4.4
Test Time from Adjusted Beta Distribution (Col. D) – Same as paragraph 3.4.
4.5
Actual Test Time (Col. E) - Same as paragraph 3.5.
4.6
Total g-rms of Tone ASD(Avg) (Col. F) – Same as paragraph 3.7, except the g-rms comes from the ASD(Avg). The average ASD is used for sinusoidal data to prevent artificially high standard deviations from affecting the final test levels. If a spectral spike is truly sinusoidal, the standard deviation at the frequency of the spectral spike should be nearly zero. However, for ground vehicles, fluctuations in vehicle speed can result in errors in standard deviation calculations as the spectral spikes move with vehicle speed.
4.7
Sine G-Peak (Col. G) – For sinusoidal data, the g-rms values of Column F are simply converted to g-peak levels by multiplying by .
4.8
Sine Peak Adjusted to Test Time (Col. H) - The g-peak level of Column G is adjusted using Equation 9.1 to account for the differences in the scenario time (Column D) and the actual test time (Column E). A slope of m=6.29 is generally used when the units are in g-peak.
4.9
Sine Test Level (Col. I) - The g-peak levels of Column H are scaled by a conservatism factor, generally 1.2, resulting in the sine test levels of Column I. The conservatism factor is intended to account for variations in level due to differences in road conditions, road conditions not considered, drivers, pilots, weather conditions, and other relevant variables. These are the final sine test levels that will be included in the LVTS.
4.10
Max Displacement (inch Pk-Pk) (Col. J) – This is the displacement in inches, peak to peak, for a sine tone with a frequency of Column C and a level of Column I.
4.11
Displacement Warning (Col. K) – If the displacement calculated in Column J exceeds a user defined level, typically 1.5 inches, the analyst is flagged by this column.
4.12
Max Velocity in/sec (Col. L) – This is the maximum velocity resulting for the given test level. Care should be taken to assure the velocity levels do not exceed hardware capabilities.
4.13
Raw Data Velocity (Col. M) – This is the velocity based on the raw data measured in the field. This is provided to the analyst as a comparison point to the final velocity.
4.14
Ratio Adjusted Peak to Peak (Col. N) – This column is the ratio of the “sine peak adjusted to test time” to the “Sine G Peak” (Column H / Column G). This is to assure that excessive exaggeration has not been applied. Observe that commercially available vibration control systems currently restrict sweep rates to be either linear or logarithmic which, unfortunately, is generally not typical of most mission scenarios (i.e., refer to the shape of the speed distribution produced by a beta distribution). Forcing the sine tones to sweep in either a linear or logarithmic manner will require magnitudes to be modified via Equation 9-1 as discussed in Annex F, paragraph 9. The analyst will need to be cautious in addressing the amount of time compression during this process. Column O in the example spreadsheet provides a quick visual check of compression employed in development of the narrowband portion of the spectrum.
4.15
Ratio Check (Col. O) - If the ratio if Column N exceeds a user selected factor, a flag is set in column O warns the analyst. Exaggeration limits are discussed in Annex F, paragraph 9. In the event the ratio check indicates excessive scaling it may be helpful to divide the LVTS into multiple LVTS that each sweep over some portion of the full range. This will allow adjustment of the distribution of time into the separated ranges, but will increase the number of LVTS’s required to represent the LCEP of interest. Additional information on this topic can be found in paragraph 3.12.