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