Hole/crack identification by static strains from multiple loading modes

A method using static strains measured from multiple loading modes for the identification of holes and cracks in linear anisotropic elastic materials is introduced. Because of the localized effects of holes/cracks, their existence may not be clearly reflected by a single set of remotely measured boundary strains. By the combining of the concept of multiple loading modes with the technique of nonlinear optimization, several examples of hole/crack identification have been done. During the iteration procedure, the values of the static strains corresponding to the assumed hole/crack geometry and location are obtained by using a recently developed boundary element, which is for linear anisotropic elastic materials and has also been extended to piezoelectric materials. The identified results show that our method for hole/crack identification is stable and accurate for the model problem considered and shows that the method has promise for more complex problems. In addition, the generality of hole profile, the tolerance of measurement error, the spacing and arrangement of sensors, and the flexibility of multiple loading modes are all discussed in detail.