Experimental Investigation into the Fatigue Life of Hybrid Joints Under Fully Reversed Flexure Loading; Rept. for 1 Jun 2005-31 May 2008

摘要

Glass Reinforced Polymers (GRP's) have a variety of properties that make them desirable for use in marine applications. For instance: high strength, low weight, corrosion resistance, inherent complex forming abilities, and low electromagnetic signature characteristics can be exceedingly advantageous in such areas. The U.S. Navy currently has an objective to investigate the use of lightweight materials to enhance naval capabilities, and GRP's have been of particular interest. Composite/metal hybrid systems offer a potential solution to many of the complications encountered in the construction of naval vessels, such as the weight of materials that are currently used and difficulty of forming them. Prevention of structural failures in a ship is essential if human injury, casualties and economic loss are to be avoided. Fatigue of connections is a major concern in an ocean environment. The overall objective of this research is to develop and demonstrate methods for fatigue testing various common and novel steel/composite hybrid connections and to evaluate their suitability for their desired applications. Fatigue of hybrid connections subject to out-of-plane loading is highly variable and there is a lack of data reported in the literature. The intention of this effort is to provide additional baseline data for this type of connection. Testing and analysis techniques were successfully developed and employed. It was determined that separate analyses of the individual components of a hybrid joint (e.g. the composite plate and the steel T-section) are insufficient to determine the effects of fatigue loading on a given joint due to the effects of joining methods on the strength. Fatigue testing of a full joint configuration is necessary to adequately evaluate its response to fatigue loading. Further testing beyond what is presented in this report is recommended.