7/13/2011

Free Vibration Analysis

Workshop 5.1 - Goals

Our goal is to investigate the vibration characteristics of a motor cover manufactured from 18 gage steel. The cover is to be fastened to a device operating at 1000 Hz.

Workshop 5.1 - Assumptions

-The cover is meant to slip over a cylinder and be constrained at the bolt hole locations. To simulate the area contacting the cylinder the surface has been split (see below). We will use a frictionless support on this surface to simulate the contact area. The frictionless support type applies a constraint that is normal to the surface, thus axial and tangential movement is allowed while radial motion is not.

-To simulate the bolted connections a fixed support type will be used on the edges of the bolt holes.

Workshop 5.1–Project Schematic

Open the Project page.

From the “Units” menu verify:

-Project units are set to “US Customary (lbm, in, s, F, A, lbf, V).

-“Display Values in Project Units” is checked (on).

1.From the Toolbox double click “Modal” to create a new system.

2.RMB the “Geometry” cell and browse to “Motor_cover_5.x_t”.

3.Double click “Model” to open the Mechanical application.

Workshop 5.1 - Setup

4.Set the working Unit System:

-Units > U.S Customary (in, lbm, lbf, °F, s, V, A)

5.Rename the Model:

-RMB Model branch > Rename > “5 Hole Cover”.

Workshop 5.1 - Preprocessing

Since the model consists of surface geometry the parts will be meshed with shell elements. Surface geometry requires input for thickness in the details.

6.Specify Part thickness:

a.Highlight the “Part 1” branch.

Note : The “Thickness” field is currently displayed in yellow to indicate it is undefined. Also, the Part has a question mark next to it which means that it is not fully defined

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