Jäännöstressi

Jäännöstressi, often translated as residual stress, refers to the internal stresses that remain within a solid material after manufacturing or processing. These stresses are self-equilibrating, meaning that no external forces are applied, yet the material is under tension or compression in different regions. Jäännöstressi can arise from various sources, including plastic deformation, rapid cooling or heating, and surface treatments like shot peening or grinding.

The presence of jäännöstressi can significantly influence a material's mechanical properties. For instance, compressive residual stresses on the surface can enhance a component's resistance to fatigue crack initiation and propagation, thereby increasing its lifespan. Conversely, tensile residual stresses can promote crack growth and reduce fatigue strength. Understanding and controlling jäännöstressi is crucial in many engineering applications to ensure the reliability and performance of manufactured parts.

Methods for measuring jäännöstressi include destructive techniques like the hole drilling method or the layer removal method, which involve removing material and observing the resulting deformation. Non-destructive methods, such as X-ray diffraction or ultrasonic testing, are also employed. The ability to predict, measure, and manage jäännöstressi is a key aspect of materials engineering and product design.