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![Prepreg layup on a conical mandrel [23].](publication/338057881/figure/fig2/AS:865140811501568@1583277051180/Prepreg-layup-on-a-conical-mandrel-23.png)
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![Fig. 3. Prepreg layup on a conical mandrel [23].](publication/338057881/figure/fig2/AS:865140811501568@1583277051180/Prepreg-layup-on-a-conical-mandrel-23_Q320.jpg)
The current paper deals with the impact of geometrical and material parameters of the laminated conical shell on the load carrying capacity based on the finite element analysis. Various parameters were taken into account, that is, stiffness ratio, cone angle or shell height. Moreover, the mechanical behavior of conical shell having the concave and...
Contexts in source publication
Context 1
... second manufacturing method of a conical shell is the prepreg layup technique. Prepreg layup on a mandrel is fabricated by cutting a prepreg into fragments with the desired shape and laminated onto mandrel by hand lay-up - Fig. ...
Context 2
... capacity in comparison with the structure without imperfection. This effect is associated with the dynamic change of the thickness of the conical shell. The direct comparison of the influence of the particular imperfection shape on the buckling load related to the optimal solution for structures without imperfection (Ncr 0 ) is demonstrated in Fig. ...
Context 3
... the buckling load reduction effect in this case is connected with the fact that the conical shell had the greatest thickness at the top of the cone and the buckling mode is localized near the base of the structure. In the cases of imperfections localized near the base of the cone (ImB) and in the middle of the cone element (ImS) the reduction of Fig. 13. The buckling load of the structure (L = 2 × R 1 ) with different convex imperfections related to the buckling load without imperfection equal to Ncr 0 = 27.77 [Nmm]. the buckling load is associated also with the change of the buckling mode. The increase of the buckling load capacity in the ImB imperfection is determined by moving the ...
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The most influential technique in flexural strengthening of steel I-beams using carbon fiber reinforced polymers (CFRP) plates is attaching the plate to the outer face of tension flange. These strengthened beams had two most important types of failure mode, conditional on the length of the plate, end plate debonding in beams with short plates and p...
Citations
... Liu et al. (2021) studied the buckling of sphericalcylindrical composite shells under external pressure. Stawiarski et al. (2020) conducted a numerical analysis of a CFRP conical shell under axial pressure. The University of Washington has developed the Deepglider (Osse and Eriksen, 2007) for ocean exploration and conducted a two-stage design and test of carbon fiber composite hull. ...
This paper studies the strength and stability of the carbon fiber composite cylindrical hull with strengthening ribs for an autonomous underwater vehicle (AUV) based on finite element analysis (FEA) and response surface method (RSM). According to empirical formulas and test results, the value ranges of critical design parameters are preliminarily determined. In ANSYS Workbench, finite element modeling and numerical calculation of composite hulls under different design parameters are made using a tetrahedral mesh Patch Independent Algorithm (PIA). Parameter’s sensitivity analysis is finished, and the response surface optimization is carried out using the Screening and Multi-objective genetic algorithm (MOGA). In Design-Expert, the Box–Behnken method is used to design a four-factor three-level experiment, and response surface analysis and parameter optimization are carried out. The sample data is obtained from numerical calculation. Finally, a response surface quadratic model between input parameters and output parameters is established. The response surface established by the above two methods and the optimization results is compared. The accuracy of the response surface quadratic model is evaluated, and the error is within 4%. The final parameters of the hull are determined, and the strength and stability are detected. Tests and engineering applications verify the reliability of this method.
... Evidence of socalled random imperfections and their effects on system performance can be found in a broad array of fields, ranging from contact mechanics and tribology [1], to buckling of nanocomposite structures [2,3], to the design of origami-based metamaterials [4][5][6]. Examples can also be found in [7,8] for parts produced by additive manufacturing, in [9][10][11][12][13][14][15][16] for the analysis of cylindrical shells under geometrical imperfections, as well as in [2,3,[17][18][19][20][21][22][23][24][25][26][27] for composite structures under various types of loading conditions-to list a few. The existence of such imperfections is often attributed to the underlying manufacturing technology, which inevitably introduces deviations from nominal models due to, e.g., precision limitations (see [28,29] for additive manufacturing techniques), as well as to service conditions. ...
We present a stochastic modeling framework to represent and simulate spatially-dependent geometrical uncertainties on complex geometries. While the consideration of random geometrical perturbations has long been a subject of interest in computational engineering, most studies proposed so far have addressed the case of regular geometries such as cylinders and plates. Here, standard random field representations, such as Kahrunen-Loève expansions, can readily be used owing, in particular, to the relative simplicity to construct covariance operators on regular shapes. On the contrary, applying such techniques on arbitrary, non-convex domains remains difficult in general. In this work, we formulate a new representation for spatially-correlated geometrical uncertainties that allows complex domains to be efficiently handled. Building on previous contributions by the authors, the approach relies on the combination of a stochastic partial differential equation approach, introduced to capture salient features of the underlying geometry such as local curvature and singularities on the fly, and an information-theoretic model, aimed to enforce non-Gaussianity. More specifically, we propose a methodology where the interface of interest is immersed into a fictitious domain, and define algorithmic procedures to directly sample random perturbations on the manifold. A simple strategy based on statistical conditioning is also presented to update realizations and prevent self-intersections in the perturbed finite element mesh. We finally provide challenging examples to demonstrate the robustness of the framework, including the case of a gyroid structure produced by additive manufacturing and brain interfaces in patient-specific geometries. In both applications, we discuss suitable parameterization for the filtering operator and quantify the impact of the uncertainties through forward propagation.
... The experimental and theoretical studies of buckling and post-buckling behavior of composite shell structures were recently discussed and presented in the papers [38][39][40][41][42][43][44]. Such analyses were related to the structures with cut-outs and reinforcements [38], local damages [39], multilayered composite shells [40], honeycomb cylindrical shells [41], conical shells [42], and local buckling of multilayered shells and plates with cut-out under tensile loadings [43,44]. ...
... The experimental and theoretical studies of buckling and post-buckling behavior of composite shell structures were recently discussed and presented in the papers [38][39][40][41][42][43][44]. Such analyses were related to the structures with cut-outs and reinforcements [38], local damages [39], multilayered composite shells [40], honeycomb cylindrical shells [41], conical shells [42], and local buckling of multilayered shells and plates with cut-out under tensile loadings [43,44]. Concluding the above-mentioned studies, it can be said that an advantage of using fiber-reinforced composites over conventional metallic materials is that the former can be tailored to specific requirements of certain applications. ...
The present paper is devoted to the problem of the optimal design of thin-walled composite axially symmetric shells with respect to buckling resistance. The optimization problem is formulated with the following constraints: namely, all analyzed shells have identical capacity and volume of material. The optimization procedure consists of four steps. In the first step, the initial calculations are made for cylindrical shells with non-optimal orientation of layers and these results are used as the reference for optimization. Next, the optimal orientations of layers for cylindrical shapes are determined. In the third step, the optimal geometrical shape of a middle surface with a constant thickness is determined for isotropic material. Finally, for the assumed shape of the middle surface, the optimal fiber orientation angle θ of the composite shell is appointed. Such studies were carried for three cases: pure external pressure, pure twisting, and combined external pressure with twisting. In the case of shells made of isotropic material the obtained results are compared with the optimal structure of uniform stability, where the analytical Shirshov’s local stability condition is utilized. In the case of structures made of composite materials, the computations are carried out for two different materials, where the ratio of E1/E2 is equal to 17.573 and 3.415. The obtained benefit from optimization, measured as the ratio of critical load multiplier computed for reference shell and optimal structure, is significant. Finally, the optimal geometrical shapes and orientations of the layers for the assumed loadings is proposed.
... Because the morphological changes of pinecones can be applied to technology development, it was worthwhile to study the opening and closing mechanisms, as well as the structural characteristics that respond to hygroscopic action. In addition, a unique structure and system that biomimic the motion of a pinecone essentially can be applied to a hygromorphic model [26]. The results of this study can be used as scientific data for future biological and ecological characteristic analyses and applications based on the characteristic principles of a plant (pinecones) with a moisture absorption function. ...
In order to better understand the functions of plants, it is important to analyze the internal structure of plants with a complex structure, as well as to efficiently monitor the morphology of plants altered by their external environment. This anatomical study investigated structural characteristics of pinecones to provide detailed descriptions of morphological specifications of complex cone scales. We analyzed cross-sectional image data and internal movement patterns in the opening and closing motions of pinecones, which change according to the moisture content of its external environment. It is possible to propose a scientific system for the deformation of complex pinecone for the variable structures due to changes in relative humidity, as well as the application of technology. This study provided a functional principle for a multidisciplinary approach by exploring the morphological properties and anatomical structures of pinecones. Therefore, the results suggest a potential application for use in energy-efficient materials by incorporating hygroscopic principles into engineering technology and also providing basic data for biomimicry research.
This study focuses on lightweight optimum design of head pressure shell of an autonomous underwater vehicle (AUV) with reliability requirements. The grid sandwich structure is applied to the pressure shell for lightweight. An optimal mathematical model is established, which takes weight and the maximum von-Mises stress as objective and strength requirement as a constraint condition. This optimization model is solved by genetic algorithm (GA) based on back propagation (BP) neural network surrogate model, which is optimized by particle swarm optimization (PSO) for improving accuracy. Additionally, the randomness of geometry sizes, material properties and loads are considered to ensure reliability. A stress-strength interference model is established for obtaining failure probability and reliability according to statistical regularity of yield strength and the maximum von-Mises stress. The result shows that the weight of grid sandwich structure pressure shell is reduced by 38.26% compared with the solid pressure shell. The width of transverse grid has more influence on the maximum von-Mises stress than longitudinal grid. The critical load factor is 21.611 and buckling deformation will not occur under given conditions. The pressure shell with grid sandwich structure meets three sigma level with random variables, which can ensure enough reliability of AUV. The above analysis shows that application of grid sandwich structure to the pressure shell of AUV head is feasible.
