Creep Rate, Fatigue Life Methods, Endurance Limit, and Stress Concentration

Fatigue Life Methods

Where all symbols have their standard meaning, A and n can be found from creep rate.

1. The initial tightening stress in the bolts in order that a safety factor of 1.6 is maintained after 8000hrs of creep relaxation at 500? C.

2. The time when the bolts should be re-tightened to prevent leakage around the plate.

1. Explain the three major fatigue life methods and their benefit and limitations.

2. Discuss endurance limit with practical examples, also include endurance limit modifying factors.

3. Briefly explain with examples the meaning of stress concentration and notch sensitivity.

The reverse stress fatigue limit for low-carbon steel is ±270 MPa, its Ultimate

Tensile Strength, UTS is 670 MPa and its yield stress is 260 MPa.

1. Estimate the safe range of stress for a repeated cycle based on the Gerber and Goodman fatigue predictions.

2. Determine the peak stresses and safe range of stress for an alternating tensile cycle with mean stress 185 MPa based upon the Soderberg prediction

• The report should be concisely written with clear steps.

• The report presentation constitutes 10% of this coursework, 5% for each section. Appropriate referencing should be used where necessary.

• This course work assignment should be submitted online, on or before 22 November 2019