Strain Life Method and Material Hysteresis


Hi all!


I want to assess fatigue life of a component undergoing to local plastic deformation due to a repeated irregular load hystory. I can assume that the load is quasistatic. I do not want to use the Neuber correction in Virtual.Lab to perform the durability analysis. Therefore, I selected the no correction option in the Strain Approach tab of Strain Fatigue Parameter window.


In this case, is it correct using in Virtual.Lab an .odb file created using Abaqus, plastic material curves and no hysteresis material model? I presume that with no Neuber correction, Virtual.Lab will read the stress and strain history from the .odb to evaluate the hysteresis loops.


In case I do not want to  use Abaqus material Hysteresis model, should I instead activate the Neuber Correction and use .odb result file with stress calculated with elastic material curves? I presume that with Neuber correction enabled, Virtual.Lab will use the Masing model to evaluate the hysteresis loops. 


Re: Strain Life Method and Material Hysteresis

Siemens Genius Siemens Genius
Siemens Genius

Dear Hen,


The strain-life model in VIrtual.Lab (to be exact the pseudo-stress based strain-life model) assumes a local uni-axial stress state (either by critical plane or by equivalent stress) To be locally consistent, we Take the Stresses from FE and project them into the uni-axial stress state. To get to the strains we then either use Neuber together with the stress-strain curve or by no correction directly the stress-strain curve to get to the local stress-strain path using Masing-Memory models. (So the latter is always used)


So to be consistent when using no correction, your FE - model should use a material model consistent to the one locally used. If you do not want to use a FE material model with kinematic hardening (Hysteresis model) use a Neuber based approach.


Hope that is clear





Dr.Michael Hack
Business Product Line Manager
Durability Simulation