How to Calculate Fatigue Strength for Machine Design

TL;DR

To calculate the fatigue strength of a rotating bar for 90,000 cycles, plot the SN curve using logarithmic values of the number of cycles and the endurance limit. Interpolate the curve to find the desired strength, which is determined to be approximately 386.63 Newton per millimeter square for the specified conditions.

Transcript

click the Bell icon to get latest videos from akira hello friends welcome back to the subject of machine design 1 we are right now learning about various design procedures considering the fluctuating and reverse loadings in last session we have seen numerical based on the infinite life criteria in today's session we are going to look at a numerical... Read More

Key Insights

• 🎰 The calculation of fatigue strength for machine design requires considering bending stress and endurance limit.
• 🏍️ The SN curve is useful in determining the required strength for a specific number of cycles.
• 📶 Interpolation is used to find the desired strength value from the SN curve.

Questions & Answers

Q: What is the objective of the video?

The video aims to explain how to calculate the fatigue strength for a rotating bar under completely reverse bending stress.

Q: How is the SN curve used in this calculation?

The SN curve, plotted using logarithmic values, helps determine the required strength value for a specific number of cycles.

Q: What is the significance of the interpolated value?

The interpolated value provides the desired strength of the product after 90,000 cycles by finding the corresponding point on the SN curve.

Q: Can you explain the process of finding the fatigue strength in more detail?

The video walks through the steps of finding the logarithmic values, plotting the SN curve, interpolating the desired strength, and converting it back to its actual value.

Summary & Key Takeaways

• The problem involves calculating the fatigue strength of a rotating bar for 90,000 cycles based on the SN curve.

• The SN curve is plotted using logarithmic values of the number of cycles and endurance limit.

• The fatigue strength is determined by interpolating the desired strength value from the SN curve.