Stress Concentration Factor Calculator

What Is a Stress Concentration Factor?

Stress concentration factor \(K_t\) compares the peak local stress at a notch, hole, or fillet to the nominal (average) stress in the section. Sharp changes in geometry redirect load paths and raise local stress above the simple average.

Circular Hole in a Plate

For a central hole of diameter \(d\) in a plate of width \(w\), with \(d/w < 0.5\):

Maximum stress is \(\sigma_{\max} = K_t \cdot \sigma_{\text{nom}}\).

Shoulder Fillet

For a rounded fillet with radius-to-diameter ratio \(r/d\), this tool uses a practical approximation \(K_t = 1 + 2/(1 + 10 \cdot r/d)\). Larger fillet radius reduces \(K_t\).

Related tools: Torque Calculator and Rotational Stiffness Calculator.