Application of constant curvature-corrected MITC3+ flat shell element in the analysis of rib-stiffened shell structures

This study introduces an application of constant curvature-corrected MITC3+ flat shell element, named CC-MITC3+, to analyze rib-stiffened shell structures. As an enhancement of the classical MITC3+ element, the CC-MITC3+ approach employs curvature corrections based on discrete divergence consistency within the Hu-Washizu three-field variational framework, yielding significantly improved bending behavior. In the membrane domain, an Allman-like triangular element is adopted to preserve rotational compatibility and eliminate spurious energy modes. For modeling rib stiffeners, a two-node Timoshenko beam formulation is utilized with a reduced/selective integration technique to mitigate shear locking. Through a series of numerical benchmarks, including plates and shells with varying stiffener configurations, the proposed method demonstrates superior accuracy and convergence compared to standard MITC3+ and other existing elements. These results validate the CC-MITC3+ element as a robust and efficient tool for structural analysis of rib-stiffened shell systems.