In this paper. the effects of transverse cracks on rotating shaft were studied. According to earlier works. crack shaft failure decrease the critical speed of the shaft and also exhibit a nonlinear vibration behaviour leading to increases the amplitude of 1X and 2X harmonics (first and second order of rotational speed in torsional vibration). https://www.countryscenesaddleryandpetsuppliers.shop/product-category/t-shirts-2/