松動件定位外文翻譯--松動件位置的技術(shù)研究-資料下載頁
2025-05-11 13:56本頁面
【導(dǎo)讀】Wigner-Ville分布的撞擊信號的變化來獲得。從撞擊位置到信號測量點(diǎn)的距離可以通。過運(yùn)用反應(yīng)堆中兩個彎曲波的傳播速度，到達(dá)時間的不同來估測。提交的定位撞擊部位的方法與實(shí)際的撞擊部位比較，誤差在百分之十以內(nèi)。動件的位置及把他們從RCS中移除就顯得尤為必要。鑒于這一必要性，眾多的關(guān)于估。兩個不同的加速度傳感器測量得到的撞擊信號的衰減值。還有，olama在1985年引入。這篇論文中提及的方法運(yùn)用了金屬板中彎曲波的離散特性-金屬板中彎曲。2)的傅立葉變換，s.s*是一種附屬時間的自相關(guān)功能。為了從有限記錄長度去評估Wigner-Ville分布，公式1的。下峰值的影響，這就是反射波的最大能量。表示以1f為頻率，A，B亮點(diǎn)之間，彎曲波的傳播時間間隔。加速度傳感器分別安裝在A、B、C三點(diǎn)，并在o點(diǎn)產(chǎn)生一個撞擊。到達(dá)時間，剩余的輪廓線表示的是反射波到達(dá)A點(diǎn)的到達(dá)時間。圖片6曲線分別表示
【正文】 7,860 kg/m 3 and 200 GPa, respectively. Accelerometers are mounted at the points A, B, and C on the plate, and an impact is made at point time history of the signals measured at the impact hammer and three accelerometers are shown in Fig. 4. Contour lines of the WignerVille power distribution in timefrequency plane for acceleration signal at point A are shown in Fig. 5. The first contour line (closest to the axis of t=0 39。39。) represents the power arrival time of bending waves with various frequencies at point A. The remaining contour lines signify the power arrival time of reflected bending waves at the point A. Fig. 6 presents the power arrival time curves at points A, B, and C, which correspond to the power arrival time of bending waves at points A, B, and C. The power arrival time difference between the two bending waves at one measurement point can be obtained from Fig. 6. Also, the power propagation velocity of a bending wave can be estimated using Eq.(6) from the experiment that the impact point and two measuring points lie in , the distance from the impact location to the measurement points A, B, and C, respectively, can be estimated using Eq. (7). In Table 1, the estimated rA, rb, and rc values are shown and relative percentage error of the estimated results is within 10% pared with the actual distance. 6. CONCLUSIONS An improved method to estimate impact location of loose part using WignerVille distribution is established under the assumption that a structure has homogeneous material property and uniform thickness. When applying this method to a real structure connected with pipes, elbows, nozzles, etc., it is necessary to take into account the effect from change of material property and thickness for the real structure. Using dispersion characteristics of bending waves propagated in a homogeneous plate with uniform thickness, the power propagation velocity and arrival time difference of bending waves related to the dispersion characteristics can be obtained from the WignerVille distribution. The distance between a measurement point and impact location of a loose part can be estimated using power propagation velocity and arrival time difference between two bending waves with different frequencies at one measurement point. Experimental results for the homogeneous plate showed relative percentage error within 10% pared with the actual distance. REFERENCES Cremer L., Heckl M. (1972), StructureBorne Sound, SpringerVerlag, Berlin. Fahy F. (1985), Sound and Structural 1,7bration, Academic Press, London. Kim . and Park . (1994), WignerVille Interpretation of Musical Sound and Transient Vibration Signals, WESTPRAC 1994, 752. Kryter R. C. and Shahrokhi F. (1981), Summary o~ Studies on Methods Jor Detecting, Locating, and Characterizing Metallic Loose Parts in Nuclear Reactor Coolant System, U. S. Nuclear Regulatory Commission Report NUREG/CR2344. Olma B. J. (1985), Source Location and Mass Estimation in Loose Parts Monitoring of PWRs, Prog. Nucl. Energy 15,583. Ville J. (1948) Theorie et applications de la notion de signal analitique. Cables et Transm., 2A(1), 6174 Wahl T. J. and Bolton J. S. (1993), The Application of the Wigner Distribution to the Identification of StructureBorne Noise Components, J. Sound and Vibration 163(1 ), 101. Wigner E. (1932), On the Quantum Correction for Thermodynamic Equilibrium, Physical Review 40, 749
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