Study On The Evaluation Of Lamb Wave Propagation Characteristics Of The Metal Based On Photoacoustic Fatigue

Based on the thermoelastic equation, through the analysis of the temperature field and stress produced by interaction laser and material, research physical process of laser in the surface of the aluminum plate stimulate ultrasonic. Research suggested, laser stimulate different modes of Lamb wave. Due to fatigue of sheet metal, the sheet metal internal will produce the change of elastic modulus. Lamb wave through different modulus of elasticity, the corresponding received Lamb phase will change. Through the received Lamb phase can get the fatigue degree of internal sheet, to achieve the purpose of Nondestructive Testing.Different mode of Lamb wave for the sensitive degree of different elastic modulus change, inversion of metal fatigue is also different. In order to study imaging quality of difference order mode Lamb waves, the propagation of the Lamb wave are studied by theoretical calculation and simulation experiment. It is found that the velocity shift of the high order mode Lamb wave is more sensitive to the variations of elastic coefficients than that of the low mode, and the radius of the Lamb wave is closer to the actual radius, the image quality is better than low modes.Then, high image quality can be obtained by using the high modes of Lamb wave in the analysis of image.