b'Aerospace & Defense | Engineer Innovation-60FRF Sum [g/N]Correlation accuracy Real & Reciprocal modes Measured (reference) - Synthetized with Polymax 91.7% Synthetized with MLMM 97.5%-110Frequency [Hz]Figure 2: Improvement of FRF curve fitting with the MLMM modal techniqueWith the introduction of the MLMMA typical scenario is when many sensors (Maximum Likelihood Modal Model)and exciters are used at the same time algorithm into the Simcenter Testingduring a vibration test, which can cause Solutions portfolio, Siemens is makingissues in the modal estimation process. modal testing easier and more accessibleBy using the MLMM optimization, this is to non-expert users, built on top of theautomatically solved, and the local current modal testing process. Startingdynamic behavior is better represented. from a set of measured vibration data,In the example shown in figure 2, where the MLMM algorithm automaticallymodes are extracted during a GVT on a iterates on the parameters of the modalcomplete aircraft, the correlation model to improve its accuracy and the fitbetween measured FRFs (frequency to the experimental data for allresponse functions) and FRFs measurement positions and for thesynthesized with the modal parameters frequency range of interest. This allowssignificantly increases, especially in the the user to get rid of the lengthy andcase of real and reciprocal modes. tedious manual iterations. Thanks to MLMM, a more consistent Not only that, MLMM brings extramodel is obtained, which can then be accuracy in terms of resonant frequencyused with higher confidence during the and damping estimates and acceleratesaircraft verification process, while processing tasks when dealing with akeeping the existing testing processes higher level of complexity of measuredunchanged. Regardless of whether the structures, allowing non-expert users totest involves simple or complex modal deliver more consistent data. Thescenarios, MLMM is a useful technique improvement of the modal modelto improve the way modal testing is accuracy with the MLMM algorithm isperformed and help test engineers especially remarkable when constraints,achieve better results faster. With the such as reciprocity or non-complexity,new MLMM technique, modal testing are imposed on the modes in view ofhas never been so easy. nfinite element model correlation. 91'