Determination of constitutive parameters for predicting dynamic behavior and failure of riveted joint: Testing, modeling and validation

For aircraft structures, dynamic failure of riveted joints occurs occasionally during in-service especially when a structure is impacted by such discrete sources as birds, hailstone, etc. Due to huge number of rivets and the smaller geometry scale compared with aircraft structure, the riveted joints are usually simplified to connector elements during numerical simulations. Therefore, the proper description of mechanical behavior especially the critical failure criterion for riveted joint is of great importance. In the present work, an experimental method based on the split Hopkinson bar technique was proposed to measure the dynamic mechanical response of riveted joint at different loading speeds. By careful design of specimen and texture, the riveted joint was loaded dynamically under simple tension, simple shear and different tension–shear coupling states. Combined with quasi-static experimental results, the parameters of a constitutive equation and failure criterion for riveted joint which has been embedded in the commercial finite element software were determined. Five simplified numerical models were established to validate the failure criterion employed as well as the parameters experimentally determined. Meanwhile, two simulated bird-impact tests were conducted by using two stiffened Ti-6Al-4V plates in which the plate and the rib was connected by several rivets, and the dynamic responses were performed both experimentally and numerically for further validation. The comparisons between experiments and simulations indicate not only the proposed experimental method but also the experimentally determined constitutive and failure parameters work very well in measuring the dynamic response of riveted joint.