Consistent phase-field modeling of dynamic ductile fracture in shear-deformable curved shells

Recent advances in phase-field modeling have significantly promoted the analysis of ductile fracture in shell structures, driven by their broad applications in engineering systems. However, despite this growing interest, most existing formulations still rely on simplified shell kinematics that neglect transverse shear effects, limiting their reliability in moderately thick shells and in capturing mode III-dominated failure mechanisms. This omission restricts the sliding motion of the shell, resulting in an artificial stiffening of the structural response when such effects are not properly accounted for. To overcome this limitation, this study presents a consistent phase-field framework for the dynamic analysis of ductile fracture in curved shell structures, in which transverse shear strains are consistently incorporated into both the shell kinematics and the constitutive formulation. A refined alternating minimization algorithm is further developed to effectively address the coupled material and geometric nonlinearities arising in dynamic fracture processes. In addition, a modified plane-stress projected von Mises fracture model is introduced to consistently enforce the plane-stress condition within the adopted shell approximation. Numerical benchmarks demonstrate the robustness and accuracy of the proposed framework, showing good agreement with the available quantitative and qualitative experimental observations.