Dynamic failure tests on piping; Dynamic tests on straight pipe components

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Dynamic failure tests of thin-walled straight pipe components with the diameter/thickness ratio of the piping for Fast Breeder Reactor were conducted due to evaluate vibration characteristics, elastic-plastic behavior, failure mode and ultimate strength under dynamic load. The following items were confirmed by analyzing and investigating test data: (1)In accordance with input acceleration increasing, natural frequency is increased and damping rate is decreased. These are considered the effect of response reduction. (2)Although progressive deformation was observed near the fixed end of the specimens, the load-displacement behavior of the specimen was stable and fast collapse did not occur. (3)Although the specimens received much damage under dynamic load, dynamic ultimate load calculated from response acceleration is larger than static buckling load. (4)Finally, the specimens failed because cracks penetrated. As a result of SEM, the pattern like striation was observed on fracture surface, so failure mode is considered due to fatigue crack initiated inside of the wall growing and penetrating under cyclic load. (5)As a result of damage evaluation near the crack location, test data can be evaluated as the effects of fatigue and ductility consumption caused cumulative inelastic strain with progressive deformation.