Bob Metz is pressure force product manager at PCB Piezotronics Inc. (Depew, NY). For more information, call (888) 684-0004, e-mail [email protected] or visit www.pcb.com.
A major cause of overtesting of spacecraft, aerospace and flight hardware during random and swept sine vibration tests is associated with differences between the mechanical impedance of the shaker and mounting fixture, and the standard practice of controlling the input acceleration to the frequency envelope of the flight data. The result is artificially high shaker forces and responses at the resonance frequencies of the test item. These high forces can damage expensive payloads.