Experimental Research On The Mechanism Of Micro-vibration Transmission In Connecting Structures

The micrometeorite impacts in outer space and solar system radiation pressure constituted a complex environmental background factors. In addition to these there are other factors such as attitude maneuvers, satellite orbit, load startup and shutdown. All this factors result in corresponding satellite dynamic response. This process is called micro-vibration disturbances. It means frequency is as much as 1000 Hz, and amplitude is less than 10-1g.Bolted and bonded connections are widely used in spacecraft structure, and it is of great significance to study the dynamics of bolted and bonded structure in the process of transferring micro-vibration. In early Kinetic study, people often regard interface as rigid contact. In other word, there is no relative motion. But in further study, it was founded that the bolt and resin are the major sources of passive damping and stiffness in spaceship platform. They can affect the natural frequencies, modal and damping, which exhibit nonlinear mechanical characteristics. Therefore, it’s important to study the bolt connection structure and adhesive bonded structures.According to the previous macro-slip, micro-slip theoretical foundation, a dynamic model of bolt connections was established. And that the energy dissipation formulation of bolt structure were conducted, I also obtained the force-displacement analytical expression. Using MATLAB, I obtained the hysteresis loop graphics. By taking different pressure model into consideration, I finally obtained the relationship between energy consumption and exciting force and energy consumption and relative displacement.In order to obtain the corresponding modal parameters of the processing specimen, For example,getting the natural frequencies, mode shapes and the damping of structure, I took some empirical modal analysis on the processed Specimens.According to the previous theoretical analyses, I also do some experimental research on the corresponding sets of bolt connection structures and adhesive bonded structures. During the experiment, use the shakers to provide external excitation force. Force sensor, acceleration sensor, LMS data acquisition system are used in the experiment. They are used to collect, analyze the corresponding signals. Throughout the process, by varying the different torque, frequency and excitation force, I compared experimental tests on different specimens. Eventually I get acceleration data and force data under the different experimental conditions. By using the Origin software, I had done some integral operation on the acceleration data to obtain the displacement data. And then organize the data. And I can get the corresponding energy-motivation force image and energy-motivation force image on bolts and glued connection structures. These results were compared with the above-mentioned theoretical formula. In the end, I draw the final conclusions.