Jännitystaipumiskäyrät

Jännitystaipumiskäyrät, often translated as stress-strain curves, are graphical representations used in materials science and engineering to illustrate the relationship between stress and strain for a given material. A stress-strain curve is generated by applying a controlled tensile or compressive force to a material sample and measuring the resulting deformation. Stress is defined as the force applied per unit area, while strain is the relative deformation or change in length.

The typical stress-strain curve begins with a linear elastic region. In this phase, the material deforms elastically, meaning it 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. Following the elastic region, the curve enters the plastic deformation region. Here, the material undergoes permanent deformation and will not recover its original shape.

Within the plastic region, the material may exhibit a yield point, where the stress required to cause further plastic deformation decreases slightly, or a yield strength, which is the stress at which significant plastic deformation begins. As the stress continues to increase, the material strain hardens, becoming stronger and more resistant to deformation. The curve reaches a maximum stress point, known as the ultimate tensile strength, which represents the highest stress the material can withstand. Beyond this point, the material begins to neck, reducing its cross-sectional area, and the stress decreases until fracture occurs. The area under the stress-strain curve up to the point of fracture represents the toughness of the material, its ability to absorb energy before breaking.