Ireneusz Kreja

A literature review on computational models for laminated composite and sandwich panels

The present paper is devoted to a state-of-the-art review on the computational treatment of laminated composite and sandwich panels. Over two hundred texts have been included in the survey with the focus put on theoretical models for multilayered plates and shells, and FEM implementation of various computational concepts. As a result of the review, one could notice a lack of a single numerical model capable for a universal representation of all layered composite and sandwich panels. Usually, with the increase of the range of rotations considered in the particular model, one can observe the decrease of the degree of complexity of the through-the-thickness representation of deformation profiles.

Modeling of Composite Shells in 6–Parameter Nonlinear Theory with Drilling Degree of Freedom

Within the framework of a 6-parameter nonlinear shell theory, with strain measures of Cosserat type, constitutive relations are proposed for thin elastic composite shells. The material law is expressed in terms of five engineering constants of classical anisotropic continuum plus an additional parameter accounting for drilling stiffness. The theory allows for unlimited displacements and rotations. A number of examples are presented to show the correctness of the proposed model.

Linear analysis of laminated multilayered plates with the application of zig-zag function

An Equivalent Single Layer Model for linear static analysis of multilayered plates is considered in the paper. The displacements field of the First Order Shear Deformation Theory is supplemented with the Murakamis function to emulate the zig-zag effect. The applied Reissners Mixed Variational Theorem allows to assume an independent shear stress field of parabolic distribution in each layer and to satisfy the equilibrium conditions at the layer interfaces. The Finite Element implementation of the model is based on the application of the 9-node Lagrangian element with a selective reduced integration. Two numerical examples of symmetrically laminated plates are presented to illustrate the accuracy of presented approach.

Stability analysis of multilayered composite shells with cut-outs

A numerical stability analysis of an axially compressed multilayered composite shell is presented. The authors examine how the stability performance of a panel can be influenced by a centrally located square cut-out. The computations are performed within FEM computer program NX-Nastran (ver. 6.0). The stability is investigated by means of a linearized buckling analysis as well as of a non-linear large deformations incremental analysis . To get more insight into the performance of the layered structure, the failure index according to Tsai–Wu criterion is monitored in the study.

Adjoint approach sensitivity analysis of thin‐walled beams and frames

Abstract Sensitivity analysis of beams and frames assembled of thin‐walled members is presented within the adjoint approach. Static loads and structures composed of thin‐walled members with the bisymmetrical open cross‐section are considered. The analysed structure is represented by the one‐dimensional model consisting of thin‐walled beam elements based on the classical assumptions of the theory of thin‐walled beams of non‐deformable cross‐section together with superelements applied in place of location of structure nodes, restraints and stiffeners. The results of sensitivity analysis, obtained for the structure model described above, are compared with the results of the detailed FEM model, where the whole structure is discretised with the use of QUAD4 shell elements of the system MSC/NASTRAN.

Application of superelements in static analysis of thin‐walled structures

Abstract A concept of a beam superelement is suggested as a new tool in the static analysis of structures made of thin‐walled members. This proposal seems to be especially attractive for treating the problems where the existing one‐dimensional models do not provide proper solutions. This class of problems includes, for instance, the torsion of thin‐walled beams with battens and the determination of the bimoment distribution at the nodes of frames made of thin‐walled members. The entire segment of the thin‐walled beam with warping stiffener or the whole node of the frame is modelled with shell elements. The stiffness matrix of such thin‐walled beam superelement can be estimated according to the standard procedure of the enforced unit displacements. The accuracy of the proposed one‐dimensional model has proved to be comparable to that offered by the detailed FEM model where the whole structure is represented by a very large number of shell elements.