Discrete Element Modeling in Abaqus

DEM simulation of a spud can penetrating a seabed with dynamic rock fill

Simulating Granular Particle Behavior With Abaqus/Explicit

Granular materials, such as rock fill, shot peening media, or pharmaceutical granules, don’t  behave like typical solids. Their bulk response isn’t governed by internal deformation, but by frictional contact and motion between rigid particles. For these cases, the Discrete Element Method (DEM) in Abaqus/Explicit offers a purpose-built approach to model the physics of granular systems with high fidelity. 

Unlike continuum methods, DEM treats each particle as an independent object, allowing engineers to simulate contact-driven behavior, particle settling, flow, and jamming in a way that aligns with real-world mechanics. 

How DEM Works in Abaqus 

In Abaqus, DEM particles are modeled as rigid spheres, represented by single-noded elements. Each particle has translational and rotational degrees of freedom, with rotation playing a key role in capturing frictional effects during contact. Internal deformation is not modeled; all mechanical behavior results from interactions between particles and with other surfaces. 

Contact is handled using general contact. By default, Abaqus applies a penalty-based method, which introduces compliance between particles and allows macroscopic stiffness to emerge from the particle system. Alternatively, engineers can select a Hertzian contact law to simulate nonlinear force-displacement behavior and improve timestep stability. 

DEM also supports particle generation during the simulation. This allows for dynamic filling processes, where particles are introduced over time with sizes drawn from a specified probability distribution. For scenarios that require more complex shapes, Abaqus allows clustering of multiple DEM particles using MPC constraints. However, clusters must be predefined, particle generation and clustering cannot be combined. 

A few key features of DEM in Abaqus include: 

• Contact Modeling: Choose between penalty-based and Hertzian contact for stiffness and timestep control. 

• Particle Creation: Use predefined particles or dynamically generate them during the analysis. 

• Shape Representation: Approximate complex geometries by combining spheres into clusters using MPCs (not compatible with generators). 

Compared to Smoothed Particle Hydrodynamics (SPH), another particle-based method in Abaqus, DEM is simpler and better suited when deformation within the particles themselves is negligible. 

Example: Seabed Penetration With Rock Fill

A practical example of DEM in action involves simulating a spud can being pushed into a seabed while granular rock fill is deposited from above. In this case, 100,000 DEM particles were generated during the simulation, each assigned a radius from a normal distribution to reflect natural size variation. 

The setup also included several hundred rigid 3D cross-shaped bodies to add geometric complexity and increase the diversity of contact interactions. To improve timestep control, Hertzian contact was used for all DEM interactions. The motion of the spud can was delayed using an amplitude definition, allowing the rock fill to settle before contact occurred. 

This simulation effectively captured large-scale particle behavior, demonstrated how DEM handles nonlinear contact, and showed how to manage dynamic filling and interaction with rigid structures. 

Best Practices for Using DEM in Abaqus 

1. Use Hertzian contact when simulating large numbers of particles to stabilize time increments and reduce computation time. 

2. Delay rigid body motion (e.g., pressing tools, spud cans) until particles settle to avoid dynamic instabilities. 

3. Avoid combining clusters with particle generators, as MPC-constrained clusters only work for predefined particles. 

4. Define particle size and density carefully to reflect realistic packing behavior and achieve accurate bulk stiffness. 

5. Monitor timestep performance, especially in dense systems, adjust contact stiffness and damping parameters if the simulation becomes inefficient. 

Apply DEM to Your Particle Simulations With Confidence 

4RealSim helps engineers model complex granular systems using DEM in Abaqus. Whether you're working with industrial filling, powder compaction, or high-resolution contact simulations, we can assist in setting up and validating your models for reliable, efficient results. 

Need Help With DEM in Abaqus

Modeling granular materials like rock fill, powders, or pellets requires a different approach than traditional FEA. Our team at 4RealSim is ready to help you implement DEM simulations efficiently and accurately. From choosing the right contact model to optimizing particle generation, we provide expert support tailored to your application. Reach out through our contact form or email us at sales@4realsim.com for assistance with your DEM projects.