Stress Concentration at a Notch
Stress Concentration at a Notch
Holes, fillets and notches locally magnify stress; the concentration factor turns the nominal stress into the real peak.
The peak stress is σ_max = K_t·σ_nom. where K_t is the stress concentration factor and σ_nom the nominal stress.
Inputs
K_t := 2.5=2.5
sigma_nom := 80 MPa=80 MPa
Multiply nominal stress by the concentration factor.
sigma_max := K_t·sigma_nom=200 MPa
Results
The local peak can be several times the nominal stress, which is where fatigue cracks start. Generous fillets and smooth transitions lower K_t.
Assumptions & limitations
- Elastic stress concentration.
- K_t from charts/geometry.
- Static; fatigue uses a related factor.