Abstract
In order to solve the problem that the photoelectric instrument may fail when the vibration response of the truss composite structure is too large, the method of applying the viscoelastic-constrained damping layer on the truss wall and the box panel is used to reduce the vibration of the whole structure. In this article, a broken long tube with viscoelastic-constrained damping layer is introduced. The long tube of the original structure is broken into two identical short tubes, and a tube with free damping layer is added to the junction of the two short pipes, which is connected by adhesive and broken long pipe. By analyzing the frequency response of the traditional space truss and spaceflight load structure, and a broken long tube structure, the acceleration response cloud diagram and the acceleration response curve of the fixed measuring node are obtained. Experiments were carried out to verify the feasibility of the structure. The test results show that the method of broken long pipe with viscoelastic-constrained damping layer can achieve better damping effect than the traditional truss structure, and it can effectively reduce the vibration level of the space load at the end of the truss, and has important reference significant for the vibration reduction design of other space structures.
Highlights
With the development of spacecraft toward the direction of large scale and complexity, the space truss has been applied more and more widely because of its easy disassembly, good technology, light weight, and the ability to adjust the structure according to the specific needs
The low-frequency sinusoidal vibration is mainly caused by the pogo vibration, engine start, flameout, and interstage separation of the projectile structure; the low-order modal free oscillation is caused by the gust and the shock wave oscillation in the transonic flight segment; and low-order longitudinal oscillation is caused by incomplete combustion of the engine
Where hðsiÞ is the damping factor of i-order mode, hnj is the damping factor of the j-species viscoelastic material, SEji represents the r-order mode and strain energy of the j-type viscoelastic materials, SEi is the total strain energy of the mode i, and n denotes the number of viscoelastic materials. It can be seen from formula (16) that the damping factor is calculated by the ratio of the viscoelastic damping layer to the energy consumption of the whole structure by the modal strain energy (MSE) method
Summary
With the development of spacecraft toward the direction of large scale and complexity, the space truss has been applied more and more widely because of its easy disassembly, good technology, light weight, and the ability to adjust the structure according to the specific needs. The low-frequency sinusoidal vibration is mainly caused by the pogo vibration, engine start, flameout, and interstage separation of the projectile structure; the low-order modal free oscillation is caused by the gust and the shock wave oscillation in the transonic flight segment; and low-order longitudinal oscillation is caused by incomplete combustion of the engine This kind of low-frequency vibration environment will cause the space truss structure to be damaged, the connection will be loose, the structural parts will be deformed, and the performance will be decreased. The viscoelastic damping layer is applied to the space truss and space load structure for vibration reduction according to actual needs. Formula (15) shows that the damping factor h of viscoelastic damping materials is the ratio of the energy consumed by each cycle of vibration to the total strain energy. The magnitude of damping factor represents the level of damping,[21] which reflects the vibration reduction effect of the structure
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