# Stress Concentration Factor at a Hole

Last updated: December 31, 2018

## What Does Stress Concentration Factor at a Hole Mean?

The stress concentration factor at a hole is a dimensionless constant used to quantify the increase in internal stresses that occur in a loaded structural member with a circular-shaped opening. This increase is typically observed near the hole and can be significantly higher than the average stress across the object’s cross-section. This value is important when considering the stress placed upon a component in a structure.

## Corrosionpedia Explains Stress Concentration Factor at a Hole

When a circular opening (hole) causes the internal stress in a section to increase, the hole is referred to as a stress riser.

For an elliptical opening the maximum stress at the edge of the hole in a loaded section is given by the formula:

σ3 = σ1.(1 + 2b/a)

Where:

σ3 = the maximum stress in the section

σ1 = the average uniform stress in the section

a = the width of the hole

b = the length of the hole

For a circular section, where a = b, then σ3 = 3.σ1; thus, the stress concentration factor at the edge of a circular hole is 3.0. In other words, the stress at the edge of the hole is expected to be three times higher than the average stress in the section. 