Simulating Particle Breakage in DEM

Discover how particle breakage methods using the Discrete Element Method (DEM) enhance the realism of simulations for industrial applications.

The Importance of Accurate Particle Breakage Simulation

Accurate Particle Breakage Simulation is crucial in many industries such as mining, pharmaceuticals, construction, and food processing. The ability to simulate particle breakage accurately provides insights into how materials behave under mechanical stresses, leading to improved efficiency, product quality, and cost savings. There are some reasons for its importance:

• Optimizing Industrial Processes. It helps optimize processes like grinding, crushing, and milling by predicting how particles will break under specific conditions.

• Reducing Costs and Energy Consumption. Breakage simulations allow industries to fine-tune equipment settings to achieve desired outcomes with less energy consumption and fewer operational costs.

• Product Quality Improvement. In industries like pharmaceuticals and food processing, controlling particle size is essential for product quality.

• Safety and Equipment Longevity. Simulating particle breakage can also highlight potential equipment wear and tear.

• Design and Innovation. With reliable breakage simulations, engineers can explore new materials and methods without the need for costly, time-consuming physical testing.

Computational approach

The Discrete Element Method (DEM) is a numerical technique used to model the behavior of granular materials. It considers particles as discrete entities that interact through defined contact laws. The main principles of DEM include the representation of particle shapes, the calculation of contact forces, and the integration of Newton's equations of motion.

Ansys Rocky provides different options for predicting the comminution process for different granular materials, such as fibers, shells and solids with customed shapes. There is a white paper available for download (see the link at the end) that describes the approaches for simulating breakage, such as,

• Impact Energy model
• Ab-T10 breakage model
• Tavares breakage model
• Fragment size distribution models (Gaudin-Schumann and Incomplete beta function)

Drop Weight Test

The Drop Weight Test is a common method for assessing impact resistance and fracture toughness in materials. It involves dropping a weight onto a sample from a set height to mimic real-world impacts. This test measures energy absorption before material failure and provides data to calculate Ab and T10 parameters, which describe the material's breakage properties. A brieft description of both parameters is presented as follows:

• Ab parameter. The product of A and b is commonly used as an index to classify materials based on their impact breakage resistance. A lower Ab value indicates a tougher material that is harder to break, while a higher Ab value suggests a more brittle material.
  
  
• T10 parameter. Higher T10 values indicate a greater degree of breakage, meaning more fine material is produced from the impact. It is used to determine the material’s resistance to crack propagation, providing critical data for applications in industries like automotive, aerospace, and construction, where materials are subject to impacts.
  
  

Demo

The Drop Weight Test simulation is carried out in Ansys Rocky to demonstrate the setup of the Ab-T10 breakage parameters. By adjusting these values, future Rocky simulations can be calibrated. In this Demo, a 10 kg weight drops from a height of 30 cm to impact a 5.8 cm custom polyhedron particle, which then breaks into multiple fragments. The user can modify the input parameters as desired. 

Postprocessing includes the analysis of various data sets. The image below shows the Particle Size Distribution and percentage mass for each group (left), the drop weight’s position throughout the simulation (center), and its velocity (right). The velocity graph indicates the impact speed and moment of impact, while the final position of the drop weight reveals the presence of remaining particles after the test.  

Check out our video to see the full process of setting up and running the Drop Weight Test simulation in Ansys Rocky.