Choose one

or multiple languages


0,1,1
  • German
  • English
  • Chinese
  • Spanish

Failure theories


Failure theories are used if an experiment is unable to analyse all possible states of stress in a component.

Components are normally subject to multiaxial stresses that induce a two-dimensional or three-dimensional state of stress. Up to three normal stresses and three shear stresses (components of a stress matrix) can occur simultaneously in a component.

Failure theories are used to calculate an equivalent stress from the stress components and this is compared with uniaxial Strength values. The condition ${{\sigma }_{current}}\ge {{\sigma }_{permissible}}$ needs to be met to prove the durability of a component or structure.

Various failure theories are used depending on the Material and Failure mode. They include:

  • principal Normal stress theory, which is used to evaluate failure due to the rupture of brittle materials
  • distortion energy theory, which calculates the flow-related failure of tough, ductile materials
  • principal Shear stress theory, which illustrates the pressure-related failure of brittle materials with a pronounced yield point.

Equivalent stress theories are only suitable for isotropic materials. They do not Work with anisotropic materials such as fibre composites and Wood derivatives.

Further search


item


Discover innovative solutions
for machine building and automation.

Go to the website