jännysvenymäkäyrät

Stress-strain curves, known in Finnish as jännysvenymäkäyrät, are graphical representations that illustrate the relationship between stress and strain for a material under tensile or compressive load. Stress, typically plotted on the y-axis, represents the force applied per unit area, while strain, plotted on the x-axis, represents the deformation of the material relative to its original dimensions.

The initial part of a typical stress-strain curve for a ductile material is often linear, representing the elastic region. In this region, the material will return to its original shape once the load is removed. The slope of this linear portion is known as the Young's modulus or modulus of elasticity, a measure of the material's stiffness.

As the stress increases beyond the elastic limit, the material enters the plastic region. Here, deformation is permanent, and the material will not return to its original shape. Within the plastic region, there's often a point of yielding, where the material begins to deform significantly with little increase in stress. Further increase in stress leads to strain hardening, where the material becomes stronger and more resistant to deformation.

The curve reaches a peak stress, known as the ultimate tensile strength, which is the maximum stress the material can withstand before it begins to neck (localize deformation). Finally, the material fractures at the fracture stress, marking the end of the curve. The area under the stress-strain curve represents the toughness of the material, its ability to absorb energy before fracturing.