How to install strain gages in case of cyclic loading of a pipe

[Znjmech]

Hi All

I have a pipe ( clamped from one side ) while a lateral load and a moment is being applied to the other end. due to the geometry difficulties, I need to install the strain gages near the loading end, where also the fracture happens. the loads are being applied in a harmonic regime under 10 Htz.

I would like to know how to install them ( orientations ) and calculations ( do they enter in polar coordinates ?) and possible errors and maximum temperature I can use a strain gage( this last one just for info)

 

[Ron]

If you are using linear gages, I would install one gauge at the top, one at the bottom and one along the side or perceived neutral axis for bending. This will tell you a lot about how the load is being received by the member. The top and bottom gages should be redundant and opposite; however, if they show differences, then you likely have some lateral load influence.

You can also use an rosette gages in a variety of configurations to check shear, torque and eccentric loading.

Gages are made for a wide range of temperatures and exposures. You should be able to find a gage for almost any reasonable temperature range.

Calculations are straightforward and depend on the gages used, their gage factors, their length, etc....all of which are readily obtainable. As long as the material remains in the elastic stress range, the calculation is simply a stress-strain relationship for the particular material being used.

 

[dik]

Can you use a pair of LVDTs to electronically monitor the movement in two directions?

Dik