HYBRID ELEMENT METHOD FOR MID-FREQUENCY VIBROACOUSTIC ANALYSIS IN MANY SITUATIONS, AEROSPACE STRUCTURES ARE…

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HYBRID ELEMENT METHOD FOR MID-FREQUENCY VIBROACOUSTIC ANALYSIS IN MANY SITUATIONS, AEROSPACE STRUCTURES ARE SUBJECTED TO A WIDE FREQUENCY SPECTRUM OF MECHANICAL AND/OR ACOUSTIC EXCITATIONS AND THEREFORE, THERE IS A NEED FOR THE DEVELOPMENT OF NUMERICAL MODELING TECHNIQUES THAT ARE APPLICABLE FOR THE RESOLUTION OF DYNAMIC RESPONSE OF COMPLEX SYSTEMS SPANNING THE ENTIRE FREQUENCY SPECTRUM. HOWEVER, THE DYNAMIC BEHAVIOR OF THESE STRUCTURES AT DIFFERENT FREQUENCY RANGE IS GOVERNED BY DIFFERENT PHENOMENA AND AS A RESULT, A SINGLE NUMERICAL SOLUTION PROCEDURE IS NOT SUITABLE FOR THE RESOLUTION OF THE ENTIRE FREQUENCY SPECTRUM. THUS, ON THE BASIS OF THE NUMERICAL MODELING TECHNIQUES, THE FREQUENCY SPECTRUM IS TYPICALLY DIVIDED INTO THREE REGIONS; LOW FREQUENCY REGION, MID-FREQUENCY REGION AND HIGH FREQUENCY REGION. THE LOW FREQUENCY REGION IS THE FREQUENCY RANGE WHERE THE CHARACTERISTIC DIMENSIONS OF ALL COMPONENT MEMBERS OF A VIBROACOUSTIC SYSTEM ARE SHORT WITH RESPECT TO WAVELENGTHS AND THESE MEMBERS ARE ALSO REFERRED TO AS 'SHORT' MEMBERS. ON THE OTHER HAND, IN THE HIGH FREQUENCY REGION, THE CHARACTERISTIC DIMENSIONS OF ALL COMPONENT MEMBERS ARE LONG WITH RESPECT TO WAVELENGTHS AND THESE MEMBERS ARE REFERRED TO AS 'LONG' MEMBERS. THERE EXISTS A BROAD MID FREQUENCY REGION IN WHICH NOT ONLY SOME COMPONENTS ARE LONG AND OTHERS ARE SHORT WITH RESPECT TO WAVELENGTHS THE PROPOSAL IS DIRECTED TOWARDS THE DEVELOPMENT OF AN INNOVATIVE HYBRID ELEMENT METHOD BY COUPLING DETERMINISTIC, TRANSITION AND STATISTICAL FINITE ELEMENT METHODS TO YIELD A SOLUTION SYSTEM THAT IS APPLICABLE FOR THE SOLUTION OF FULL FREQUENCY SPECTRUM VIBROACOUSTIC PREDICTION OF NONUNIFORM AEROSPACE STRUCTURES INCLUDING METALLIC/COMPOSITE CONFIGURATIONS, ACCURATELY AND EFFICIENTLY.