1. 3. Stresses in Machine Elements
Lecture Number – 3.2
Prof. Dr. C. S. Pathak
Department of Mechanical Engineering
Sinhgad College of Engineering, Pune
Strength of Materials

2. Agenda 1 Illustrative Numerical 1 Workout Example
Strength of Materials

3. Illustrative Example
The largest allowable stresses for the cast iron link are 30 MPa in tension and 90 MPa in compression. Determine the largest force P which can be applied to the link.
Strength of Materials

4. SOLUTION Determine an equivalent centric load and bending moment.
Superpose the stress due to a centric load and the stress due to bending.
Evaluate the critical loads for the allowable tensile and compressive stresses.
The largest allowable load is the smallest of the two critical loads.
Strength of Materials

5. Solution
Strength of Materials

6. Determine an equivalent centric and bending loads.
Strength of Materials

7. Superpose stresses due to centric and bending loads
Strength of Materials

8. Evaluate critical loads for allowable stresses.
The largest allowable load
Strength of Materials

9. Workout Example
For the beam and loading shown, determine the maximum normal stress due to bending.
Strength of Materials

10. SOLUTION
Treating the entire beam as a rigid body, determine the reaction forces
Section the beam at points near supports and load application points. Apply equilibrium analyses on resulting free-bodies to determine bending couples
Identify the maximum bending-moment.
Apply the elastic flexure formulas to determine the corresponding maximum normal stress.
Strength of Materials

11. SFD and BMD
Strength of Materials

12. Solution
Strength of Materials

13. I Section
A moment of 100 kN-m is applied to 2 m length beam of I section as shown in figure, find the maximum bending stress and draw the stress distribution diagram.
Strength of Materials

14. Solution
Strength of Materials