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Mechanical Engineering vocabulary · Mechanics and Materials

Factor of safety

Meaning in mechanical engineering, with examples

nounCore term

In mechanical engineering, factor of safety means: The ratio between the load or stress a part can withstand and the load or stress it actually carries in use. A value of 2 means the part is twice as strong as needed.

In Turkish: emniyet katsayısı, güvenlik katsayısı, emniyet faktörü

How it is used

Used in every strength calculation and design review. Also called safety factor and written FoS or SF. The value chosen depends on how well the loads and materials are known and on how serious a failure would be.

Example sentences

  1. With a yield strength of 355 MPa and a maximum stress of 142 MPa, the factor of safety is 2.5.

  2. Lifting equipment needs a higher factor of safety than a simple machine cover.

Common collocations

  • safety factor
  • minimum factor of safety
  • apply a factor of safety
  • design factor
  • yield strengthThe stress at which a material stops behaving elastically and starts to deform permanently. Designers usually keep working stresses well below this value.
  • stressThe internal force inside a material divided by the area it acts on. It shows how hard a part is being pulled, pushed, bent or twisted and is measured in MPa or psi.
  • loadA force, weight or pressure that acts on a part or structure. Loads can be steady or changing and are the starting point of most strength calculations.
  • fatigueGradual damage and cracking of a material caused by loads that are applied and removed many times, even when each load is below the material's static strength.

More terms: Mechanics and Materials

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