Fejldéselmélet

Fejldéselmélet, often translated as Failure Theory, is a branch of engineering mechanics that deals with predicting the onset of failure in materials under various stress conditions. It is crucial for ensuring the safety and reliability of structures and components in mechanical and civil engineering. Failure theories aim to establish criteria that define the boundary between elastic or ductile behavior and catastrophic failure, such as yielding, fracture, or rupture.

Different theories exist because material behavior under complex stress states is not always straightforward. For ductile materials, the von Mises yield criterion and the Tresca yield criterion are commonly used. The von Mises criterion is based on the distortion energy theory, while the Tresca criterion is based on the maximum shear stress. For brittle materials, theories like the maximum principal stress theory and the Mohr-Coulomb theory are more appropriate, considering their tendency to fracture rather than deform significantly.

The application of failure theories involves calculating the stress state at critical points within a structure and comparing these stresses to the material's yield or ultimate strength, as defined by the chosen theory. The selection of the appropriate failure theory depends on the material's properties (ductile vs. brittle) and the type of loading applied. Understanding and correctly applying these theories is essential for designing components that can withstand expected loads without failing prematurely, thereby preventing accidents and ensuring economic viability.