Failure analysis help
Failure analysis help
(OP)
I've got some positive stops that have failed recently. see file attached for dimensions and pictures (10 MB pdf !).
Loads are ~0 to 50 kN, applied according the longitudinal axis of the legs. There is a minimal slope on the edge, so there is a small lateral component.
Parts have been in service for 20 years, meaning about 10^7 cycles.
No fatigue marks to be seen. This is also a failure % of 0.01% (lots of similar components, but not allot of them are 20 years old).
I see a number of welding errors (lack of fusion, not enough penetration).
Is there a way to check if dirt (coolant fluid from bandsaw, mill scale, grease, ...) could have been the original cause of this,
or, which is my opinion, this is just a way too small weld seeing the plates are much larger/thicker.
Your opinions please?
Loads are ~0 to 50 kN, applied according the longitudinal axis of the legs. There is a minimal slope on the edge, so there is a small lateral component.
Parts have been in service for 20 years, meaning about 10^7 cycles.
No fatigue marks to be seen. This is also a failure % of 0.01% (lots of similar components, but not allot of them are 20 years old).
I see a number of welding errors (lack of fusion, not enough penetration).
Is there a way to check if dirt (coolant fluid from bandsaw, mill scale, grease, ...) could have been the original cause of this,
or, which is my opinion, this is just a way too small weld seeing the plates are much larger/thicker.
Your opinions please?





RE: Failure analysis help
RE: Failure analysis help
I agree, with Corypad, evidence of fatigue in both Fig 7 and Fig 2. I also concur with your conclusion that the welds are much too small for the application, and that there is insufficient depth of fusion (penetration) into those thick members.
RE: Failure analysis help
RE: Failure analysis help
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"