Anisotropic Elastic Constants of Copper Thin Films: RUS/Laser and Picosecond‐Laser Ultrasound
We propose a combination of the RUS/laser method and picosecond‐laser ultrasound method for measuring anisotropic elastic constants of thin films. The RUS/laser method determines the in‐plane moduli, C11, C12, and C13, of thin films; and picosecond‐laser ultrasound method determines the out‐of‐plane modulus, C33. Therefore, their combination enables us to evaluate elastic anisotropy of thin films. In this study, we measured the elastic constants of copper thin films. They showed elastic anisotropy between the in‐plane and out‐of‐plane directions. This is attributed to columnar grain structure and noncohesive bonds aligned at the columnar grain. This view is supported by micromechanics calculation.
Abstract The inelastic response of primary containment to a high-energy axisymmetric excursion is found by numerical techniques. First, the equation of state of inelastic behavior is discussed. Then the basic conservation laws of mass, momentum, and energy are given in Eulerian coordinates. These equations are then transformed into Lagrangian cooridinates and the finite difference equations for numerical computation. Finally, the results of a sample problem calculation are given.