Ultrasonic Inspection

"Structural integrity is driven primarily by the mechanical properties of materials which include elastic properties such as Young’s modulus, shear modulus, and Poisson’s ratio, along with material strength properties including failure strain, failure stress, and also material density. For anisotropic materials these properties, except for density, are dependent on direction. Thus, the number of elastic and strength properties of the material are increased proportionate to the number of planes of symmetry (Ross, 1980). For materials that are heterogeneous, such as fiber reinforced plastics or particulate filled polymers, additional material characteristics and properties must be included such as particle pack, binder/particle bond strength, and fiber or particle modulus and strength. If materials are viscoelastic, even more material properties must be considered including the frequency dependent viscosity and the load history of the material system of interest (Pearson and Doyle, 1994; Pearson, 1995). Clearly as the complexity of the material system increases the greater the challenge becomes to develop nondestructive evaluation (NDE) methods which can measure or correlate to properties needed for assessing material performance capabilities. Ideally, NDE tools would directly measure all these properties in support of structural integrity assurance but in practice, that is a difficult order."