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Harris' Shock and Vibration Handbook Part 5

Tham khảo tài liệu 'harris' shock and vibration handbook part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TRANSIENT RESPONSE TO STEP AND PULSE FUNCTIONS 8.43 FIGURE 8.30 Pulse consisting of vertical rise followed by exponential decay of infinite duration. FIGURE 8.31 Time response to the pulse having a vertical rise and an exponential decay of infinite duration Fig. 8.30 for the particular caseco a 2. FIGURE 8.32 Spectra for maximax response and for asymptotic residual response amplitude for the pulse shown in Fig. 8.30. FIGURE 8.33 Pulse formed by taking the difference of two exponentially decaying functions. . aelan 1 0 2 o 2 2 za . a 2.a . a 1 GW e - COSOM - 1 - sin ửnt 0 0 n J ữn Vr e a try I Cb a S.47 8.47c The maximum value of Vr occurs in the case o 1 and is given by v max 2 1.36 FIGURE 8.34 Pulse formed by taking the product of an exponentially decaying function by time. Both of the excitation functions described by Eqs. 8.4 and 8.47a include finite times of rise to the pulse peak. These rise times are dependent on the exponential decay constants. 4. The rise time may be made independent of the decay by inserting a separate rise function before the decay function as in Fig. 8.35 where astraight-line rise precedes the exponential decay. The response-time equations are as follows 8.44 CHAPTER EIGHT FIGURE 8.35 Pulse formed by a straight-line rise followed by an exponential decay asymptotic to the time axis. FIGURE 8.36 Pulse formed by a straight-line rise followed by a continuous exponential decay through positive and negative phases. Frankland. Pulse rise era ữnt- sin ữnt ữnt-ị 0 r ii 8.48a Pulse decay era eaV a2 ct 2 1 a2 con2 1 a2 o 2 sin cOnii _ COSCO COn i a B 1 - cosoy-i ._. . 7 - sin co 1 a oy ũnt1 8.486 where f t-ti and 0 t . 5. Another form of pulse which is a more complete representation of a blast pulse since it includes the possibility of a negative phase of pressures shown in Fig. 8.36. It consists of a straight-line rise followed by an exponential decay through the positive phase into the negative phase finally becoming asymptotic to the time