Roller bearing running on a shaft

In the analysis settings, under “General options” tab and then under the “Bearing Advanced” tab, you will find that “use ‘Enhanced contact analysis’” is turned on. Romax will use the shaft material properties in determining the allowable yield stress because the shaft is the bearing inner race in this case.

The allowable yield stress is calculated from the shaft material’s UCS (ultimate compressive strength) multiplied by the value show for “Factor to determine yield threshold from ultimate compressive strength” (the default value is 1.785714285714) to determine the yield point of the shaft.

To achieve a yield point of 4000 MPa, the UCS would need to be 2240 MPa (2240 x 1.785714285714 = 4000) for the shaft material. You can make a new material (copy of the material you are using for the shaft but with the higher UCS) in the database and then specify that material be used for the shaft section(s) supporting the rollers. This represents the hardening of the shaft to properly support the rollers running directly on the shaft.

For reference, the hardness of the shaft surface is usually required to be around Rc 62 by the bearing manufacturer so you should check to determine what they require for hardness and case depth of the shaft to properly support the bearing.