1SOUND AND VIBRATION/JANUARY 2005 Until very recently

Finite Element Analysis (FEA) and Ex-perimental Modal Analysis (EMA) have been very separate engineering activities aimed at solving a common problem. Now the two technologies are converging and powerful new tools for solving noise and vibration problems are emerging as a result. The recent term Experimental FEA has emerged. This article provides a “lab-rat’s view ” of what this term re-ally means and why it is so valuable to today’s S&V practitio-ner. Experimental FEA is an integrated collection of modeling and analysis tools designed to be used by the experimentalist. It includes the facility to quickly build simple small-scale fi-nite element models and solve them for natural frequencies and mode shapes. The intent here is not to replace the traditional analyst’s tools, which are far more comprehensive and detail-focused. Rather, Experimental FEA is intended to augment the experimental understanding of structures by aiding us to per-form better modal tests, faster. Experimental FEA is essential to test planning. It provides scientific answers to questions that have long plagued our com-munity, including: y What bandwidth(s) must be used in the test of a new struc-ture? y How many modes must be identified within this bandwidth? y Can I identify all of these modes from a single reference test, or must I collect multiple-input multiple-output (MIMO) measurements? y Where should I place my shaker or shakers (or my reference accelerometers for a roving impact test) to achieve the best measurement results? y How many responses (or impact sites) must I measure in order to draw clear and unambiguous animations of every mode? y What is the minimum number of frequency response func-tions (FRFs) that must be measured to validate a large-scale FEM model of a new structure? y Where should these responses be measured