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Essais & Simulations n°104-105

  • Text
  • Virtual
  • Imulations
  • Ssais
  • Octobre
  • Mesure
  • Novembre
  • Simulation
  • Vibration
  • Contraintes
  • Essais
Dossier : Essais virtuels

Essais

Essais virtuels DR Figure 7: the structure of the virtual vibration test system. DR Figure 6: the flow chart of the sinusoidal vibration control system. The voltage of the drive signal is: (5) The drive signal is modified until the response equal the start level by Eq.(2)~Eq.(5). DR Figure 8: the virtual vibration test system of the shaker. DR Figure 9: the computational curve of the driver. (6) The voltage of the drive signal is: (9) While the ⎢∆a n ⎢ less than 10 -5 , the level is fit, begin the vibration test. The controller outputs the drive signal to the power amplifier, and gets the response signals from the filter and the amplifier. The next frequency is calculated and is compared with the max frequency. If the frequency is not until the max, the new drive signal’s amplitude is calculated by the system transfer function, compression speed, scan rate and other parameters, and to continue the test. The process is: Calculate the error of the frequency, the a c (f n ) is the average response of the control points. (7) The expecting response at the next frequency is: (8) While the frequency is greater than the max frequency, end the test. Simulation method of the vibration test system According to the simulation methods of the various subsystems, the virtual vibration test system is assembled by the 5 subsystems. Figure 7 shows the structure of the virtual vibration test system include every subsystem, every software, every signal. The analysis results need to compare with the test results. According to test data, the system is modified. The virtual vibration test can prefigure the test results. The results are very close to that of the real test. The virtual vibration test of the shaker Application of the virtual vibration test system, the empty shaker was tested (see Figure 8). The test condition is 0.2g vertically, the frequency range is 5 ~ 500Hz. DR Figure 10: the control curves of the virtual testing vs. the true testing. Figure 9 shows the voltage of the drive signal to the power amplifier. Based on the test condition, the control curve of the virtual test is quite closed to the true test (see Figure 10). Figure 11 shows the point a15, a19 vertical acceleration response curves of the virtual test and the true test. The old curves are for the open-loop analysis 2 , the new curves are for the closed-loop analysis. From the figure we can see that the calculated curve at low frequencies more consistent with the test curve by 5~100Hz, the error is less than 15%; the calculated curve at high frequency error is greater. At the high frequency, the error E SSAIS & S IMULATIONS ● OCTOBRE, NOVEMBRE, DÉCEMBRE 2010 ● PAGE 24

Essais virtuels DR a15 Figure 11: the a15, a19 acceleration response curves of the virtual testing vs. the true testing. a19 Bibliographie [1] Xiang Shuhong, Yan Tingfei, Qiu Jibao. Research on the computer simulate technology of vibration virtual environment for tests about 40T shaker. Journal of Astronautics 25,375- 380(2004). [2] Xiang Shuhong, Liu Chuang. “Virtual vibration test and verification for the satellite”. The Fourteenth International Congress on Sound and Vibration, 2007. [3] Xiang Shuhong, Yu Dan, Yan Tingfei. “Some key technique of dynamic virtual test for safellites”. Spacecraft Environment Engineering 19, 13-22(2002). [4] Klenke S. and Baca T. “Structural Dynamics Test Simulation and Optimization for Aerospace Components”. Proceedings of the Second Test and Evaluation International Aerospace Forum, June 1996, pp.82-89. [5] Clarence W. de Silva. “Vibration and Shock Handbook”. Taylor & Francis Group. 2005. DR DR Figure 12: the virtual vibration test system of a satellite centre tube. Figure 14: the control curves of the virtual test vs. the true test. of the closed-loop method is less than that of the open-loop method. This indicates that the virtual test method has greatly improved at the high frequency. The virtual vibration test of the satellite centre tube Application of the virtual vibration test system, a satellite centre tube was tested (see Figure 8). The test condition is 0.8g vertically, the frequency range is 5~100Hz. Figure 9 shows the control points average acceleration response to 0.8g. Based on the test condition, the control curve of the virtual test is quite closed to the true test (see Figure 10). DR DR Figure 13: the computational curve of the driver. Figure 15: the PA3Z acceleration response curves of the virtual test vs. the true test. Figure 11 shows the PA3Z vertical acceleration response curves of the virtual test and the true test. The two curves are agree well except 40~50Hz. Analysis the centre tube, there is the 2 nd mode at 40~50Hz. The FEM of the tube could be modified in the future. Conclusion The system contains ALL of the subsystems in the vibration test. The virtual vibration test can prefigure the test results. The procedures of the virtual tests are the same as the real tests. The numerical results are compared with those from the real test, and the results show that the two of them are agree well. Résumé Les essais de vibration virtuels servent à prédire les résultats d’essais pour le donneur d’ordre de l’essai. Dans cet article, tout d’abord, le système moyen d’essai en vibration est présenté. En analysant le système moyen d’essai de vibration, on aboutit à une division en 5 sous-systèmes. La méthode de simulation permettant de réaliser un essai de vibration virtuel est déterminée par la prise en compte de l’ensemble des caractéristiques de chaque sous-système. Ensuite, le modèle de l’excitateur et celui du système de contrôle sont présentés. Enfin, la connexion du Modèle élément fini du satellite est faite avec la plateforme virtuelle de vibration. Une série d’essais virtuels ont été réalisés suivant cette modélisation. Les procédures pour les essais virtuels sont les mêmes que celles des essais réels. Les résultats numériques des essais réels et des essais simulés sont comparés, et cette comparaison montre une bonne corrélation. Ceci permet de dire que les essais virtuels sont très importants pour préparer efficacement une campagne d’essais de satellite. The system and platform will be more important in the satellite development ● LIU Chuang (1) , XIANG Shu-hong (1) , FENG Yao-qi (1) (1) Beijing Institute of Spacecraft Environment Engineering, Beijing, China. E SSAIS & S IMULATIONS ● OCTOBRE, NOVEMBRE, DÉCEMBRE 2010 ● PAGE 25

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