Abaqus Mesh Algorithm

Description

There are many techniques for Abaqus mesh to increase element size for the far region to save time. Each is useful and we will cover them one by one in these series of videos.

The Abaqus Mesh Technique Tutorial Video

• The First Video:

This video explains an advanced Abaqus mesh technique that is very helpful to enhance computational time without losing model accuracy. The method is useful for 3D models with critical areas such as models with contact. This Abaqus mesh technique needs partitioning the face then using cell partitioning to divide the part into more components. Next, by using the sweep technique the element size will increase in X, Y, and Z directions. It is a very beneficial technique to use small element sizes for areas with a high-stress gradient and  larger elements for farther regions. To have a better understanding of the procedure, the sweep profile and sweep path are explained in a PowerPoint slide.

• The Second Video:

This video explains an advanced technique to mesh the components for enhancing the computational time without losing model accuracy. The method is useful for parts with holes in them. This technique needs partitioning the face then using cell partitioning to divide the part into more regions. Next, by using medial and axis and advancing front techniques the component will mesh separately. This approach is beneficial to mesh the components which require to have contact with pins and screws. To have a better understanding of the procedure, each algorithm technique in Abaqus for the sweep profile is explained in a PowerPoint slide. In the presentation file, three examples from Abaqus documentation are provided to show what types of algorithms are beneficial for different parts.

You can download the Abaqus CAE file which includes the parts, the assembly and the mesh. 

This video is made by Reza Tangestani. For more information, please send him an Email:

rezatangestani@hyperlyceum.com

You could also find the video on our youtube channel:

Abaqus Mesh Module

In the Abaqus Mesh module, there are various capabilities to mesh a part. Most of the time, especially in industrial projects, we are faced with complex solid geometries that must be meshed and then analyzed. One of the main steps in meshing a model in Abaqus is choosing the shape of the element and the technique of creating the mesh.

If you went to the Mesh controls option in the Abaqus Mesh module, you must have noticed the technique tools on the left side of the menu.

Four important types are:

1. Structured
2. Sweep
3. Free
4. Bottom-Up

Structured Abaqus Meshing

All three of these methods perform networking automatically, and each has its strengths and weaknesses. If you are looking for the best technique, we suggest you use the Structured mode because you have the most control over the elements in this mode. Structured meshing applies pre-established mesh patterns to particular model topologies. Complex models must generally be partitioned into simpler regions for this technique. About the rest of them, we will talk later. Before talking about the video we are going to explain a few details:

Aspect Ratio Tool

Abaqus/CAE shows you any bad elements in the mesh by highlighting them after completing the mesh. Abaqus/CAE also lets you verify the quality of your mesh. You can gather information about the nodes and elements in the mesh with a set of tools in mesh modules. You can use these tools to isolate regions where the mesh quality is poor. It also guides you if you need to refine your mesh. From the main menu bar select MeshVerify, then choose the Object from the context bar to verify the quality of the mesh. Then, you can select the part, part instances, geometric regions, or elements to verify.

You can also verify the elements individually or from a region with single or multiple factors, such as checking for elements with a large aspect ratio. The aspect ratio must be less than 10 or at most 20 for a satisfactorily accurate calculation. If there is a highlighted element, it means the aspect ratio is larger than the selected value and needs to be fixed. For detailed information on using mesh verify tools.

Edit mesh tool

To edit the elements you can use the drag tool on a meshed part, for instance an orphan mesh. It helps to improve the element quality simply by clicking. When you activate the node dragging function, Abaqus/CAE automatically activates the solver element quality checks and highlights the elements based on the error. The highlighting is updated as you drag a node into a new position; therefore, you can immediately see whether you are improving the element quality. You cannot use the Edit Mesh tools to modify the mesh of a dependent part instance; but, you can drag the nodes of a dependent part instance. To use the tool you can do the following steps:

1. In the Category field, select Node.
2. From the Method list, select Drag.

Abaqus/CAE displays the existing nodes.

Importance of Element Size in Abaqus

The element size is a key factor in large simulations because doubling element size can lead to the reduction of computational time to 1/8 for standard models. This ratio will be larger for explicit models as it affects the incerement time as well. To learn more you can watch this series of videos about explicit models.

When it comes to biomechanical models the story is different. Since the geometries are complex it is very important to define very exact element sizes for contact regions. For the contact areas, we need to make sure we are using the right ratio for the master and slave elements. Otherwise, we will face errors as was explained in this video:

In case you would like to know more about Abaqus!

Abaqus is an FEA software for multiple engineering purposes. It has been widely used by many researchers, companies, and students to simulate simple and complex models. Abaqus is a flexible tool to analyze processes compared to other software. Even though it has a user-friendly environment, it is not easy to learn as the license is extremely expensive. Therefore, tutorial videos on this software are not easy to find or are too expensive. Before explaining the Abaqus tutorial details, we should first learn what Abaqus covers and what exactly it is. The following explanation was extracted from Abaqus 6.14 documentation.

Abaqus/CAE  is a Complete Abaqus Environment that provides a simple, consistent interface for creating, submitting, monitoring, and evaluating results from Abaqus simulations. Abaqus/CAE is divided into modules, where each module defines a logical aspect of the modelling process; for example, defining the geometry, defining material properties, generating a mesh, submitting analysis jobs, and interpreting results.