Machine Design II (ME 308 Lab)

(Project 2 - Term 022)

Determination of Shaft Diameters using Static & Fatigue Analyses

Static Analysis

Use the following D.E.T. equation:

1.    Diameter D1 – no static analysis needed – assume based upon diameter of D2 at about 0.7~0.8 times D2

2.    Diameter D2 - perform static analysis – high moment and max. torque

3.    Diameter D3 – perform static analysis – high moment and max. torque

4.    Diameter D4 - perform static analysis – max. moment and max. torque

5.    Diameter D5 - perform static analysis – high/moderate moment and max. torque

6.    Diameter D6 - perform static analysis – negligible moment but max. torque

Fatigue Analysis

¨     First identify all the critical locations where fatigue analyses would be necessary

¨     Critical locations are locations on the shaft where there is a combination of stress concentration with a high bending moment

¨     Stress concentration locations are those locations where abrupt changes in the cross-sectional area (case 1) occur or where there is a non-uniformity in the cross-section (case 2)

Use the following D.E.T. equation:

1.    Diameter D1 at fillet – ignore fatigue analysis – case 1, but low moment

2.    Diameter D2 on keyway – perform fatigue analysis – case 2 and high moment

3.    Diameter D2 at fillet - perform fatigue analysis – case 1 and high moment

4.    Diameter D3  - no fatigue – no stress concentration though moment is maximum

5.    Diameter D4 at fillet - perform fatigue analysis – case 1 and high moment

6.    Diameter D5 at fillet - perform fatigue analysis – case 1 and high moment

7.    Diameter D6 at fillet – ignore/check fatigue analysis – case 1, but low moment

8.    Diameter D6 on keyway – ignore fatigue analysis – case 2, but low moment