This paper introduces a novel linear composite curvature MITC3+ flat shell element, named κMITC3+, that combines the advantages of the MITC3+ theory for flexural (bending and shear) behavior and the Allman-like triangular element (which ensures a true rotation of drilling degrees of freedom and eliminates a spurious energy mode) for membrane behavior. To enhance the bending behavior of the MITC3+ approach, we propose an assumed composite curvature field that is constructed using a polynomial projection technique derived from the orthogonality condition of the compatibility equation in the Hu-Washizu principle. Since two additional internal cross-section rotations are interpolated by cubic bubble functions, a linear polynomial function of the admissible space is chosen that provides a significant enhancement of bending behavior. The κMITC3+ element successfully passes all critical tests and exhibits superior performance compared to the original MITC3+ element and the recent CS-MITC18+ element.

本文介绍了一种新型线性复合曲率MITC3+平壳单元，命名为κ MITC3+，它结合了MITC3+弯曲（弯曲和剪切）行为理论和类奥尔曼三角形单元（确保钻进角度的真实旋转）的优点。自由度并消除了膜行为的杂散能量模式）。为了增强 MITC3+ 方法的弯曲行为，我们提出了一个假设的复合曲率场，该复合曲率场是使用从 Hu-Washizu 原理中兼容性方程的正交条件导出的多项式投影技术构建的。由于两个额外的内部横截面旋转是通过三次气泡函数插值的，因此选择了允许空间的线性多项式函数，以显着增强弯曲行为。κ MITC3 + 元件成功通过了所有关键测试，并且与原始 MITC3+ 元件和最新的 CS-MITC18+ 元件相比表现出卓越的性能。