Fließgrenze

Fließgrenze, also known as yield strength, is a fundamental material property that describes the stress at which a material begins to deform plastically. Up to this point, the material will return to its original shape if the applied stress is removed, exhibiting elastic behavior. Beyond the Fließgrenze, the deformation becomes permanent. This transition is critical in engineering design, as exceeding the Fließgrenze can lead to irreversible damage or failure of a component.

The Fließgrenze is typically determined through a tensile test. In this test, a standardized sample of the material is subjected to increasing tensile stress, and its elongation is measured. The stress-strain curve generated from this test shows a distinct point where the slope changes, indicating the onset of plastic deformation. For some materials, like many steels, there is a clear yield point. For others, such as aluminum alloys, the transition is more gradual, and an offset method is used to define the Fließgrenze, usually at a 0.2% plastic strain.

Understanding the Fließgrenze is essential for selecting appropriate materials for specific applications. Engineers use this value to ensure that components can withstand operational loads without permanent deformation. It plays a crucial role in calculations for structural integrity, machine design, and safety analysis. Materials with a higher Fließgrenze can generally support greater loads before permanent deformation occurs.