1 MIL-STD-810D Downloaded from https://www.everyspec.com 19 July 1983 Figures 514..3-1thru 514.3-3 depict the common carrier environment. These figures are based upon data measured at the cargo floor of seven different configurations of trucks and tractor-trailer combinations. Both conventional suspensions and air-cusioned suspensions are represented. The data was, collected from typical interstate highways with rough portions as part.of .. the data base. ,,. . Figures 514.3-4 thru 514.3-6 represent the cargo environment at the floor of the M105 two-wheeled trailer. The data include differing vehicle load conditions traversing over sDeciall~ desimed courses ranging from vaved .
highway to offroad c~ndition~ at va;ious ~ehicle speeds. ‘As-seen, ~he spectrum is broadband random with peaks and notches at varioua discrete frequency bands. The break points of the peaks and notchee are given for establishing the spectrum shape. Two-wheeled trailers of significantly different size and design may provide substantially different input to the cargo loaded on the bed than displayed in figures 514.3-4 thru 514.3-6 and spectra should be adjusted accordingly. ,. Figures 514.3-7 thru 514.3-9 represent the cargo environment at the cargo ,bedof a composite of tactical wheeled vehicles~ the 5-t_onM813 truck and the 12-ton Ml27-semi-trailer.
The data include differing vehicle loading conditions traversing over specially designed courses ranging fram paved highway to offroad conditions at various vehicle speeds. Again the spectrum is broadband random with peaks and notches at varioua discrete frequency bands. Break points are provided for establishing the spectrum shape. Tactical wheeled vehicles of significantly different size and design from the M813 and Ml27 may provide substantially different input.to the cargo 10aded on the bed than displayed in figures 514.3-7 thru 514.3-9 and spectra should be adjusted accordingly. Figures514.3-10 thru 514.3-22 represent the environment at the floor of the M548 tracked vehicle.
The data utilized for establishing these spectra were derived from measurements of the vehicle operating at various speeds over specially designed courses ranging from paved highway to.offroad conditions. This environment contains a low level of broadband random upon which is superimposed narrowband random at discrete frequency bands. The broadband random base is from the basic movement of the vehicle, suspension-systemand road discontinuitiea. The narrowband random excitation is associated with the track-laying pattern and road surface. b. Test dura W. t. The test duration for Basic Transportation should be based upon total miles of expected transportation.
A method for development of test durations is included in appendix 1. The common carrier spectra given in figures 514.3-1 thru 514.3-3 have a test time duration of 60 minutes per “1OOO miles. For tests which utilize the test spectra contained in figures 514.3-4 thru 514.3-22, the time durations per test axis are given on the individual figures, with the exception of the M548 Cargo Carrier. The total teet time for that particular vehicle ‘is60 minutes.per 16 miles, which consists of teeting in several phasea per axis (the test time per phase ia given on the appropriate figure) to accommodate the total swept narrowband random-on-random environment. FETHOD 514.3 19 July 1983 514.3-6