2011 Volume 5 Issue 1 Pages 33-43
A new method for detecting delamination cracks in carbon fiber reinforced polymer (CFRP) laminates using changes in electrical resistance was developed in a previous study. It was possible to detect delamination cracks without sampling the data from intact structures and to prevent false diagnoses from changes in electrical resistance caused by damage to the electrical contacts at the electrodes. As a result of the study, delamination of at least 5.3 mm in diameter caused by a quasi-static load in a quasi-isotropic-plied CFRP plate was detectable without sampling the data from intact structures. However, the proposed diagnostic method has not yet been experimentally performed for detecting delaminations subjected to impact loads. Although it is unfortunate that there is not much difference between damage of FRP laminates subjected to low-speed impacts and those subjected to quasi-static loads, broken fibers in the surface layer and plastic deformation such as a dent accompanied by delamination might depend on the rate of strain. It is also necessary to ensure that the diagnostic method provides correct diagnoses even if impact damage of electrical contact occurs at the electrodes. The diagnosis was not affected by chipped electrodes except for through chips. The present study employs the diagnostic method for delamination cracks and damage to electrical contacts of an electrode subjected to falling weight impact loads and dents from quasi-static loads.
