2006 Volume 37 Issue 1 Pages 3-9
To develop a random vibration test method based upon actual transport condition and susceptibility of the product against the vibration, validation of obtaining the power spectrum density (PSD) by using a low cost vibration logger and design method of PSD were investigated.
A low cost three dimensional vibration logger (interval recording type) was subjected to the sinusoidal vibration in vertical direction by using a three dimensional vibrator. PSD data obtained by equipped software gave the lesser level of power in the low frequency range due the limitation of the resolution of frequency. Therefore, in the PSD evaluation by digital Fast Fourier Transformation, attention should be paid not only for the upper limit frequency based upon sampling theory but also for the lower limit frequency.
To obtain PSD for the simulated transport test, a simple average of the PSD data will give too little power level, whereas selection of the highest level PSD will give the over power level. It is possible to obtain a PSD data which is being considered the damage susceptibility of the product by using a S-N curve. More over, an accelerated test, shortening of the time for the vibration test than the actual transport, is possible by using the S-N curve.
