GETTING THE MOST OUT OF COMMERCIAL MODAL SYSTEMS

摘要

Modal analysis is a powerful tool. But like any tool, if it is applied by inexperienced users, the results may be disappointing. Commercially available systems have evolved to a fairly sophisticated degree - most are powerful, fairly easy to use, and provide various levels of assistance for the inexperienced user. All current systems, however, have certain characteristics (most notably, the inability to handle rotational degrees-of-freedom) that can limit their successful application to fairly simple problems, particularly if test results are used in predictive analytical models. This paper will review some of the characteristics of "canned" modal analysis systems and present some simple techniques that can be used to greatly enhance the capabilities of (and increase confidence in) their use. Examples will include illustrations of problems encountered due to the lack of rotational degrees-of-freedom capabilities and how to avoid these problems; computation of joint and boundary conditions from simple experimental data, including connection points where no data exists; a strategy for designing products to make them more amenable to analysis; and some reasons for the difficulties encountered in predictive analysis.