Post processing help in ANSYS

[windsoreng]

I am modelling a plastic part in ANSYS 12.2

I applied mesh,connections, forces and suports.

I solved and got solution

I applied a froce of 1200N

Max stress was at 206 MPa

UTS of material is at 135 MPa

I need to find the force (which should be less then 1200N) at which the part will fail, any way other then trail and error, to find that out?

Thanks

 

[Drej]

What do you mean by "fail"? Fail how?


------------
See faq569-1083 for details on how to make best use of Eng-Tips.com

 

[windsoreng]

For ex UTS of material is at 135 MPa, and I apply force of 1200N, accoring to the counters in ANSYS the Max stress is 206 MPa at one spot it means its gona fail there.

I need to find a force that would generate stress within UTS of material.

 

[Drej]

No. Just because a material reaches "a stress" of/beyond UTS under load doesn't mean it will "fail". What if a material is perfectly plastic - stress is meaningless in this respect. Strain (equivalent or instantaneous depending on the loading) is generally used to assess this, but you need a justification based on defined criteria.

I ask again, fail how? Fail a code? Fail by plastic collapse? Fail by plastic damage or other damage mechanisms? You need to think carefully about understanding and prescribing failure criteria for this design/structure/material/loading. If you want to use "UTS of stress" as your failure criteria then fine, but it's not something that I would be happy to provide as a justification.


------------
See faq569-1083 for details on how to make best use of Eng-Tips.com