Diaphragm rupture dynamics within shock tubes: Experimental and numerical studies of the quatrefoil pattern

Understanding the rupture behavior of thin metallic diaphragms with scribed features is critical during high strain rate applications. This study examines the dynamic failure mechanisms of 1.7 mm thick aluminum AA8011 diaphragms with a cruciform scribe, emphasizing the relationship between scribe geometry, material deformation, and fracture propagation. A series of shock tube experiments were conducted on the diaphragms to characterize rupture patterns, strain distributions, and petalling behavior. A 3D numerical model was developed using ANSYS Explicit Dynamics® to replicate the observed failure phenomena. The simulations demonstrated strong agreement with experimental observations, accurately capturing the onset of plastic deformation, evolution of stress fields, rupture initiation, and the progression into a characteristic quatrefoil fracture pattern. The use of the Johnson–Cook damage model enabled the prediction of rupture onset. Furthermore, the simulations offered detailed insights into strain localization, energy dissipation, and the role of scribe depth in influencing rupture symmetry-factors that are typically difficult to quantify experimentally. These results enhance the understanding of localized failure mechanisms in scribed thin metallic diaphragms and support the development of predictive tools for optimizing rupture control under dynamic loading conditions.