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Experimental modal analysis - driving point

Creator
Creator
I have measuring experimental modal analysis in exhaust system assembly, in this exhaust geometry nodes point for 16 points. I did measurement method for roving accelerometer method. but I can't identify driving points of exhaust system geometry.
how to select the driving points and how to measure
1 REPLY

Re: Experimental modal analysis - driving point

Siemens Phenom Siemens Phenom
Siemens Phenom

Hello,

 

The driving point measurement is the location where:

  • The accelerometer and the force are measured at the same location.  This can be done by using a hammer and hitting next to the accelerometer or if using a shaker with an impedance head that measures both force and acceleration.  Or with a shaker placing the accelerometer next to the force transducer.
  • The geometry location for the accelerometer and the force measurement has exactly the same name (Point ID).  The direction can be reversed though, i.e. force could be -Z and acceleration could be +Z for example.

If both those are true we know it's a driving point measurement and modal mass and modal stiffness can be calculated.  Without the above being true, we cannot calculate modal mass or stiffness and some tools like modification prediction or rigid body calculator cannot be used.  Some people make the mistake of calling the hammer location "hammer" or such.  All measurements must be tied to the geometry for force and acceleration.