Multiaxial analysis
In: Fatigue calculation methods
A very often concept in multiaxial analysis is an examination of local load state on a plane. The normal and shear components on a plane are evaluated usually. An external sign of the criterion's multiaxiality is the composition of the damage parameter from at least two local load state components. This is in contrast to uniaxial methods, which process one scalar equivalent load only.
The interaction of the two or more load quantities should better describe the problematic cases of non-proportional loading. It is expected usually, that the shear component has a primary effect on the lifetime, whereas the normal component has a secondary although significant effect.
There are several ways, in which the multiaxial criteria are build:
* critical plane criteria – the damage in the point examined is related to one specific plane;
* integral criteria – either whole damage parameter or some its components are integrated over all planes in the point examined - the introduction of the integration into the final damage corresponds to averaging of the plane specific damage parameter;
* criteria using Ilyushin deviatoric space – one load parameter is retrieved from a load path transformed to a 5-dimensional Ilyushin space, the other parameter is related to some other unique scalar quantity.
The last section of the multiaxial analysis clearly includes criteria non-related to any specific plane.
More:
multiaxial methods within local elastic-plastic strain methods
multiaxial methods within local elastic stress methods
criteria using Ilyushin deviatoric space
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