Understanding Stress Concentration in Mechanical Elements

Stress concentration in mechanical elements occurs due to sudden changes in cross-section, leading to negative effects such as decreased strength and crack initiation. Factors affecting stress raisers include the value and type of load, as well as the dimensions and shape of the stress raiser. Different shapes like single V-notch, single sharp-edge notch, curved shoulder, and double notch have varying effects on stress concentration. Examples of failed elements include fatigue failure of a shaft and pitting corrosion on an aluminum housing due to elevated temperatures.

• Stress Concentration
• Mechanical Elements
• Load Type
• Stress Raisers
• Failure

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2. PART I STRESS CONCENTRATION

3. 1. Stress concentration Stress mechanical elements due to sudden change in cross section. concentration appears in It has negative effects: - Decrease the strength of element. - Tends to crack initiation. Dimensions of stress raiser.

4. It is affected by: - Value of load. - Type of load. - Dimensions & shape of stress raiser.

5. Shape of Stress Raisers Single V- notch Single Sharp- edge Notch

6. Curved shoulder Single Semi-circular Notch

7. Effect of Double notch Shape

8. Effect of Combined stress (Load Type)

9. 1. Shoulder

10. 2. Single Sharp-edge Notch

11. 3. Single V-shape Notch

12. 4. Single Semi-circular Notch

13. 5. Double V-shape Notch

14. 6. Double Sharp-edge Notches

15. 7. Double Semi-circular Notch

16. 7. Examples of Failed Elements Fatigue failure of a shaft

17. Pitting corrosion resulting from elevated temperatures on an aluminum housing.

18. A brittle fracture that originated at a surface defect.

19. Three conveyor rollers: The center one is as supplied, The outer two have failed from contact stresses. The left roller was case hardened and cracked. The right roller was unhardened and ductilly deformed.

20. Fracture due to Torsional effect.

21. Keyseat distortion Torsional force Keyway deformation due to shaft overloaded.

22. Ductile deformation due to shaft overloaded.