Sometimes, suddenly or gradually structural or nonstructural damages are created in structure’s members due to natural or unnatural reasons like earthquake or corrosion. One of the methods used from the early in last decade to recognize damage is wavelet transform method. In this method, instead of examination of natural frequencies and the rate of its changes, vibration response or static response of a structure in various points of a structure is recorded at the same time, which in fact is a place-domain signal. In this paper, some factors have been investigated on a plate such as the effect of crack depth reduction, effect of changing support conditions, and the effect of approaching two rectangular cracks; and the responses obtained from finite element analysis, have been studied and the following results are gained: the ability of wavelet method to recognize the locality and severity of cracks, identification of tiny cracks up to 0.5mm depth and increasing the intensification of cracks’ effect on plate by reducing their distance from each other. پرونده مقاله