Properly-featured modal exciters and amplifiers are critical to acquiring good experimental modal data and valid frequency response functions. Thus, the only option is to excite with one or more modal exciters. Also, the benefits of random, burst random, pseudo-random, and sine sweep and dwell excitations may be needed for good FRFs. Often, however, multiple input forces must be used, the excitation forces must be controlled, the structure is non-linear, the excitation energy must be tailored differently across different frequencies, or excitation forces must be input and distributed across the structure so as to minimize the effects of local modes or high damping.
Impact or hammer excitation is a quick and often effective means for modal surveys.
Modal test results help troubleshoot resonant excitation from operating forces, validate and verify finite element models, predict the benefits of structural modifications, support design verification, and understand structural responses due to complex loading conditions.Ĭontrolled excitation tests involve exciting the structure and measuring input forces and acceleration responses at a few or many locations. Modal tests identify a structure’s modal properties: natural frequencies, mode shapes, mass, stiffness and damping.
Experimental modal analysis, or modal testing, is a process for physically obtaining a math model of a structure’s dynamic properties.
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