Understanding vibration testing:Vib

Understanding vibration testing:Vibration testing is done by placing transducers on the power tool at the human interface locations. The power tool is then used for its intended purpose (under load) by 3 different operators while data is recorded in three orthogonal directions. The acceleration time history signals are first subjected to frequency weighting per ISO 5349-1 (this weighting is shown in Annex 1 below). The signals are then averaged into a root mean square (RMS) acceleration over the time period when the tool was engaging the work. Next, the resulting X,Y,Z acceleration directions are combined into a single vector sum (ahv). Finally, the test result is determined by averaging all of the data from the three different operators together to determine ah. An uncertainty term, K, is also submitted with the test result when the test is done for regulatory agencies.Definitions:ahw(t) = instantaneous single-axis acceleration value of the frequency-weighted hand transmitted vibration at time t, in m/s²ahw = root-mean-square (R.M.S.) single-axis acceleration value of the frequency weighted hand-transmitted vibration, in m/s²ahwx, ahwy, ahwz = values of ahw in m/s2, for the axes denoted X, Y and Z respectivelyahv = vibration total value of frequency-weighted R.M.S. acceleration, in m/s2; it is the root-sum-of-squares of the ahw values for the three measured axes of vibration ah = arithmetic mean total vibration value of the measurement results of all runs and operators in m/s2, this is the result of the testSigma R = standard deviation of reproducibility K = uncertainty of ah in m/s