Multi-Line-Beam with Variable Kinematic Models for the Analysis of Composite Structures E. CARRERA, A. PAGANI and M. PETROLO ABSTRACT In the finite element analysis of composite structures, it is a common practice to use different formulations in different sub-regions of the problem domain. In the present work, the Carrera Unified Formulation (CUF) is used to develop variable kinematic structural models. CUF is a higher-order, one-dimensional (1D), finite ele- ment formulation which was recently introduced by the first author. By exploiting the hierarchical characteristics of the CUF, a multi-line approach is developed straightfor- wardly and used for the analysis of a multilayered structure. In the multi-line method, 1D refined finite elements with different order of expansion over the cross-sectional plane are employed in different regions of the domain of the structure. Lagrange multipliers are used to ”mix” different order elements. Constraints are imposed on displacement variables at a number of points (”connection points”) whose location over the interface boundaries is a parameter of the method. The accuracy of the pro- posed method is verified both through published literature and through finite element solutions using the commercial code MSC/NASTRAN. INTRODUCTION Beam models are widely used to analyze the mechanical behavior of slender bod- ies, such as columns, rotor-blades, aircraft wings, towers and bridges, amongst others. The simplicity of one-dimensional (1D) theories, their ease of application and their computational efficiency are some of the main reasons why structural analysts prefer them to two-dimensional (2D) and three-dimensional (3D) models. The classical and best-known beam theories are those by Euler [1] - hereinafter referred to as EBBM - and Timoshenko [2] - hereinafter referred to as TBM. The former does not account for transverse shear deformations, whereas the latter assumes a uniform shear distri- bution along the cross-section of the beam. This paper is devoted to the analysis of laminated composite beams. The advan- tages of composite materials are known and, amongst these advantages, the most E. Carrera, A. Pagani and M. Petrolo, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10144 Turin, Italy.