Jännitysrasituskäyrät

Jännitysrasituskäyrät, also known as stress-strain curves, are graphical representations used in materials science and engineering to illustrate the relationship between stress and strain experienced by a material under tensile or compressive load. These curves are fundamental for understanding a material's mechanical properties.

The horizontal axis typically represents strain, which is a measure of deformation (change in length divided by original length), and is usually dimensionless or expressed as a percentage. The vertical axis represents stress, which is the applied force per unit area, typically measured in Pascals (Pa) or pounds per square inch (psi).

A typical jännitysrasituskäyrä for a ductile material begins with a linear elastic region where stress is directly proportional to strain, following Hooke's Law. Beyond the elastic limit, the material enters the plastic deformation region, where permanent deformation occurs. The yield strength is the point at which plastic deformation begins. The curve then shows a period of strain hardening as the material resists further deformation, until it reaches its ultimate tensile strength, the maximum stress the material can withstand. Finally, the curve drops as necking occurs, leading to fracture at the rupture point.

Brittle materials, on the other hand, exhibit a shorter elastic region and fracture with little to no plastic deformation, resulting in a steeper curve that breaks abruptly. Jännitysrasituskäyrät provide crucial data for material selection, design calculations, and failure analysis.