Random RMS is the square root of the area under a spectral density curve. Sine testing in our lab is a great … These are not equivalent. The article is a good place to start. I recently started working on Random Vibration. Several conditions were defined for which vibration could be equated on selected bases, and an interim vibration (constant period random amplitude vibration) was added between the sinus- oidal and operational vibration … NASA requirements differ however between the SV testing requirements provided in Air Force Standard SMC-S-016, Test Requirements for Launch, Upper-Stage … Often, attempts are made to compare the peak acceleration of sine wave to the root mean square (RMS) acceleration of random vibration and shock. By Harmonic response I think you are talking about a frequency response fea analysis. In this approach you get the response of a structure as a function of the frequency. The phase difference between the two sine waves refers to the difference between the phases of the waves. (Machine Design/February 6, 1992). Which one is practical in the feild ? In vibration testing, the interest is not so much the phase of an individual wave, but the phase difference between a sine wave and a reference wave. I do not have an electronic copy of this article, but if you would like I could scan it to a file and then e-mail it to you. I saw a PSD signal can be expressed in 2 ways. sinusoidal and random vibration, to seek relationships that could eventu- ally result in definition of a conversion factor for human performance from sinusoidal to random vibration. For simple sine waves the vibration frequency could be determined from looking at the waveform in the time domain; but as we add different frequency components and noise, we need to perform spectrum analysis to get a clearer picture of the vibration frequency. Fast Fourier Transform (FFT) FFT Background. Any waveform is actually just the sum of a series of simple sinusoids of different frequencies, … This paper is to discuss a mathematical method to compare … Two sine waves are out of phase when they are not at the same points in their cycles at the same time. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). Can anyone explain the major difference between sine sweep and random vibration, and how to analyze the impact on the electronic products ? Similarities in damage potential are considered in the article. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. A good article shows how to establish a random vibration profiles from swept sine tests. However, both JPL … Best Practices for Use of Sine Vibration Testing Background of SV Testing SV testing is required by NASA-STD-7002 and most launch vehicle organizations as a final dynamic qualification of the payload to demonstrate acceptability for flight. One in (G 2 /Hz) and other in ((m/s 2) 2 /Hz). Just let me know your e-mail. However, peak sine acceleration is the maximum acceleration at one frequency.