Introduction
It is not necessary to perform a finite element analysis of your component to generate an Adams Flex body. It is also possible to generate a flexible body in Adams from modal test data stored in a Universal file format. You can translate the Universal file into a Modal Neutral File (MNF) that you can use to create a flexible body with a constant coupling inertia invariant formulation. For more information on invariant formulations, see Modifying the Modal Formulation.
Learn more about:
Universal File Requirements
To create a modal neutral file (MNF) from modal test data, you must provide a single Universal file that contains:
■Nodal positions stored in Universal file dataset 15
■Element connectivity, or trace lines, stored in Universal file dataset 82
■Mode shapes and natural frequencies stored in Universal file block 55
Note: | Only the real, translational components of the mode shapes will be considered by Adams Flex. Consequently, the component will be infinitely stiff with respect to rotational deformations. |
Adams View supports Universal files exported from I-DEAS, CADAX, or STAR, which meet these requirements.
Units
The Universal file can be in any set of units that Adams View supports. Learn about Units of Measurement in Adams View.
Other Required Data
In addition to providing a Universal File containing the modal response of the component, you will also be required to provide the total mass and inertia of the component as well as the center of mass location.
Limitations
Because it is difficult to capture a component’s distribution of mass using experiment methods, the MNF will only contain inertia invariants describing the global inertia properties, namely invariants 1, 2, and 7. These three inertia invariants are all that is required for the constant coupling inertia invariant formulation. Consequently, an Adams Flex flexible body created from modal test data should exclusively use the constant coupling inertia invariant formulation.
Translating Universal File to MNF
To translate a Universal file using Adams View:
1. From the Ribbon menu, click the Bodies tab. From the Flexible Bodies container, click the Adams Flex tool 
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(Classic interface) From the Build menu, point to Flexible Bodies, and then select Adams Flex.
The Create a Flexible Body dialog box appears.
2. In the Universal File text box, enter the name of the Universal file containing datasets 15, 55, 82 and, in the option menu to the right, select the program from which it was generated (CADA-X, I-DEAS, STAR).
3. In the MNF File text box, enter the name of the MNF to be created. If you do not provide a file name, Adams Flex generates an MNF with the same path and prefix as the Universal file.
4. In the Total Mass text box, enter the global mass of the tested component.
5. In the Center of Mass text boxes, enter the x, y, and z coordinates of the tested component’s center of mass, relative to datum used to measure the nodal positions in dataset 15 of the Universal file.
6. In the Inertia Tensor text boxes, enter the inertia tensor of the tested component relative to the center of mass.
7. If desired, in the Title and Comments text boxes, enter a title for the MNF and any comments you want to identify it.
8. Set Length Units, Mass Units, Time Units, and Force Units to the units used in the Universal file and the data entered in this dialog box.
9. Select OK.
10. After successfully translating the Universal file to an MNF, return to the Create a Flexible Body dialog box to create your flexible body in Adams View.