1 introduction to design skmm 1512 semester 2 session 2014/2015
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INTRODUCTION TO DESIGNSKMM 1512
Semester 2 Session 2014/2015
INTRODUCTION TO
DESIGNSKMM 1512
Week 2Engineering Design
MR. KHAIRUL ANWAR BIN HANAFIAHSenior Lecturer,
Applied Mechanics and Design Department
Faculty of Mechanical Engieering. UTM. Skudai.
Engineering Design
6 Fatigue Failure Resulting from Variable Loading
Chapter Outline
6-1 Introduction to Fatigue in Metals
6-2 Approach to Fatigue Failure in Analysis and Design
6-3 Fatigue-Life Methods
6-4 The Stress-Life Method
6-5 The Strain-Life Method
6-6 The Linear-Elastic Fracture Mechanics Method
6-7 The Endurance Limit
6-8 Fatigue Strength
6-9 Endurance Limit Modifying Factors
6-10 Stress Concentration and Notch Sensitivity
6-11 Characterizing Fluctuating Stresses
6-12 Fatigue Failure Criteria for Fluctuating Stress
6-13 Torsional Fatigue Strength under Fluctuating Stresses
6-14 Combinations of Loading Modes
6-15 Varying, Fluctuating Stresses; Cumulative Fatigue Damage
6-16 Surface Fatigue Strength
6-17 Stochastic Analysis
6-18 Road Maps and Important Design Equations for the Stress-Life Method
Introduction to Fatigue in Metals
• Static conditions : loads are applied gradually, to give sufficient time for the strain to fully develop.
• Variable conditions : stresses vary with time or fluctuate between different levels, also called repeated, alternating, or fluctuating stresses.
• When machine members are found to have failed under fluctuating stresses, the actual maximum stresses were well below the ultimate strength of the material, even below yielding strength.
• Since these failures are due to stresses repeating for a large number of times, they are called fatigue failures.
• When machine parts fails statically, the usually develop a very large deflection, thus visible warning can be observed in advance; a fatigue failure gives no warning!
END OF SLIDE
THANKS
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