Are My Hammer Impact Results Valid? (3) Time Invariance
As mentioned in our previous two articles, when performing experimental modal testing of a structure or component using impact (or ping) testing, it is important to consider and verify the…
Are My Hammer Impact Results Valid? (2) Reciprocity
As mentioned in our previous article, when performing experimental modal testing of a structure or component using impact (or ping) testing, it is important to consider and verify the validity…
Are My Hammer Impact Results Valid? (1) Linearity
When performing experimental modal testing of a structure or component using impact (or ping) testing, it is important to consider and verify the validity of any results. A modal analysis…
Hammer Testing: Free or fixed support?
A vital question to be asked before performing hammer testing is - how do I support the testing object? What fixing mechanism to use? Or technically, what are the desired…
Figure 5: H1(f)
A Simple Frequency Response Function
The following article will attempt to explain the basic theory of the frequency response function (FRF). This basic theory will then be used to calculate the frequency response function between two points on a structure using an accelerometer to measure the response and a force gauge hammer to measure the excitation.
Fundamentally a FRF is a mathematical representation of the relationship between the input and the output of a system.
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