Carnegie Mellon University
Mechanical Engineering

Problem 2 : Simply Supported Beam Under 4 Point Bending




1. Specify Geometry

Click on the following in the drop down menu on your right.


PREPROCESSOR -> -Modeling - Create

      CREATE -> -Areas -Rectangle

            RECTANGLES -> By Dimensions...

CREATE RECTANGLE BY DIMENSIONS -> A box should appear asking for x and y coordinates.The beam you wish to model is 24 inches long, 2 inches high and 1 inch into the screen. Since this example can be modeled as a plane stress problem, it is easier to draw the beam as a two dimensional area instead of a volume. If not specified otherwise, ANSYS assumes a thickness of 1 into the screen. Enter the appropriate dimensions in inches. Make sure the information you have entered is valid and then click OK. (DO NOT click Apply and then OK. This will place two rectangles in that location!)

In general, if the situation you are trying to model lends itself to a constant stress(or temperature,etc.) in the z direction (into the screen) then it should be drawn as an area instead of a volume. This cuts down on the memory used and time required for calculations. If a 3-D model is required, then all you have to do is choose the appropriate volume from the CREATE menu and proceed from there.

In this problem, you will enter all dimensions in inches, forces in pounds and moduli in pounds/in^2. By doing this your stress results will be in pound/in^2. ANSYS does not keep track of units, so it is essential that you enter data using consistent units. For an SI unit system, dimensions should be entered in meters, loads in Newtons, and moduli in N/m^2 or Pa. This will result in stress output in Newtons.

A light blue rectangular area should appear on the screen.





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