Light Weight Composite and Sandwich Structural Analysis Using Improved Higher Order Theory with Consideration of LayerWise Technique

Abstract

Abstract Nowadays, lightweight sandwich and composite structures are widely used in the aeronautical, aerospace, and marine industries. To gain a superior level of safety, a higher payload, and good fatigue resistance properties, light weightiness, and optimum strength should play a vital role. Likewise, sandwich and composite structures are complicated in terms of the analysis and design aspect, because of the existence of some unforeseen failure modes, such as delamination, is considered. To overcome the aforementioned challenges, continuous research has been conducted with the advantage of tailoring lamina orientations. The analysis of laminated structure would be the primary focus for several decades for space and marine industries. As a result, a huge volume of research printouts are available that bears a variety of analytical modeling and numerical methods. Therefore, in this study, based on the gaps of previous works, a refined sandwich, and composite laminate analysis has been conducted; incorporating inter-laminar strain energy continuity into the interfaces, to estimate the mechanical properties of stiff lightweight structures. Section two of the study, improved higher order principle with layer-by-layer refined theory should be used to investigate flawlessly wedged sandwich and composite beams, with general laminate configurations. The analysis incorporates continuity assumptions of interfacial strain energy, in-plane and flexural displacements between the plies. Additionally, the inter-laminar shear stresses are constrained, using the Lagrange multiplier technique, by introducing new unknown variables. The unknown variables expressed using inter-laminar strain energy; assuming the strain energy is uniform throughout the overall thickness of the beam. To govern the newly introduced and other unknown variables, the total potential energy (TPE) is minimized using variational calculus. The numerical analysis is done using the MuPAD code and the result is contrasted, against existing and reliable, published papers. In the third part, a perfectly stacked sandwich plate, with the usual type lamination configurations, has been analyzed using enhanced higher-order refined theory. The examination has used kinematical analysis to formulate the flexural and in-plane displacements. Furthermore, to model the governing equilibrium equation, the inter-laminar shear stresses and the displacement was assumed to be uniformly continuous throughout perfectly bonded plies. Moreover, the shear on the transverse direction of the upper and lower face the ply was considered as zero. The transverse stress and the displacement were constrained with an unknown variable Lagrange multiplier to illustrate the inter-laminar strain energy continuity. The unknown variables are obtained by using closed-form analytical solutions. The numerical analysis was carried out and the investigation results were verified using existing reliable results. Also, to enhance the accuracy more in-detail parametric tests were conducted using the shear and transverse direction tensile modulus. The last part of the study suggests improved refined theory to the investigation of perfectly bonded composite laminates with common lamination patterns. The investigation assumed inter-laminar strain energy continuity throughout the thickness of each ply. Furthermore, the transverse shear stress is continuous and also constrained, using the Lagrange multiplier technique, by introducing new unknown variables. To determine the newly introduced flexural and in-plane unknown variables, the total potential energy (TPE) is minimized using the variational approach. The numerical results are obtained and compared with the existing research results that are reliable.