Pretest Analysis

Pretest analysis ensures that the test program successfully yields useful data. For example, pretest modal survey analysis is utilized to identify target modes, define accelerometer numbers/locations to ensure proper target mode capture, and define exciter locations to ensure proper modal excitation. ASD has a unique approach to pretest analysis which has paid big dividends for our clients. ASD utilizes its expertise in structural dynamics and finite element modeling to perform a complete review of the client structural finite element model mode-shapes to ensure structural realism. As an example, on one test program, the finite element model initially predicted 12 target modes below 50 Hz. After studying the mode-shapes, ASD identified multiple modes that were unrealistic. With the client’s approval, the modeling of various structural interfaces were upgraded, yielding a realistic hardware behavior prediction. This resulted in the number of pretest target modes below 50 Hz dropping to just 2 which were later verified at the modal survey test.