Quality Analysis of Stress Wave Installation of Titanium Alloy Interference Fit High Lock Bolt

(College of Mechanical and Electrical Engineering, Northwestern Polytechnical University, Xi'an 710072, China) To improve structural fatigue strength, new installation methods need to be studied. The strengthening mechanism of titanium alloy interference fit and the characteristics of stress wave method for installing interference fit fasteners are introduced. Fatigue the test piece.

The thickness of the test piece is determined by the length code of the bolt, and the corresponding relationship is shown in Table 1. Table 1 Corresponding relationship between the sample thickness and the bolt length The bolt length code sample thickness / mm is completed.

microstructure.

The middle white area is a sandwich panel and the black area is a fastener. When the fastener is installed in the conventional method, the material structure of the joint surface of the fastener and the connecting plate is severely deformed, the two materials are inlaid with each other, and the connecting plate has a downward displacement; in the stress wave mounting fastener The material on the bonding surface of the fastener and the connecting plate is not inlaid with each other, and the grain of the material is refined, which is beneficial to improve the fatigue life of the joint. In addition, the stress-wave mounting method produces a residual compressive stress region in the hole wall that is significantly larger than the residual compressive stress region generated by the conventional mounting method, which is beneficial to improve the joint fatigue life. See the typical form of fatigue damage. The fatigue test results are shown in the assembled fatigue test piece. 2. Fatigue test The fatigue load is 25%~40% of the static strength of the test piece. The high load transfer joint is used, the stress ratio is 0.1, and the sine wave is loaded at a constant amplitude. The maximum frequency is The temperature of the sample does not exceed 65 C. The test machine is a PLG-50 microcomputer controlled high frequency fatigue tester. For high-load transfer specimens, the working section is subjected to a combination of tension and bending during loading, so it is necessary to use a clamp to limit its bending deformation. The test piece after the completion of the clamping.

2.3 Material Microstructure Comparison When the interference fit fastener is forced through the fastener hole, the material of the hole wall is squeezed, the microstructure of the material changes, and a residual compressive stress layer is formed within a certain range, thereby achieving the purpose of strengthening. Since the ordinary installation method and the stress wave installation method are installed with a large difference in the loading rate, the residual compressive stress layer formed is not the same. And the use of the two methods to install the fasteners and the material of the hole wall, the stress wave installation method significantly improves the fatigue strength of the joint. This aspect is due to the stress wave installation method which reduces the damage during the installation process, and on the other hand, the stress wave has a "stretching" effect on the fastener, so that this method can install a larger interference amount of the fastener. The interference amount is close to or reaches the optimal interference amount of the material, thereby improving the fatigue life of the structure.

(Continued on page 145) or a smaller initial water volume, which results in a larger exit speed and a smaller water cannon launch time.

3) From the point of view of water gun design, if you want to get an earlier atomizing jet, the barrel should be shorter, so that the outlet jet atomization cone angle will be larger, the gas-liquid action surface will increase, and the jet atomization effect will be enhanced. In order to obtain a longer range, it is necessary to increase the length of the launch tube, so that a smaller atomization cone angle and a higher velocity gas-liquid jet can be obtained. The 1.5-fold gas chamber diameter is an ideal gas chamber diameter. When the diameter is increased, the jet velocity is no longer increased, and the jet velocity is reduced.

The conclusions obtained in this paper have contributed to the improved design of pulsed riot cannons and the atomization study of gas-liquid jets.

Wang sent and so on. The application and research status of various anti-riot water cannons in police field. The Defense Branch Wang sent, and the Warren Army. Modeling and 2D simulation analysis of the pulsed anti-storm cannon launch tube. Journal of Air Force Engineering University (Natural Science Edition), 2009, 10 (4) Zhang Zhaoshun et al. The theory and application of turbulent large eddy numerical simulation. Beijing: Tsinghua University Press, 2008 Wang Chuan, Zhan Renjun. Police pulse anti-riot water cannon experimental system design. Journal of Changchun University of Technology (Natural Science Edition), 2009, 30 (2): 173-177 Zhan Renjun, Wang Yong, Wang Chuan. Design and experimental research on a nozzle for pulsed anti-storm water gun nozzle. Mechanical Science and Technology, 2010, 29 (6) Wang Chuan, Zhan Renjun. Large eddy simulation of the jet at the exit section of a pulsed riot cannon. Journal of Air Force Engineering University (Natural Science Edition), 2010, Li Wei, et al. Swelling combustion chamber flow field RANS and LES simulation. Naval aviation workers Tao Rong, Yan Liping, Zhou Jingwei. Large eddy simulation of the swirling jet flow. China Liu Ruxun, Shu Qiwang. Several new methods for computational fluid dynamics M. Beijing: Science Press, 2003 (Continued from page 140) 3 Conclusion The maximum interference of stress wave installation is much larger than the maximum interference of ordinary installations, indicating that the stress wave installation method can achieve large The amount of interference interferes with the installation of the fastener.

The stress wave installation method has a large residual compressive stress area generated in the joint hole wall, and the installation quality is superior to the ordinary installation method.

The stress wave installation method can greatly improve the fatigue life of titanium alloy joints and is an ideal installation method.

AH Yakwitz, OC West Lotkin, BA Philsov, HM Kishelev, Zhang Guoliang translation. Long-life bolting and riveting technology for aircraft. Beijing: Aviation Industry Press, 1991 Caoqiang, Liu Hong. Electromagnetic riveting technology. Journal of Plastic Engineering, 2007, (1): Guo Lanzhong, Xing Wenzhen. The preliminary discussion on the mechanism of interference enhancement. Mechanical design and manufacturing workers Gao Bin, Cao Enhanced. Interference with the installation of fasteners. Aviation Manufacturing Technology, Ministry of Aviation Industry of the People's Republic of China. HB/Z14249: Edited by China Academy of Aeronautical Science and Technology, with the amount of interference and the amount of expansion. Aircraft Structure Anti-Fatigue-Fracture Strengthening Process Manual M. Beijing: Aviation Industry Press, 1993 Tao Hua, Gong Gongyi, Sheng Xi. The stress wave mounts an interference fit fastener. Aviation

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