Research On Vibration Reduction Performance Of Mg-13Gd-4Y-2Zn-0.5Zr Rare Earth Magnesium Alloy Shell Component

Vibration and noise are fatal flaws in submarines.The development and use of high-strength and high-damping materials can effectively reduce the structural vibration and noise of the submersible.There are rare theoretical and practical studies on the combination of thermal processing and engineering applications of the medium and high strength magnesium alloys commonly used in the Engineering.In this paper,the Box-Behnken method was used to optimize the design of solid solution and aging heat treatment to improve the vibration performance of the high strength Mg-13Gd-4Y-2Zn-0.5Zr magnesium alloy.Furthermore,the finite element simulation and vibration test about the vibration amplitude of the submersible thin-walled shell components made by 5A05 alloy and Mg-13Gd-4Y-2Zn-0.5Zr magnesium alloy under different frequencies were carried out.The results can provide theoretical basis and data support to promote the application of high strength and high damping magnesium alloys in underwater submersibles.The main conclusions and innovations are as follows:(1)Tensile strength and damping coefficient were selected as the evaluation indexes in the heat treatment optimization design.According to the obtained optimized process parameters,the heat treatment verification experiment was carried out to further determine the optimal process of the heat treatment system: 520?×10 h+239?×22 h.The actual tensile strength of Mg-13Gd-4Y-2Zn-0.5Zr alloy reached 346.78 MPa,and the damping coefficient reached 0.296,which was 73.1% higher than that before heat treatment.There is good agreement between the verification experiment and the Box-Behnken prediction.(2)It was found that the damping capacity of Mg-13Gd-4Y-2Zn-0.5Zr alloy was mainly related to the area ratio of precipitated phases.When the area of the precipitated phases is larger,the movement of dislocations in the alloy is more difficult,and the damping property of the alloy is lower.Compared with the lamellar and bulk LPSO precipitates,the short rod-shaped LPSO precipitates in the alloy can effectively improve the damping properties of the alloy.(3)It was concluded that by harmonic response analysis that the vibration damping effect of magnesium alloy thin-walled cylindrical member was better than that of the aluminum alloy and the vibration response on the side was more obvious under axial excitation;the vibration damping effect of magnesium alloy thin-walled cylindrical member was better than that of the aluminum alloy and the vibration response of cylindrical member on the side and center was significant under radial excitation.(4)Under the condition of vertical vibration,there was no significant difference between the vibration amplitude of the same volume of the aluminum alloy structural member and the magnesium alloy structural member when the measurement point was at the center and the vibration frequency was less than 600 Hz.There was a small vibration amplitude and the average amplitude was reduced by 21.4% for he magnesium alloy structure when the vibration frequency was bigger than 600 Hz.There was no significant difference between the vibration amplitude of the same volume of the aluminum alloy structural member and the magnesium alloy structural member when the measurement point was at the edge and the vibration frequency was less than 400 Hz.There was a small vibration amplitude and the average amplitude was reduced by 16.2% for he magnesium alloy structure when the vibration frequency was bigger than 400 Hz.For the same quality of the aluminum alloy structural member and the magnesium alloy structural member,the vibration amplitude of magnesium alloy member was much smaller,the average amplitude was reduced by 88.5%,and the vibration damping effect was obvious.The conclusion was similar to the simulation results,and the reliability of the simulation results was verified.