Generally, a grid layer is used as an orthotropic layer to reinforce plates and shells or as an independent structural element. The proposed laminated grid plate is composed of different grid layers with different orientations. Consequently, the grid layers with different fibers, patterns and orientations can be used, resulting in laminates with enhanced stiffness and coupling effects. In the present study, to investigate the efficiency of the laminated grids, the vibration and buckling responses of a conventional and laminated grid plates are compared. The first-order shear deformation plate theory along with Ritz method is used to obtain the buckling load and natural frequencies of the plates. The effectiveness of increasing the number of layers on mechanical responses of the laminated grids is also studied. The analytical results of vibration frequencies are compared and validated by finite element method and experimental analysis of two manufactured grid plates. The results indicate that thoughtful selection of stacking sequences of the laminated grids considerably enhances the response of the laminated grids in comparison with conventional grids.
The present work describes an optimization process based on the ε-constraint method to find an optimum design to maximize the critical buckling load and minimize the structural weight of an angle grid plate. A comprehensive geometrical model is considered including all geometrical design variables of the grid. In order to achieve a precise and effective approximation of the buckling load, an artificial neural network (ANN) is employed. Training data for ANN is obtained by the Mindlin plate theory as well as the Ritz method. The ANN is combined with genetic algorithms (GA) to find optimized design variables for the angle grid structure. The results provide a wide range of geometrical data for designers to choose the maximum buckling load at the minimum structural weight.
This study presents the multi‐objective optimization of weight and cost concerning the vibration behavior of a sandwich structure. In this regard, the maximization of frequency against the minimization of the structure's weight or cost is considered the objective functions in the optimization algorithm. For this purpose, a sandwich structure with two composite skins and an orthotropic grid core is designed. The design variables including the core geometrical variables, and the type of the applied composite materials for each group of stiffeners of the core. The first‐order shear deformation theory and the Ritz method have been used to obtain the natural frequencies of the plates. Eventually, optimization has been performed using the genetic algorithm.
This paper intends to present the application of laminated grid structures as a new class of stiffeners for reinforcing body and chassis of transportation vehicles. A laminated grid plate is constituted from several grid plies with different orientations. Therefore, the grid layers with various fibers, patterns, and orientations can be used, resulting in laminates with enhanced stiffness and coupling effects. In this study, a hypothetical trunk floor is assumed as a sandwich panel with two skins and a composite laminated grid core, which is clamped along all edges. Three different grid structures are considered as the core to strengthen the trunk floor subjected to arbitrary lateral loads. Moreover, the first natural frequency of the plates are achieved. The Ritz method is employed to obtain the maximum deflection and free vibration frequencies of the trunk's floor panel. The results indicate that employing the laminated grids considerably enhances the response of the panel in comparison with conventional grids.
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