flex translate modal

7/27/2019 Flex Translate Modal

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1Translating Modal Test Data

Translating Modal Test Data


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Adams/FlexIntroduction

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IntroductionIt 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 Format Requirements

Translating Universal File to MNF

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

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 components 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

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.
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3Translating Modal Test DataIntroduction

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 fi le using Adams/View:

1. From the Build menu, point to Flexible Bodies, and then select Adams/Flex.

The Create a Flexible Bodydialog box appears.

2. Select FEM translate.

3. From the option menu in the upper left corner, select Test Modal.

4. 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).

5. 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.

6. In the Total Mass text box, enter the global mass of the tested component.

7. In the Center of Mass text boxes, enter the x, y, and z coordinates of the tested components

center of mass, relative to datum used to measure the nodal positions in dataset 15 of the Universal

file.

8. In the Inertia Tensor text boxes, enter the inertia tensor of the tested component relative to the

center of mass.

9. If desired, in the Title andComments text boxes, enter a title for the MNF and any comments

you want to identify it.

10. Set Length Units, Mass Units, Time Units, andForce Units to the units used in the Universal

file and the data entered in this dialog box.

11. Select OK.

12. 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.
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