Method of estimating system dynamics by subsystem transfer function testing

#The present invention relates generally to estimating system dynamics, and more particularly to a method of estimating system dynamics by measuring subsystem transfer functions of a system under test.

#The dynamic performance of a structural system composed of a plurality of subsystems, such as a space satellite including a space bus and space payload, can be significantly affected by vibration or shock. The vibration or shock can damage or alter sensitive subsystems of the structural system. The need to understand the effects of vibration and shock on a particular subsystem, as well as on the structural system as a whole, is paramount to obtaining optimal dynamic performance.

#Conventional methods perform detailed finite element modeling of all subsystems and the system as a whole in order to determine the effects vibration and shock will have on the system. Initially, a finite element model is generated for each subsystem. The subsystems are subsequently tested using shaker or tap excitation and motion (accelerometer) sensing in a free (suspended) or fixed (bolted to a surface) boundary condition. As the tests are performed, each subsystem finite model is tweaked to better match the test data in a process known as model updating. However, the model updating process provides an estimate of only limited accuracy regarding the effects of vibration and shock on a particular subsystem because the subsystem model never fully converges with the test data.

#Objects and advantages of the present invention will be more readily apparent from the following detailed description of the preferred embodiments thereof when taken together with the accompanying drawings in which:

#FIG. 1 shows a first exemplary system to be tested by a first embodiment of the methodology of the present invention;

#FIGS. 2A-2B show measured subsystem transfer functions for each subsystem of the exemplary system in FIG. 1 when test forces are applied according to the first embodiment of the methodology of the present invention;

#In overview form the present disclosure concerns structural systems designed for space travel. Examples of such systems include space buses that carry space payloads. As further discussed below various inventive principles and combinations thereof are advantageously employed to determine a dynamic performance of the structural system and more specifically to determine the effect dynamic forces applied to the space bus will have on the space payload provided these principles or equivalents are utilized.

#The instant disclosure is provided to further explain in an enabling fashion the best modes of performing the embodiments of the present invention. The disclosure is further offered to enhance an understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the invention. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

#It is further understood that the use of relational terms such as first and second, top and bottom, and the like, if any, are used solely to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions. Much of the inventive functionality and many of the inventive principles are best implemented with or in software programs or instructions. It is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs with minimal experimentation. Therefore, further discussion of such software, if any, will be limited in the interest of brevity and minimization of any risk of obscuring the principles and concepts in accordance with the present invention.