Measuring Vibration on Screws in Vehicle Flanges

[serbring]

Hi guys, in my company we have seen a lot a failures on a flange, in particular one flange screw strips. This flange is mounted in a vehicle and it support some hydraulic pipes. The designer thinks vibrations should cause the failure and so he suggests me to measure the flange acceleration along the screw axis. But how can I understand if the acceleration are too high?

 

[drMS]

Hi guys, in my company we have seen a lot a failures on a flange, in particular one flange screw strips. This flange is mounted in a vehicle and it support some hydraulic pipes. The designer thinks vibrations should cause the failure and so he suggests me to measure the flange acceleration along the screw axis. But how can I understand if the acceleration are too high?

Hi--from the acceleration signal you should be able to reconstrunct the loal diplacement as function of time. Then, you could do some FEM calculations on the structure, maybe checking for fatigue failure.

M

 

[nvn]

serbring: Is this a tapped hole? Post all dimensions, thread size, thread engagement length, material specifications, bolt installation torque, lubrication, and applied loads. Has the tapped hole been measured, to ensure the fabricator is not tapping the hole with sloppy thread tolerance, exceeding the thread tolerance specified on the drawing? Perform a bolt stress analysis, to determine if the thread shear stress exceeds the proof stress. Perhaps try a bolt with a polymeric locking patch.

 

[serbring]

serbring: Is this a tapped hole? Post all dimensions, thread size, thread engagement length, material specifications, bolt installation torque, lubrication, and applied loads. Has the tapped hole been measured, to ensure the fabricator is not tapping the hole with sloppy thread tolerance, exceeding the thread tolerance specified on the drawing? Perform a bolt stress analysis, to determine if the thread shear stress exceeds the proof stress. Perhaps try a bolt with a polymeric locking patch.

Hello nvn, yes it is a tapped hole. I will post all the data you need. Only one question: how do you handle those technical data?

 

[serbring]

Hi--from the acceleration signal you should be able to reconstrunct the loal diplacement as function of time. Then, you could do some FEM calculations on the structure, maybe checking for fatigue failure.

M

Hello drMR, ok I have understood, I will try to check if we have a FEM software.