| A Stirling cryocooler has severe vibrations when it works, affecting its normal work. In view of this situation, as well as considering issues such as the installation space, the dynamic absorbers programs are proposed. Therefore sheet metal dynamic absorbers are designed upfront for the main vibration frequency of60Hz. After installation and debugging, the Stirling cryocooler’s frequency of main vibration of60Hz can be controlled well, but the sheet metal dynamic absorbers life is short, and the sheet spring ruptures after use for some time.Aiming at the problem of sheet spring fatigue life and how to improve it, this paper makes some studies. Firstly, the paper elaborated the relating theory of basic theory of dynamic vibration absorber and fatigue life, and provides the theory basis for the later the improvement of the sheet metal dynamic vibration absorber.Secondly, in order to find out the reasons of the sheet metal spring fatigue fracture, the stress analysis and the dynamic analysis are carried on in the Ansys finite element analysis software workbench (modal analysis and harmonic response analysis). The stress distribution shows that the root of sheet metal spring stress concentrated largely, and this is the main cause of fatigue damage; Dynamics calculations indicates that, the early design of dynamic vibration absorber first-order natural frequency is60Hz, meeting the damping requirements theoretically.Then, focusing on the sheet spring arc transitional area stress concentration problem, a new type of plate spring is designed, and the improved schemes about the spring materials, processing technology and post-treatment are proposed. The finite element analysis is also carried on the improved dynamic vibration absorber showing that the modified dynamic vibration absorber is better improved than the one before modification.Finally, in the laboratory, experiments were done to verify the improved dynamic vibration absorber and the before one. The natural frequency, damping performance and fatigue properties are tested by experiment. However, owing to time constraints, the improved dynamic vibration absorber is processed. Therefore, the related experiments are carried on the old dynamic vibration absorber. Later will complement the experimental study on the improved dynamic vibration absorber.At last, fatigue life comparison analysis is carried on the new plate spring and the improved dynamic vibration absorber by Ansys workbench. The results show that the improved dynamic absorbers life has been greatly improved, and achieved the expected goals. |
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