An Investigation of the Failure Mechanisms of a Polymer Matrix Composite Crew Oar

Abstract

Rowing, or crew, is a constantly evolving sport with an impressive history of equipment advancements, including the use of advanced polymer matrix composites as construction materials for boats and oars. While the use of composites undoubtedly improves the performance of the equipment, the complexity of such a material makes it difficult to establish the cause of failures observed during practice and competition. In particular, composite oars, which are ubiquitous in competitive rowing, have the potential for catastrophic failure. The present effort at investigating the failure mechanisms of a composite oar involved metallographic examinations of the fracture surface using a scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS), as well as finite element stress analyses using ANSYS software. From a cross section analysis, the fiber volume percentage of the oar was measured to be 58.2%. Finite element modelling results suggested that oar failure was not the result of a discrete load, which implies that cyclic loading and structural defects were likely the primary contributing factors. A visual fracture analysis revealed surface defects introduced due to improper handling. No chemical degradation was found in the vicinity of the fracture site; however, degradation in the form of congelifraction (freeze–thaw of trapped water) was found to be a possibility. Based on the aggregate results of this investigation, recommendations for suppliers are provided in terms of manufacturing process and for sporting organizations at large with respect to improved storage and transportation of oars to reduce the likelihood of fatigue failures during training and competitions.