Volume 34, Issue 4 (July 2006)
Experimental Stability Analysis of a Test System for Doing Fatigue Tests under Random Loading
A test system is expected to run without being out of control for a laboratory fatigue test under random loading. In this regard, one needs to avoid two things. One is unexpected overloading at the beginning of the test system runs and the other, unexpected interruptions occurring during a test. This paper explains the importance of setting the cutoff frequency of a test system for dealing with the two control issues mentioned above. The results in this paper suggest a way to avoid the two unstable behaviors of the test system by setting a small cutoff frequency at the beginning of the test but a large cutoff frequency during the test. This work is based experimentally on an Instron 2165 electrohydraulic system for doing laboratory fatigue tests under random loading.