The ability of a material to absorb energy before fracture, equal to the area under the stress-strain curve.
Toughness U_T = ∫σ dε (from 0 to fracture strain). It combines strength AND ductility: a tough material must be both strong and able to plastically deform before breaking. Charpy and Izod tests measure impact toughness in J/m². Fracture toughness K_IC (MPa·√m) quantifies crack propagation resistance.
Toughness is the key criterion for parts surviving impact, drop, or shock loading: tool handles, drone frames, sports equipment. ABS and PETG are tougher than PLA; TPU is extremely tough. FDM layer adhesion creates crack initiation sites, reducing effective toughness below bulk values.
Do not confuse toughness with strength: a hard brittle material has high strength but low toughness. Charpy values for FDM parts depend strongly on notch orientation relative to layer direction. Published values are for 100% infill; 20% infill parts can have 50-80% lower toughness.
Related terms: Tensile Strength, Ductility, Brittleness, Elongation at Break, Impact Strength
| Field | mechanics, engineering |
|---|---|
| Also called | Impact Toughness, Fracture Toughness |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert