Discover the Hypermesh Aerospace Ribbon Part 1: Compare models

Nathan_G · November 26

Introduction:

The aerospace ribbon in Hypermesh offers a collection of tools developed by the aerospace field team to solve specific challenges faced in the aerospace field. However, it is available and useful for users in any field. This series of posts will document the capabilities of those tools and provide sample models to try them out yourself.

Please note: These tools were written by Altair field support engineers. These functions are not tested and verified by the standard Altair software development process. However, the authors tested these functions and verified them for their customer's needs. Software groups will migrate these tools to core functions for future releases. Until then, the stability and performance of these functions is not guaranteed.

The Compare Models tool:

Found in the aerospace ribbon-> Assembly tools-> Compare models, this tool's purpose is to load and compare key attributes between two different input decks. It is available in the Optistruct and Nastran interfaces only, and accepts exactly 2 .FEM files as input. The basic workflow is shown in the diagram below.

There are 3 main types of comparison available:

Global

When a global comparison is made, the following model information is compared: Node count & ID range, Element count & ID range, RBE2 count & ID range, RBE3 count & ID range, MPC count & ID range, Properties count, Materials count, mass, X-CG, Y-CG, and Z-CG.

The values of each attribute for each input deck is reported along with the difference detected (if any).

Local- Nodes

When a local nodes comparison is made, the following information is compared: X-Coordinate, Y-Coordinate, Z-Coordinate, Magnitude.

The user has the responsibility to select which nodes to compare via the select entities panel, and the option of whether to select from the main or secondary model. A difference tolerance filter is also offered, or the user can select "none" to see attribute values on the entire selection.

Attribute values, differences, percentage difference, and ratio can be exported and plotted on the model with the buttons on the bottom of the Compare models dialogue.

Local- Elements

When a local elements comparison is made, a variety of element attributes are available for comparison shown below

Similar to a comparison on nodes, the user has the responsibility to select which elements to compare via the select entities panel, and the option of whether to select from the main or secondary model. A difference tolerance filter is also offered, or the user can select "none" to see attribute values on the entire selection.

Attribute values, differences, percentage difference, and ratio can be exported and plotted on the model with the buttons on the bottom of the Compare models dialogue.

Example Comparison:

The attached solver decks have been modified with the changes shown. Try using the compare tool to uncover the differences between the files

wing_modified.fem

wing_nominal.fem