FORCE-BASED ACCELERATION SPECTRA FOR VIBRATION TESTING OF SPACEHARDWARE

摘要

In random vibration testing of space hardware thepayloads or components in many cases have to bevibrated separated from its flight mounting structure.The difference in interface stiffness between the rigidvibration shaker and the flexible flight mounting lead toa well know phenomenon of over-testing.The National Aeronautics and Space Administration's(NASA's) Jet Propulsion Laboratory (JPL) hasdeveloped the Force Limited Vibration (FLV) methodthat reduces the over-testing by measuring the interfaceforces and using this signal in the control loop for theshaker.This paper provides an overview of the over-testingphenomenon. The simple two-degree of freedom systemnormally used to introduce the basic concepts iscompared with the more realistic multi-degree offreedom systems.The paper then presents a procedure to apply the samebasic concept of force limiting to the cheaper andsimpler classic accelerometer-controlled testingmethodology. Force-based acceleration spectra derivedwith FEA tools are used to avoid the over-testing bykeeping the interface force in the shaker to the levelsexpected during flight. The procedure can be consideredas a systematic approach to define notched accelerationspectra based on interface forces.This paper further discusses the applicability andvalidation of this methodology. Finally it presentsexamples of the usage of this methodology in actualESA space hardware currently under development.