Review of Recent Developments in Multiple-Reference Impact Testing

Impact testing was one of the first practical applications of the fast-Fourier transform (FFT) technique in the late 1960s. Prior to developing the FFT, measuring the frequency response function (FRF) was limited to sinusoidal testing procedures. The sine testing methods were slow, and required elaborate fixtures for excitation (electro-mechanical or hydraulic exciters). Impact testing provided an order of magnitude faster test time and minimal fixtures. As a result, it became a very good field-testing and troubleshooting method, as well as a pretesting method for controlled laboratory testing. This article is a general review of the evolution of impact testing from its development in the 1960s and '70s to the present time, with a more extensive review of recent developments in testing procedures and parameter estimation for multiple-reference impact testing (MRIT).