Fracture analysis of welded connections

Yetgin, Ali
The main objective of this thesis is to evaluate structural integrity of a multi barrel launcher system on fracture mechanics basis by using finite element method. A global finite element model that includes necessary kinematic and elastic connections is built. Dynamic firing forces are applied on global finite element model and general structural response is obtained. Sub modeling method is used in order to perform crack analysis. Since size of global model is too large to include solid crack elements which are relatively finer, separate finite element models must be created. Therefore, sub models were created and boundary conditions were imported from the global finite element model. Firing tests of the launcher system was performed and measurements were taken from tests. Strain gage and displacement sensors were used on several locations and test results were compared with the global finite element model. After the global finite element model was verified by firing tests, sub modeling and crack modeling methods were verified against literature studies. In sub models, a critical welded connection is investigated. Three different crack configurations that are likely to occur in that region are studied. Semi elliptical surface crack at weld toe, inner surface of closed section member and embedded circular crack are modeled. Stress intensity factor values were given for those configurations and compared.
Citation Formats
A. Yetgin, “Fracture analysis of welded connections,” M.S. - Master of Science, Middle East Technical University, 2013.