like soil, sand, powder, grain, rocks among others. by tracking the motion and behavior of individual particles. DEM has been used extensively in the field of rock mechanics, powder, soil, and sand.Simulation of granular materials (soil, rocks, gravel) interaction with earthmoving machines provides opportunities to accelerate new equipment design and improve the efficiency of earthmoving machine performances. The Discrete Element Modelling (DEM) technique has the capability to model soil, powder, sand, and rocks for bulk behaviour due to the forces observed during the interaction with the component.
Heavy machinery product development and validation tests involve the interaction of equipment with granular particles such as soil, sand, clay, powder, and rock. The geomaterial environmental properties impact equipment performance in terms of efficiency, durability, and productivity. However, the iterative product development cycle of ”Design - Prototype build - Bench test” is heavy on time cost and labour. Virtual engineering tools have the potential to accelerate product design engineering and reduce field testing. Investigating the particle behaviour plays an important role during the NPD cycle and to improvise on the current design.With the DEM technique, granular particles of different shapes and sizes, with different environmental conditions can be modeled and simulated to understand the performance of the design under different environmental conditions. The technique also aids in identifying areas to focus for improving, changing, and optimizing the design.
Predicting the behavior of soil under different environmental conditions is a complex task.DEM, a particle-based modeling technique, has shown to be a proven research and development tool in manufacturing, agricultural, mining and process industry, where particles behaviour can be easily predicted. DEM can simulate the particles’ interaction with earth moving equipment. This makes it an ideal fit for engineering workflow in product design and performance. DEM can also address the cohesion and adhesion behavior of the soil during the interaction with equipment. With increase in computational power, efficiency, and robustness in computing, DEM has become a useful tool for a wide range of applications in mining and construction industries where different shapes, sizes of the particle can be used for simulation.But challenges remainThe key challenges in leveraging DEM arises from the difficulty in particle-based approximation of granular particles, terrain conditions, and its dynamic behaviour. Geomaterials have variations from terrain to terrain, environmental conditions (wet to dry), a wide range of particle sizes (clay to gravel size), and their response to loading.
Earthmoving machinery continuously interacts with granular particles like hard soil, soft soil, rocks etc. during operations. Bucket is the component that interacts with granular particles while digging operations. The design of the bucket therefore plays a vital role in improving digging efficiency.During excavation, the excavator bucket used in mining or construction interacts with the ground which could be soil, sand, rock, or mud among others. The bucket interacts with different conditions of ground. Therefore, efficient and durable design will help in improving its performance.The proposed solution on the bucket is focused on the design of the bucket. It is centered around improving digging efficiency, mass accumulation and prediction of wear and tear on the bucket surface during interaction with soil. It also predicts the performance of the bucket for various soil conditions such as loose, muddy, fine, etc.
DEM simulation workflows are not complex for simple geometry motion, particle shape close to spheres, and small number of particles. The DEM technique is also used for a wide range of engineering applications that require that the DEM be integrated into product development cycle and coupling with other methods such as Finite Element, Multibody Dynamics & Computational Fluid dynamics for systems modeling.DEM simulation workflow can be looked at as a component of system engineering. The proposed solution on bucket performance and digging efficiency captures the requirements from the application, simulation, and particle mechanics know-how to define shape and size approximation, calibrate particle model, and analyze the condition with reduced uncertainty and controlled variance for design.The following steps define the simulation workflow to validate the bucket design on performance efficiency.
1. Defining system requirement and setup. • Modeling of the soil
2. Material Model Calibration • Adhesion & Cohesion • Angle of Repose
Angle of Repose Calibration
3. Simulation • Soil-Bucket interaction • Design improvement areas
The technique should be demonstrated to various groups that can leverage it, such as process, medical, industrial machinery and others where particle flow plays an important role in the component design. DEM can be coupled with CFD to model or simulate systems combining fluids with solids or particles.Key industries where DEM can play a critical role include Agriculture and Food Handling, Chemical, Detergents, Oil & Gas, Mining, Mineral Processing, Pharmaceutical, and Powder Metallurgy among others.
https://doi.org/10.1063/5.0016448 “Study on track–soil traction using discrete element method simulation and soil bin test”Ebook applications of EDEM for Construction & Mining Equipment Design
