Fortfrakturer

Fortfrakturer is a term used in materials science to describe a class of rapid fracture events in solids in which crack propagation occurs under high-rate loading and advances at substantial fractions of the material’s characteristic wave speeds. The term combines elements referring to speed (fort, from Swedish fast) and fracture (frakturer). The concept is employed to distinguish fast, dynamic crack growth from quasi-static fracture processes.

Causes and mechanisms: Fortfrakturer arise when applied stresses exceed the material's fracture toughness on timescales shorter than microstructural relaxation. In brittle materials, inertia and adiabatic heating can promote rapid crack propagation and branch formation; in ductile materials, rate-dependent weakening and microvoid coalescence can also contribute. Microbranching and arrest-restart cycles may occur, leading to complex fracture surfaces. The specific thresholds depend on material properties, temperature, and the loading rate.

Detection and modeling: Observations rely on high-speed imaging, digital image correlation, and laser Doppler vibrometry during impact, ballistic, or shock tests. Numerical approaches include dynamic fracture mechanics with rate-dependent cohesion laws, cohesive zone models, and phase-field methods adapted for high strain rates.

Applications and significance: Understanding fortfrakturer is relevant for safety-critical design in aerospace, automotive, and protective equipment, where components may experience impacts, blasts, or high-rate loading. Insights inform material selection, notch design, and fracture resistance criteria under dynamic conditions. The term remains less standardized than broader terms such as dynamic fracture, and its usage varies by field.