Study on out-of-plane deformation measurement using coherent gradient sensing technique

摘要

The coherent gradient sensing (C.G.S.) technique proposed by Tippur et al., Is very useful to obtain detailed information in the vicinity of a crack tip. This technique is rather easy to be applied without external disturbance and moreover can be used to any material. In the present paper, we studied various fundamental problems in applying reflection type of C.G.S. technique for evaluation of K{sub}II and K{sub}III-values. First, some fundamental points are discussed to measure out-of-plane deformation by applying this technique on cantilever beam and it is ascertained that this technique is useful to such a purpose. Next, we studied to measure K{sub}II-value and some discussions are given concerning the effects of the direction and position of the fringe too be employed for calculation of K{sub}II. Lastly, we tried to obtain K{sub}III-value by using PMMA plate under anti-symmetric four-point bending and it is shown that K{sub}III-value can be fundamentally evaluated by this technique.