jännitystaipumiskäyrä

Jännitystaipumiskäyrä, often translated as stress-strain curve, is a graphical representation of a material's mechanical response to applied tensile stress. It plots engineering stress on the y-axis against engineering strain on the x-axis. The curve provides crucial information about a material's properties, including its stiffness, strength, and ductility.

The initial part of the curve, the elastic region, is typically linear, indicating that the material deforms elastically and will return to its original shape upon removal of the load. The slope of this linear portion represents the Young's modulus or modulus of elasticity, a measure of stiffness. Following the elastic region is the plastic region, where deformation is permanent.

Within the plastic region, the material may exhibit a yield point, the stress at which it begins to deform plastically. Beyond the yield point, the stress often increases with strain due to strain hardening, until it reaches its ultimate tensile strength, the maximum stress the material can withstand. After reaching the ultimate tensile strength, the material may begin to neck, a localized reduction in cross-sectional area, and fracture occurs at the fracture stress.

The shape and characteristics of the stress-strain curve vary significantly depending on the material. Brittle materials, such as ceramics and cast iron, typically show a short elastic region and fracture with little or no plastic deformation. Ductile materials, like many metals, exhibit a distinct plastic region with significant elongation before fracture. Understanding the stress-strain curve is fundamental in material science and engineering for material selection, design, and performance prediction.