Elastic Behavior of Lay-Ups Angles of Laminated Composite Beam with Material Property Grading

The article discusses the study of Vibration Analysis of Generally layered Graphite-Epoxy with lay-up [300 /500 /300 /500 ]. The finite element method is utilized in the study, to analyze the effect of lay-up on the natural frequency and comparing the results with the article[1]. Method: The study is done using Ansys. Graphite-epoxy is considered for the study. The model is prepared from SHELL 281 element which is well-suited for composite shells and sandwiched construction. The accuracy in modeling composite shells is governed by the first-order MindlinReissner shell theory. The element has 8 nodes with 6 degrees of freedom at each node translations in the x, y, and z axes, and rotations about the x, y, and z-axes respectively. Finding: The study concludes that the values of natural frequency decreased when increased the difference between angles of lay-up. Novelty/Applications: Vibration Analysis study has been done in aspects, like sandwiched beam in which different materials are sandhwiched in a layer by layer fashion. Many studies also covers composite material with lay-up in great detail, but there is acute study about the comparision of the different lay-up angles at given boundary condition. These articles cover the same at a greater extent, and conclude that the strength and capacity of composite beams can be enhanced not only by blending composites together, but also giving importance to the arrangement of layers of composite materials.

Weight minimization of fiber laminated composite beam for aircraft wing construction using exhaustive enumeration algorithm and numerical modeling

Purpose This paper aims to focus on calculating the number of layers of composite laminates required to take the applied load made up of graphite/epoxy (AS4/3501-6) which can be used in many industrial applications. Optimization for minimization of weight by variation in the mechanical properties is possible by using different combinations of fiber angle, number of plies and their stacking sequence. Design/methodology/approach Lots of research studies have been put forth by aerospace industry experts to improve the performance of aircraft wings with weight constraints. The orthotropic nature of the laminated composites and their ability to characterize as per various performance requirements of aerospace industry make them the most suitable material. This leads to necessity of implementing most appropriate optimization technique for selecting appropriate parameter sets and material configurations. Findings In this work, exhaustive enumeration algorithm has been applied for weight minimization of fiber laminated composite beam subjected to two different loading conditions by computing overall possible stacking sequences and material properties using classical laminate theory. This combinatorial type optimization technique enumerates all possible solutions with an assurance of getting global optimum solution. Stacking sequences are filtered through Tsai-Wu failure criteria. Originality/value Finally, through the outcome of this optimization framework, eight different combinations of stacking sequences and 24-ply symmetric layup have been obtained. Furthermore, this 24-ply layup weighing 0.468 kg has been validated using finite element solver for given boundary conditions. Interlaminar stresses at top and bottom of the optimized ply layup were validated with Autodesk’s Helius composites solver.

Wave characteristics of nonsymmetric cross-ply laminated composite beams

The free vibration characteristics of a nonsymmetric cross-ply laminated composite beam coupled in bending and longitudinal deformation is studied using a wave approach. The effects of shear deformation and rotary inertia are included in the analysis. Exact analytical expressions are derived for the natural frequencies, mode shapes, and the power flow of the propagating waves. The derived expressions are validated using the results from past literature and provide a benchmark for numerical models. The advantages of the wave approach over conventional free vibration analysis methods are highlighted. Specifically, the wave approach is used to derive a simplified expression for the mode count function of the composite beam. Additionally, the wave approach is also used to investigate the power flow and cross-conversion of the propagating wavetypes across various classical boundary conditions. The influence of the number of cross-ply layers on the natural frequencies and power flow are also investigated. The efficacy of the wave analysis is illustrated through several numerical examples.