56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

Simeone, Simone; Agostinelli, Christian; Rendall, Thomas; Rampurawala, Abdul

doi:10.2514/msdm15

Cited by 3 publications

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“…In [18], the optimization of the fiber paths is driven by two distinct requirements, namely local and global stiffness tailoring that influence the buckling performance and static strength, respectively. Finally, the initial postbuckling behavior of the optimized designs is investigated using Koiter's perturbation approach, which reveals that postbuckling stability should be considered when optimizing the VAT panels.…”

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confidence: 99%

Lay-Up Optimality Conditions for Stiffness Maximization of Anisotropic Composite Plates in Postbuckling

Selyugin¹

2019

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The present paper deals with the optimization of post-buckled composite plates. The plates have a symmetric lay-up. The layer orientation angles vary in the point-wise or in the platewise ways. The von Karman theory is employed. The boundary conditions are the simple support ones or the clamped ones. The structural potential energy is treated as a measure of structural stiffness. For the plate stiffness maximization problem, the first-order necessary conditions of the local optimality are derived. The mathematical treatment of the conditions is performed. The conditions contain two terms. One of them corresponds to the mid-plane strains; another one corresponds to the plate curvatures. The optimality conditions may lead to a co-axiality of some structural tensors. An illustration of the optimality conditions is presented.-2 - INTRODUCTIONPostbuckling of thin composite plates attracts the attention of numerous researchers, working in various modern application areas. Among these applications, there are the aerospace, the automotive, the marine, and the civil ones. According to design practice in composite structures, the account of the load-carrying capability "above buckling" gives an opportunity of extra weight saving, as compared to existing traditional design.Composite plates are a part of a considerable number of structures in the above applications. The loading applied to the plates is a combination of compression and shear. The compression dominates for the structures similar to the upper panels of an airplane wing structure. As the examples of known structures designed for pure shear, one may indicate airplane wing ribs and spars, as well as some fuselage panels. As a rule, the shear-loaded plates have the so-called angle-ply symmetric lay-up. For example, buckling is not allowed in airplane structures in the case of loading up to the so-called limit loads (LL) and may be allowed for the loading level between the limit loads and the so-called ultimate loads (UL).The latter loads are 1.5 times higher than the limit loads.When optimizing the composite plate, an engineer, in fact, does his best to save the structural weight, the material cost, and the production time. Due to that, the optimization problems for the composite plates attract considerable attention at the design phase. The layup optimization problem is one of them requiring a solution at the beginning of the design process. Since the last decade of the previous century, numerous papers dealt with the lay-up optimization of composite plates. The non-exhaustive list [1]-[22] contains the important publications devoted to the postbuckling analysis and optimization. The foundations of the postbuckling theory are described in [23].

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confidence: 99%

Lay-Up Optimality Conditions for Stiffness Maximization of Anisotropic Composite Plates in Postbuckling

Selyugin¹

2019

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“…The initial imperfection of the post-buckling analysis is equal to 1.E-05 times the transverse displacement of the first buckling mode. The similar approach was successfully used in [18]. In other papers like [17], the multiplier was 1% of the plate thickness.…”

Section: Preliminary Considerationmentioning

confidence: 99%

“…After some trials, we chose the level of loading above buckling for every configuration of the paper basing on the necessity of having maximal compression strain level not higher than 5000 micro strains (see [18]). The criterion is of frequent use in aerospace applications [18]. It is clear that the criterion is only an approximation of the real failure conditions.…”

Section: Preliminary Considerationmentioning

confidence: 99%

“…The studies were initiated in the last decade of the previous century in Virginia Tech, Delft University, Bristol University, and other locations. For references, one may use the most recent papers like [16][17][18]. In such papers, the advantages of VAT composites for post-buckling load-carrying capacity are explored numerically and compared to the so-called "quasi-isotropic" or "straight fiber" solutions.…”

Section: Introductionmentioning

confidence: 99%

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Composite Plates and Their Lay-Up Solutions Leading to High Buckling and Post-Buckling Resistance

Selyugin¹

2019

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At the beginning of the present paper, the post-buckled composite plates are examined. The plates have a symmetric lay-up. The layer orientation angles vary in a point-wise way or in a plate-wise way. The von Karman theory describes a plate behavior. For a plate stiffness maximization problem the first-order optimality conditions are derived. In the conditions, the essential roles play the mid-plane principal strains and the principal curvatures. The optimality conditions may lead to a co-axiality of some structural tensors. Analytical examples illustrate the solutions of such types. Further, several numerical examples are presented. In the examples, the plates are loaded by shear and have the high buckling-resisting ability also. A significant conclusion of the paper is that in the properly designed lay-up the outermost layers and the innermost layers play different roles. The former ones withstand mainly buckling, and the latter ones withstand mainly post-buckling. The innermost layers have the orientation angle rather close to 0°. The weight reduction opportunities are demonstrated.

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Integrated fiber optic structural health sensors for inflatable space habitats

2017

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56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

Cited by 3 publications

References 0 publications

Lay-Up Optimality Conditions for Stiffness Maximization of Anisotropic Composite Plates in Postbuckling

Lay-Up Optimality Conditions for Stiffness Maximization of Anisotropic Composite Plates in Postbuckling

Composite Plates and Their Lay-Up Solutions Leading to High Buckling and Post-Buckling Resistance

Integrated fiber optic structural health sensors for inflatable space habitats

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