“My geometry is simulation-ready, and I don’t need any clean-up.”

‍You’ve likely heard this phrase, or used it yourself, to meet tight deadlines and streamline collaboration with teams that rely heavily on simulation results.

Unfortunately, the group most affected by this so-called “shortcut” is almost always the simulation team.

Based on the experience of Designfusion engineers, underlying geometric issues such as gaps, intersecting surfaces, holes, and non-manifold edges are often the true culprits. Even with ideal discretization settings, these defects can cause simulations to fail. Designfusion provides engineering resources specifically to tackle these problems.

Let’s consider a Linear Static Analysis of the aircraft model shown below.

Debunking the “Myth”

Saying that this model is simulation-ready would be a myth. Our team closely examined the model and found:

1. Duplicate surfaces

2. Intersecting surfaces

3. Holes

If this model were discretized as-is and used for simulation, errors would be unavoidable. And that’s where the real challenges begin.

Sequential Error-Checking Workflow

Simulation debugging typically starts with the boundary conditions. If they appear correct, the next step is mesh verification. At this stage, mesh repair often involves resolving errors like:

1. Non-manifold edges

2. Free edges

3. Slivers

4. Duplicate surfaces

This debugging stage can consume a significant amount of project time. Designfusion can supplement your engineering team to help you catch up and stay on schedule by cleaning and preparing the geometry for mesh generation. A clean model improves the quality of the mesh before running a stable and predictable simulation. It is mandatory to examine the geometry. This step not only informs the modeling strategy but also helps identify the root cause of errors that appear later in the simulation process.

The most important question in CAD clean-up is what should be removed and what should be retained. Features such as fillets, chamfers, and holes that do not support or interface with adjacent components should typically be removed. Sometimes, faces are divided or combined to ensure proper mesh flow and achieve a coincident mesh.

Approach to Preparing a Meshable Model

In the above aircraft example, the simulation's goal is to evaluate the fuselage's behavior. Our team followed this approach:

1. Repaired the duplicate and small sliver surfaces on the model.

2. Some component structures were removed, such as the fuselage antenna, and replaced with a point mass as a modeling strategy.

3. The landing gear assembly was excluded from the scope of the simulation.

4. Only one side of the model was cleaned due to longitudinal symmetry, then mirrored to create the complete, clear, and meshable model.

The final simulation-ready model is shown below.

To prepare this model, the team at Designfusion used Altair Hypermesh, which is now part of the Siemens Digital Engineering product portfolio.

At Designfusion, we harness the power of CAD and simulation to deliver cutting-edge engineering solutions that meet the highest standards of precision and innovation. By leveraging advanced simulation capabilities alongside our design expertise, we turn visionary concepts into 3D models, driving excellence in every project we undertake.

Get in touch and see how we can help you today.