A general global-local modelling framework for the deterministic optimisation of composite structures

Abstract

This work deals with the multi-scale optimisation of composite structures by adopting a general global-local (GL) modelling strategy to assess the structure responses at different scales. The GL modelling approach is integrated into the multi-scale two-level optimisation strategy (MS2LOS) for composite structures. The resulting design strategy is, thus, called GL-MS2LOS and aims at proposing a very general formulation of the design problem, without introducing simplifying hypotheses on the laminate stack and by considering, as design variables, the full set of geometric and mechanical parameters defining the behaviour of the composite structure at each pertinent scale. By employing a GL modelling approach, most of the limitations of well-established design strategies, based on analytical or semi-empirical models, are overcome. The GL-MS2LOS makes use of the polar formalism to describe the anisotropy of the composite at the macroscopic scale (where it is modelled as an equivalent homogeneous anisotropic plate). In this work, deterministic algorithms are exploited during the solution search phase. The challenge, when dealing with such a design problem, is to develop a suitable formulation and dedicated operators, to link global and local models physical responses and their gradients. Closed-form expressions of structural responses gradients are rigorously derived by taking into account for the coupling effects when passing from global to local models. The effectiveness of the GL-MS2LOS is proven on a meaningful benchmark: the least-weight design of a cantilever wing subject to different design requirements. Constraints include maximum allowable displacements, maximum allowable strains, blending, manufacturability requirements and buckling factor.

Structural analysis and improvement for a new form traveler in long-span cantilever-casting arch bridge

“…Structural optimization includes performance improvement and weight reduction, which is particularly important in aircraft structure. [23][24][25][26][27][28] This paper, based on the new form traveler adopted in the cantilever construction of Ye-Lang Lake Bridge with a main span of 210 m, aims to improve its structural details and verifies its working performance by carrying out the load test, thus provides useful references for the cantilever casting of similar long-span arch bridges in the future.…”

Large-scale smooth plastic topology optimization using domain decomposition

“…The topology design of continuum structures of practical significance often requires complex finite element models that lead to large size optimization problems exceeding the available computational and storage capacities. Typical examples of such large problems include the design of three-dimensional (3D) structures [1,2], problems involving multiple geometric scales, and problems dealing with the simultaneous design of material and structure [3,4]. A variety of strategies known under various designations such as global-local [4], multilevel [5], and decomposition [6][7][8] have been developed for handling large-scale mathematical problems.…”

“…These strategies generally consist of splitting the posed problem into a controlled series of smaller problems that can be solved sequentially or in parallel. Many decomposition techniques have been proposed for solving large problems in the topology optimization of elastic structures [3,4,9,10]. However, decomposition schemes for plastic topology design of continua are yet to be developed.…”

“…In addition, they incorporate filtering techniques [33] and geometric constraints [1,34] to eliminate the checkerboard and mesh dependence phenomena associated with the ill-posedness of the problem. Recently, research in topology optimizations of elastic media is witnessing increased interest in large-scale and multilevel methods [4] as problem complexity and size continue to grow.…”

“…The decomposition was carried out with respect to the macroscale finite elements, which play the role of subdomains, and the associated local optimization problems were solved in parallel. In [4], a general framework is proposed for the simultaneous design of the structure and the composite material in a multi-scale optimization strategy that accounts for the fully detailed description and behavior of the composite material at the relevant scale. While this strategy was illustrated in a sizing design framework, the concept can be extended to topology optimization.…”