Failure Analysis Criteria
Failure Analysis Criteria
(OP)
I am analyzing an aluminum enclosure subjected to an interior pressure. The FEA package I'm using allows me to view several stress results such as Von Mises, max and min principle, etc...
I want to know whether or not the enclosure will rupture with the presence of an internal pressure. Which stress (Von Mises, principal, ???) do I compare against the yield and ultimate strengths of the aluminum?
I want to know whether or not the enclosure will rupture with the presence of an internal pressure. Which stress (Von Mises, principal, ???) do I compare against the yield and ultimate strengths of the aluminum?





RE: Failure Analysis Criteria
RE: Failure Analysis Criteria
Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
RE: Failure Analysis Criteria
Sean
RE: Failure Analysis Criteria
RE: Failure Analysis Criteria
sean001 - Like GBor said, it isn't really going to matter. However, your are going to find locations where the local stress exceeds yield - and that _may_ be OK. I would again recommend that you check out ASME Section VIII, Division 2 - particularly Appendix 4.
Are you doing an actual failure analysis of a failed part, or are you designing a part to avoid failure?
RE: Failure Analysis Criteria
as pointed out by TGS4, I'd first of all check if you have to conform to some Norm or not. There are only very few cases where you can design a pressure vessel without refering to some Norm, be it ASME or european PED or others. Then, your design and calculations will have to carefully respect the appliable Norm.
For example, ASME will "oblige" you to consider TrescĂ -Guest, while PED is built upon VonMises.
If you are free to choose (lucky...), I'd suggest european PED instead of ASME because it's far more recent and has made treasure of the latest improvements in material science. Its "direct route", which needs non-linear solution by default, is computationally "heavy" but can lead to exceptional results if you are designing a new component (less useful if you are verifying a failed component, though...).
Regards
RE: Failure Analysis Criteria
corus
RE: Failure Analysis Criteria
The enclosure is not a pressure vessel (per se) or boiler. It is an explosion proof electronic enclosure. The design is guided by UL 1203 and ATEX Zone 1 specs. I reveiwed the specs and cannot see anything about failure analysis.
This is a new design. I'm trying to determine if the design will contain an explosion if the vapors inside ignite. I am not investigating a failed component.
The software we use does not have non-linear analysis, though it can be added on. Based on GBor's earlier comment, if the stress stays below yield that should not present a problem.
Thanks everyone.
Sean
RE: Failure Analysis Criteria
RE: Failure Analysis Criteria
obviously if the box is trying to contain an explosion, then it'll be loaded in tension.
how do you calculate the pressure of an explosion ? i guess chemistry allows to you to calculate the volume of the products, how about the time release of these ??
think too about a "leak before burst" type of design ... maybe it's enough for the pressure box to absorb some of the energy of the explosion rather than all of it.