failure crterion for powdered metal

[LTR]

I am designing a small powdered metal part for the automotive market and I am not sure what failure criteria I should use for the FEA. The part will see a significant bolt up load but very little dynamic load. Elongation at fracture of this material is about 4%. Should I consider it a failure when the max principle stress exceeds the yield strength of the material (i.e. max principle stress theory)? This seems appropriate since the material is brittle but I don't have much experience with powdered metal.

Thanks,
Mel Lang

 

[arunmrao]

A powder metallurgical part is never as dense as those made from bar stocks etc. There are internal voids which can be interconnected. Normally porosity varies from 5-15% depending on the processing and end requirement. You need to factor this aspect in your calculation.

what is the powder alloy you are processing and the part being made? Perhaps soon others would join in,once enough details are available.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[TVP]

Maximum principal stress = to yield strength is a reasonable method for modeling PM parts. Don't use von Mises. High stress intensities are very detrimental in PM parts, so make sure the stresses are compressive if at all possible.

 

[LTR]

Thanks for the responses. The material is FC0208-60.