## Publica

Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten. # Nondestructive determination of mechanical properties

**Abstract**

The propagation velocities of ultrasonic waves are determined by the density and the elastic constants of the material under consideration. The changes of sound velocities with applied or residual stress are caused by changes of the interatomic potential, resulting in changes of the elastic behavior. Based on the nonlinear elasticity theory, Hughes and Kelly (1953) described the stress dependence of the ultrasound velocities in terms of second and third order elastic constants. It is evident from the introduction of the third order elastic constants, that these constants are more sensitive to the changes in the elastic behavior than the second order Young's - and shear moduli. The purpose of this investigation is to study the sensitivity of the acousto-elastic constant to changes in the microstructure. The knowledge of this constant is extremely important to the evaluation of stress states using ultrasonic techniques. In particular, one acousto-elastic constant was determined in Al-all oys containing different amounts of solid-solution phases and was correlated with the yield strength and the hardness of the material. The second objective is to prove the possibility to determine some mechanical properties of the material under consideration by measurements of the acousto-elastic constants.