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I <br />N/A indicates an entire waveform was not captured and therefore no frequency could be <br />calcula[ed. More aeeura[e analysis is available using the BlastWare II I software. <br />c. Peak Acceleration <br />The Blast late III calculates peak acceleration, the rate of chan_e of velocity, by dividins the <br />difference in velocity by the difference in time. To obtain the peak acceleration, the Blasu~late III <br />subtracts two velocity readings and divides the result by the elapsed time between them. <br />_ dV DV <br />a dT OT <br />where: <br />~t = a small interval <br />The Blast~tate III calculates the peak acceleration at each point along the entire waveform and <br />reports the peak value. No[e that this is not necessarily at the peak velocity for an individual <br />waveform. <br />d. Peak Displacement <br />The Blas[~~fate III calculates peak displacement, or particle distance travelled, by multiplying <br />speed by time. to the Blas[Mate I11 the interval velocity is multiplied by the time interval and the <br />resulting displacement segments are summed. <br />s= JVdt=~,(VOt) <br />where: <br />V =the velocity in each interval <br />To obtain the peak displacement, the BlastMate III integrates each wave segment of [he entire <br />waveform between zero crossings. selec[s the largest, then divides the value by half. Note that this <br />is not necessarih at the peak velocity of the waveform. <br />e. Peak Vector Sum (PVS) <br />The figure below displays three even[ waveforms. The figure illustrates the procedure of <br />graphically calculating peak vector sums. Measured magnitudes are tabulated for six diFFerent <br />times and represent velocities in each of the three axes. The vector sum represents the resultant <br />particle velocity magnitude and is calculated by squaring and adding the magnitudes and taking <br />the square root. <br />PVS = T' + V' + L' <br />where: <br />T = particle velocity along the transverse plane <br />V = particle velocity along the vertical plane <br />L = particle velocity along the longitudinal plane <br />The Blasr~late III calculates the peak vector sum for each point of the sampled waveforms and <br />displays the largest value. Note that this is not necessarily at the peak velocity for an individual <br />waveform. <br /> <br />L J <br />Blastfvlate III Operator Manual 5-9 <br />