MODAL TESTING AND FINITE ELEMENT ANALYSIS OF A BATTERYRACK FOR SEISMIC APPLICATIONS

摘要

One of the most challenging aspects of the reliability testing in the telecommunication industry is earthquake resis-tancerntesting. The cabinet systems, battery racks, equipment racks and distribution frames are considered as earthquakernNEBS compliant, if the maximum deflection of the top of the structure does not exceed the 3-inch limit, there are no perma-nentrndeformations or structural damage, and the equipment or batteries remain functional. Based on the seismic test results ofrna large population of the telecom enclosures, it was observed that a system always passes the seismic test, if its fundamentalrnnatural frequency is at least 6 Hz. The cost of seismic qualification testing is high, coupled with the cost of production of thernenclosure and its configuration. In order to minimize the risk of telecom system failure, it is advisable to first perform a mo-dalrnFinite Element Analysis (FEA) of the system, and subsequently, to verify the numerical results with the experimentalrnresonance search data using either modal testing or sine swept survey, coupled with the static pull testing, where applicable.rnDepending on the resonance search results, simulation of the seismic testing (seismic analysis) may or may not be necessaryrnprior to the seismic qualification testing. The paper elaborates on the key aspects of the static pull test method supported byrnthe test results for a cabinet framework and a configured cabinet relative to the seismic test results, discusses the sine sweeprntesting of a battery cabinet and the modal test results for the corresponding battery rack that were obtained using two meth-ods.rnThe last portion of the paper describes modal FEA of the same battery rack anchored to a concrete pad supported by arnstyrofoam sheet and the correlation of the numerical with the experimental modal analysis results. The correlated modelrnserves next as the baseline model for analysis of other battery racks as well as of the equipment cabinets that are also config-uredrnwith batteries.