Saturday, February 15, 2014

Safety First: How to calculate the Factor of Safety

In Mechanical Design there is a very important concept that allows engineers to design safe components. It literally saves your life every time you take a flight, cross a bridge or climb a mountain.


Beto is relaxed because he knows that his climbing equipment is safe

It's known as the Factor of Safety and it's defined as follows:

where:
  • FS: Factor of Safety
  • Strength: Mechanical Strength of the component (in stress units)
  • Stressmax: Maximum stress allowed in the component
The objective of this formula is to find Stressmax. This is the stress that shouldn't be surpassed in your design.

In order to find Stressmax you need to know the other two variables:
  • FS
  • Strength 

You can use the following table to get them:


Once you have calculated the Factor of Safety (FS) and you have the value of the Strength, you will get Stressmax using the formula. Now you have the value of stress that sets a limit for your design.

In conclusion, the Factor of Safety is a very important concept in Mechanical Engineering because it allows engineers to design safe products. It can also help you make efficient designs by avoiding a Factor of Safety larger than necessary.

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