Predicting Assembly Effective Mass from Two Component Effective Mass Models

Abstract

Effective mass models are powerful tools that allow for a convenient means to calculate the energy associated with vibration response of a structure to a base input acceleration in a particular direction. This is useful for hardware qualification activities and margin assessment. Traditionally, these models are generated from purely analytical means such as a finite element model. However, experimental methods have recently been introduced as an intriguing alternative, particularly for applications where no finite element model is available. In this work, an effective mass modal model of a cable-connector assembly is desired, and neither component has a finite element model. Moreover, there can be multiple cable-connector combinations making analytical modeling as well as explicit testing of each combination impractical. This work develops the capability to combine an experimentally derived connector effective mass model with a simplified and easily extensible analytical cable model. The experimental connector effective mass model is generated through specialized modal testing. The simplified cable model is a Timoshenko beam finite element model whose properties are empirically derived from pinned-pinned cable modal data. The modeled length of the cable is appropriately adjusted for each configuration. Finally, the cable and connector component models can be combined to form the final assembly modal effective mass model for a given translational direction. This method lends itself to developing catalogues of connector and cable data, which can then be easily combined to form any number of assembly configurations without having to explicitly test/model them.