Ant Colony Optimization for dispersed laminated composite panels under biaxial loading

The current study aims to show the benefits of dispersed laminates (laminates in which the orientation angles are not limited to the conventional, 0°, ±45° and 90°, orientations) over conventional ones, in terms of stiffness, buckling resistance and strength, in structural applications. The Ant Colony Optimization algorithm is used with strength constraints to find the best candidate to achieve this goal. A study is conducted to select the most suitable failure criterion among three common ones.The methodology is used for two loading cases: biaxial compression and biaxial tension. In the case of biaxial compression, the problem is formulated to maximize the critical buckling load whereas with the biaxial tension, the formulation is to minimize the failure index. For both loading cases, the methodology succeeds in improving the response of dispersed laminates with respect to the conventional ones. These results support the movement of the composite industry toward using dispersed laminates.     

Numerical investigation to prevent crack jumping in Double Cantilever Beam tests of multidirectional composite laminates

During the experimental characterization of the mode I interlaminar fracture toughness of multidirectional composite laminates, the crack tends to migrate from the propagation plane (crack jumping) or to grow asymmetrically, invalidating the tests.The aim of this study is to check the feasibility of defining the stacking sequence of Double Cantilever Beam (DCB) specimens so that these undesired effects do not occur, leading to meaningful onset and propagation data from the tests. Accordingly, a finite element model using cohesive elements for interlaminar delamination and an intralaminar ply failure criterion are exploited here to thoroughly investigate the effect of specimen stiffness and thermal residual stresses on crack jumping and asymmetric crack growth occurring in multidirectional DCB specimens.The results show that the higher the arm bending stiffness, the lower the tendency to crack jumping and the better the crack front symmetry. This analysis raises the prospect of defining a test campaign leading to meaningful fracture toughness results (onset and propagation data) in multidirectional laminates.     

Microwave shielding performance of TiO2/Co/GF containing high structure carbon fiber alternate laminate composite

Journal of Materials Science: Materials in Electronics - Recently, the design of low cost, lightweight, and flexible electromagnetic interference (EMI) shielding fabrics mitigation is a great...     

Instability and post-instability examination due to the buckling of rotating nanocomposite beams in thermal ambient

International Journal of Mechanics and Materials in Design - This work has been conducted to investigate the instability and post-instability response of rotating nanocomposite beams because of...     

Analytical solution for static and dynamic analysis of FGP cylinders integrated with FG-GPLs patches exposed to longitudinal magnetic field

Motivated by progressive sandwich structures’ usage due to their high strength to weight ratio in different industries, the current paper aimed at evaluating static and dynamic behaviors of three-layered cylinders including FG porous core and two graphene nanoplatelet (GPLs)-reinforced composite as face sheets. The whole sandwich cylinder rests on Pasternak substrate and it is also exposed to a longitudinal magnetic field. Epoxy has used as matrix and GPLs as the reinforcing phases for top and bottom face sheets and based on the rule of mixture and Halpin–Tsai micromechanical models, effective values for mechanical properties of skins are gained. Besides, regarding the integrity of current research, all layers of model are assumed to be FG, which means for the porous core the placement of the pores is considered and for the faces, the GPLs dispersion patterns are regarded. Among different shell theories, sinusoidal shear deformation shells theory (SSDST) is utilized to define displacement components along with the major axes. Hamilton’s principle is hired to attain governing equations for vibrational and buckling analyses. In the end, the effects of different variables’ alternation as the model’s geometry, foundation moduli, mode number, and mid-radius on vibrational and buckling behaviors are interpreted in type of different plots and tables. Pores’ placement and GPLs dispersion patterns play important roles in static and dynamic responses of the under-consideration cylinder. The outcomes of this study may help to create more efficient engineering structures such as pressure vessels.

     

Characterization of crack propagation in mode I delamination of multidirectional CFRP laminates

During the experimental characterization of the mode I interlaminar fracture toughness of multidirectional composite laminates, the crack tends to migrate from the propagation plane (crack jumping) invalidating the tests. In an earlier numerical study [9], we reported that this problem could be eliminated by choosing the appropriate bending stiffness of the beam arms.