The five basic modes of structural failure in ships are:

1. Yielding – Excessive stress causes the material to deform permanently (plastic deformation) before fracture. Usually governed by exceeding the yield strength of the material under still-water and wave-induced bending/shear loads.

2. Buckling – Compressive loads (from hull girder bending, local panel loading, etc.) cause plates, stiffeners, or panels to lose stability and deflect out of plane, even though the material itself hasn’t yielded. Common in the compression flange of the hull girder (deck or bottom, depending on sagging/hogging).

3. Fatigue – Repeated cyclic loading (wave-induced stresses, vibration, slamming) over the ship’s service life causes progressive, localized crack initiation and growth, typically at stress concentrations like structural discontinuities, weld toes, or hatch corners — eventually leading to fracture even at stresses well below yield.

4. Fracture (Brittle or Ductile) – Sudden, often catastrophic crack propagation through the structure. Brittle fracture is particularly dangerous in cold conditions (relevant to your Arctic navigation interests) where steel toughness drops, allowing cracks to propagate rapidly with little plastic deformation — historically implicated in Liberty ship failures.

5. Corrosion-related failure (Wastage) – Progressive loss of material thickness due to general or pitting corrosion reduces the effective section modulus over time, lowering the margins against the other four failure modes and often acting as the trigger for fatigue crack initiation or reduced buckling/yield capacity.

In practice these modes interact — corrosion wastage accelerates fatigue and reduces buckling strength, and fatigue cracks can act as initiation sites for brittle fracture — so classification society rules (IACS CSR, etc.) address them together through structural design, inspection, and maintenance regimes rather than in isolation.