The practical use of the hole method in moiré

Abstract:

A review of the direct solution for the displacements around a circular hole in an infinite plate subjected to bi-axial loading led to two problems. Problem 1 relates to the superposition of the Kirsch solution to solve the problem of a bi-axially-loaded infinite plate with a hole; and, Problem 2 which is the residual stress problem. Next, the inverse problem or "hole method" is defined and solved only for the case where the principal stress tensor alignment coincides with that of the moiré gratings used to measure horizontal and vertical displacements. Finally, computer-generated moiré fringes show the practical application of the developed "hole method" equations for solving Problem 1 and Problem 2. This approach is applicable to geometric and interferometric moiré. There are additional problems inherent to the use of moiré for residual stress measurement that need to be addressed and overcome, such as the fact that moiré relies on a pre-oriented grating for its measurement. This is not a problem when using radial and tangential moiré gratings. Actually, the use of radial moiré gratings allows the direct determination of the principal stress directions, since they coincide with the axes of symmetry. When using horizontal and vertical moiré gratings, since the orientation of the principal strain (stress) tensor is not known before a hole is drilled on a specimen, it is almost impossible to correctly pre-align the moiré gratings. Finding a solution to this problem is basic to seeking an acceptable approach to making the "hole method" amenable to measurement by the moiré method. Copyright ©1999 Elsevier Science Ltd All rights reserved.

Año de publicación:

1999

Keywords:

Fuente:

scopus