Timeline for Why do beverage can tabs break when bent?
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 27, 2016 at 2:17 | comment | added | Chris Johns | By definition fatigue occurs at loads significantly below the yield stress for the section in question, this is a very important distinction between fatigue and post yield fracture as it is possible for fatigue to cause failure even when the static design load is never exceeded. | |
| Apr 10, 2015 at 18:14 | comment | added | Air | The magnitude of this deformation is on a totally different scale from what you would expect in a cyclic loading scenario. You can break the tab off without even performing a complete cycle. The cold working/embrittlement answer goes directly to the root cause without requiring the special case of cycling loading, so I think it's a bit better of an explanation. | |
| Apr 10, 2015 at 16:37 | comment | added | Dan | Part of the crack propagation mechanisms responsible for fatigue involve local (microscopic plastic deformation. Seem like a semantics argument to me. | |
| Apr 10, 2015 at 16:27 | comment | added | BeyondLego | Fatigue (to the best of my knowledge) only applies when the loading is below the material's yield stress, which is definitely not the case here since it plastically deforms with every bend. | |
| Apr 10, 2015 at 3:24 | comment | added | Trevor Archibald | That link says "low-cycle fatigue." is 10,000 cycles or fewer. 3 is in fact fewer that 10,000, but I still think we're more in the range of plastically deforming it until it breaks. Fatigue loading will still not go above the UTS or the elongation limit of the material, I think this failure mode does. | |
| Apr 10, 2015 at 3:22 | comment | added | Dan | @TrevorArchibald we might be splitting hairs here, but what you're describing seems to be what is referred to as 'low-cycle fatigue'. | |
| Apr 9, 2015 at 20:45 | comment | added | Trevor Archibald | I disagree, I don't think fatigue is really a consideration when the part lasts for 3 cycles. The cyclic loading is a factor, but it's more because the plastic deformation remains after the tab is returned to its natural position. | |
| Apr 9, 2015 at 18:48 | history | answered | C0V3RT_KN1GHT | CC BY-SA 3.0 |