{"id":294072,"date":"2023-07-20T10:07:49","date_gmt":"2023-07-20T10:07:49","guid":{"rendered":"\/forum\/forums\/topic\/component-fatigue-behaviour\/"},"modified":"2023-07-27T07:59:34","modified_gmt":"2023-07-27T07:59:34","slug":"component-fatigue-behaviour","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/component-fatigue-behaviour\/","title":{"rendered":"Component fatigue behaviour"},"content":{"rendered":"

Hello,<\/p>\n

I am playing with a parametrical optimisation<\/strong>. The objective function is reducing the mass, and all the contraints are regarding the lifetime. The min lifetime that i want is 25.000. This optimisation is about a structural steel<\/strong> component.<\/p>\n

The model have geometrical singularities<\/strong> (witch are also making a contact), so, from this point of view i decided that i should estimate the lifetime using strain-life parameters<\/strong> ( and i think is not very bad because 25.000 is aproximative in the limits of low cycle fatigue).<\/p>\n

I am using the default strain-life parameters of structural steel<\/strong>. <\/p>\n

It is clear that i need to define the plasticity of the material. I had choose the multilinear isotropic hardening<\/strong> approach, but it does not have default values, so i needed to chose them from literature.<\/p>\n

So, the problem<\/strong> is that i do not have any ideea if the strain stress curve<\/strong> should be the engineering one<\/strong> or the real one<\/strong>. (or even a mixture, the engineering strain and the real stress).<\/p>\n

I think the FEM approach should have the real curves and characteristics of the material…but i am not sure if the default values for strain-life parameters are real or engineering ones. <\/p>\n

It is also for the first time when i see how is defined in ansys the low cycle fatigue behaviour.<\/p>\n

I tried a lot of combinations on a cube model but i did not saw anything realistic.<\/p>\n

I think the strain-life parameters are not defined in accordance with the real curve that i found in literature, maybe this is the problem and it can be for choosing a wrong material to read about(i searched for S275)<\/p>\n","protected":false},"template":"","class_list":["post-294072","topic","type-topic","status-closed","hentry","topic-tag-fatigue-analysis","topic-tag-isotropic-hardening","topic-tag-stress-strain-curve"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t