The maximum stress a material withstands under tension before fracture.
Tensile strength (σ_UTS) is the peak engineering stress on the stress-strain curve, just before necking accelerates and the specimen fractures. For ductile metals it occurs well past yield; for brittle materials it coincides with fracture. Measured per ASTM E8 / ISO 6892-1 on dog-bone specimens. Reported in MPa.
In 3D-printed parts UTS governs whether brackets, snap-fits, and load-bearing fixtures survive worst-case load. FDM prints are anisotropic: XY strength is 2-4x Z-direction. PLA: 40-65 MPa; PETG: 45-55 MPa; PA-CF composites: 80-120 MPa. Always print test specimens in the actual build orientation.
Confusing UTS with yield strength leads to dangerous over-loading: permanent deformation begins well before UTS. Layer adhesion, print temperature, and cooling rate strongly affect FDM tensile strength. Datasheet values are for injection-moulded samples; Z-direction FDM values can be 30-50% lower.
Related terms: Yield Strength, Stress-Strain Curve, Elongation at Break, Necking, Ductility
| Field | mechanics, engineering |
|---|---|
| Also called | UTS, Ultimate Tensile Strength |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert