Detection of damage in cylindrical parts of carbon fiber/epoxy composites using electrical resistance (ER) measurements

The use of electrical resistance (ER) measurements of CFRP composites has been applied to investigate damage and failure in cylindrical parts such as those used in CFRP fishing rods. In this study, the ER method was used for fracture detection and to predict the final failure of cylinder-typed CFRP parts during flexural loading testing, unlikely conventional optical fiber sensor or strain gauge methods. During loading to failure the cylinder-type CFRP specimens exhibited three cracking styles. Style 1 involved the development and growth of a longitudinal crack. This was followed, in style 2, by the development of a transverse crack at the end of this longitudinal crack. Style 3 involved the occurrence of a central longitudinal crack accompanied by significant jumping of the ER change ratio during the final catastrophic failure. ER signals were consistent with visual observations of the cracking conditions of specimens during the final failure. Since the magnitude and time of the ER jumps were easily detected, such ER measurements have the potential for damage detection and prediction for other cylinder-type CFRP applications.