A new delamination making technique for cured glass/epoxy samples and validation using vibration characteristics

In this study, a new technique using mechanical pull-up for making delaminations in cured glass/epoxy samples is proposed and demonstrated. During the development of the technique, the vibration characteristics for delaminations made by conventional PTFE inserts approach as well as the pull-up technique are compared. Firstly, the vibration responses are measured for samples with PTFE inserts. In the second stage, the vibration responses are measured after a mechanical pull-up process at the location where the PTFE is inserted. The measurements of the vibration characteristics of the intact sample are also included in the study. A unique feature of a delamination that has been properly made, that is a proper or true delamination, is a local delamination mode of vibration. This mode has been found from experimental measurements for near surface defects that were made by the mechanical pull-up process, while no such effect has been found for conventional PTFE inserts under the same experimental conditions. To further support the study, finite element analysis has also been employed to simulate an ideal delamination case. The FEA results show good agreement with experimental results for the delamination cases investigated.