Venymäkäyrä

Venymäkäyrä, often translated as strain curve or deformation curve, is a graphical representation of the relationship between stress and strain in a material under tensile or compressive load. It is a fundamental tool in materials science and engineering for understanding a material's mechanical properties. The horizontal axis of the curve typically represents strain, which is the relative deformation of the material (change in length divided by original length), and the vertical axis represents stress, which is the applied force per unit area.

The shape of the venymäkäyrä reveals crucial information about a material's behavior. In the initial region, for many materials, there is a linear elastic portion where stress is directly proportional to strain, described by Hooke's Law. Beyond this elastic limit, the material may undergo plastic deformation, meaning it will not return to its original shape upon unloading. The curve often shows a yield point where plastic deformation begins, followed by strain hardening, where the material becomes stronger and more resistant to further deformation. Finally, the curve reaches its ultimate tensile strength, the maximum stress the material can withstand, before fracturing at the point of fracture. Different materials, such as metals, ceramics, and polymers, exhibit distinct venymäkäyrät reflecting their unique mechanical responses.