A review of topology optimization for additive manufacturing: Status and challenges

A review on optimization of composite structures Part I: Laminated composites

An integrated framework of exact modeling, isogeometric analysis and optimization for variable-stiffness composite panels

Buckling of quasi-perfect cylindrical shell under axial compression: A combined experimental and numerical investigation

Variations of manufacturing process parameters, environment aspects, and imperfections may significantly affect the quality and performance of stiffened shells. The reliability-based design optimization (RBDO) of stiffened shells, considering all these uncertainty factors simultaneously, is extremely time-consuming, even if the surrogate-based technology is used. Therefore, a hybrid bi-stage framework for RBDO of stiffened shells is presented to release the computational burden, where two main sources of uncertainties are considered: variations of material properties and geometric dimensions are described as random variables, while various forms of imperfections of stiffened shells are covered by the single perturbation load approach. The basic idea of the proposed method is to combine the efficiency of smeared stiffener method with the accuracy of finite element method, and then narrow the design window efficiently with little accuracy sacrifice. The adaptive chaos control method is used to ensure the ro...

Hybrid Framework for Reliability-Based Design Optimization of Imperfect Stiffened Shells

An efficient optimization framework of cylindrical stiffened shells with reinforced cutouts by curvilinear stiffeners is proposed in this study. First, an adaptive method to determine the near field around the cutout and far field away from the cutout is presented. Then, a novel hybrid model is established to reduce the computational efforts of postbuckling analysis; the numerical implementation asymptotic homogenization method is used to smear out the stiffeners in the far field, and curvilinear stiffeners are adopted to improve the loading path and thus local stiffness of the near field, which can provide a type of flexible stiffener configurations for cutout reinforcement. After that, the optimization of curvilinear stiffeners is performed by a novel bilevel strategy based on the hybrid model. In the first level, a stiffener distribution function is used to reduce the number of active variables, and then stiffener layout, stiffener number, and section profile are optimized simultaneously. In the second...

Efficient Optimization of Cylindrical Stiffened Shells with Reinforced Cutouts by Curvilinear Stiffeners

Buckling optimization of variable-stiffness composite panels based on flow field function

Buckling is usually initiated from a local region near the cutout for cylindrical stiffened shells under axial compression, and then the evolution of buckling waves is governed by the combined effects of local and global stiffness, which limit the load-carrying capacity. Therefore, a simultaneous buckling pattern is crucial for improving the structural efficiency. In this study, a multi-step optimization strategy for the integrated design of near and far fields away from cutouts is proposed, and the convergence criterion of buckling optimization is improved as a deformation-based index. The numerical implementation of the asymptotic homogenization method is utilized to construct an efficient finite element model for post-buckling analysis. A 5 m diameter stiffened shell in a launch vehicle demonstrates that the proposed framework can provide a simultaneous buckling design with high structural efficiency in an efficient manner. Both the buckling deformations and stress of the optimum design are mor...

Simultaneous Buckling Design of Stiffened Shells with Multiple Cutouts

The invention relates to composite material structure design in aerospace structures, and provides an efficient optimization method for a variable stiffness composite material plate shell structure. The method includes the steps: performing curve fiber path accurate modeling and buckling analysis on the variable stiffness composite material plate shell structure based on an isogeometric method; building an isogeometric buckling design model of the structure; deriving total analytical sensitivity of buckling response of the variable stiffness composite material plate shell structure; efficiently optimizing fiber paths of the variable stiffness composite material plate shell structure by a gradient-based method to obtain an optimal structure meeting process manufacturing constraints. According to the structure, the carrying efficiency of the variable stiffness composite material plate shell structure can be remarkably improved, and the development period of products is greatly shortened.

Fei Niu

Papers

An integrated framework of exact modeling, isogeometric analysis and optimization for variable-stiffness composite panels

Efficient Optimization of Cylindrical Stiffened Shells with Reinforced Cutouts by Curvilinear Stiffeners

Buckling optimization of variable-stiffness composite panels based on flow field function

Simultaneous Buckling Design of Stiffened Shells with Multiple Cutouts

Efficient optimization method for variable stiffness composite material plate shell structure