1. ENT 353 Advanced Mechanical Design Dr. Haftirman /Shah Fenner Khan/Ahmad Yusri 1 ENT 353 ADVANCED MECHANICAL DESIGN Lecture 2. Fatigue of Metals 16/07/2007

2. ENT 353 Advanced Mechanical Design Dr. Haftirman /Shah Fenner Khan/Ahmad Yusri 2 Objectives To considered the analysis and design of parts subjected to variable loading. To describe how parts fail under variable loading and how to portion them to successfully resist such condition.

3. ENT 353 Advanced Mechanical Design Dr. Haftirman /Shah Fenner Khan/Ahmad Yusri 3 Variable Loading  Introduction to Fatigue in Metals Introduction to Fatigue in Metals  Strain-Life Relationships Strain-Life Relationships  Stress-Life Relationships Stress-Life Relationships  The endurance Limit The endurance Limit  Fatigue Strength  Endurance-Limit Modifying Factors Endurance-Limit Modifying Factors  Stress Concentration and Notch Sensitivity  Fluctuating Stresses Fluctuating Stresses  Failure Loci under Variable stresses Failure Loci under Variable stresses  Cumulative fatigue Damage Cumulative fatigue Damage  The Fracture-Mechanics Approach

4. ENT 353 Advanced Mechanical Design Dr. Haftirman /Shah Fenner Khan/Ahmad Yusri 4 Variable Loading  Static conditions => the specimen is tested to destruction, and so the stresses are applied only once. In most testing of those materials that relate to the stress- strain diagram. Static conditions

5. ENT 353 Advanced Mechanical Design Dr. Haftirman /Shah Fenner Khan/Ahmad Yusri 5 Variable Loading  Variable loading=> repeated, alternating, or fluctuating stresses