Welcome to Vibrationdata FAQs Page


Is there a published vibration test level for testing automotive components?
The proper method is to take accelerometer measurements on a representative vehicle at the component mounting location. The vehicle should be driven over a variety of road surfaces and at various speeds. This can be done at a proving ground, such as the Bosch test facility in New Carlisle, Indiana. Or you could do this on actual highways. or rough roads in the mountains or desert. You can then develop your own test levels.

Also, refer to MIL-STD-810F, Method 514.5, Vibration. See paragraph 2.2.1 and Figure 514.5C-1. This document is available at: Testing Standards.

What is the damping value for a particular material?
There are many types of damping, such as viscous, hysteresis, acoustic coupling, air pumping at joints, energy radiation to the soil, etc. Also, boundaries and bearings contribute damping.
In addition, structures have many modes. Each mode may have a unique damping value.
Damping may be non-linear. It may vary with the excitation level.
Thus, testing is necessary to determine the damping value for a given material and design configuration.
Some references are given at: Damping Page.
How can I measure dynamic displacement or velocity with an accelerometer?
I recommend using a B&K 2635 (or equivalent) charge amp with a B&K charge mode accelerometer. (Disclaimer: I am not a B&K salesman).
This charge amp model performs integration on the analog acceleration signal in the time domain after passing the signal through an analog high-pass filter. The high-pass filter frequency has several settings. A typical setting might be 1 Hz. The filter removes the DC offset which would otherwise cause the slope effect in the velocity signal.
The alternative is to integrate the digital accelerometer signal to obtain velocity. The acceleration signal can be double-integrated to obtain displacement. The problem is that any spurious offset in the acceleration signal will be magnified in the integration process, resulting in the slope effect.
What is a good reference for learning finite element analysis?
I recommend:
V. Adams and A. Askenazi, Building Better Products with Finite Element Analysis, OnWord Press, Santa Fe, N.M., 1999.


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