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Structural and Multidisciplinary Optimization
Journal Prestige (SJR): 1.458
Citation Impact (citeScore): 3
Number of Followers: 12  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1615-1488 - ISSN (Online) 1615-147X
Published by Springer-Verlag Homepage  [2469 journals]
  • Vibration acceleration-integrated parameterized aerodynamic shape
           optimization of super high-rise buildings with spiral configurations

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      Abstract: Abstract A novel multi-objective vibration acceleration-integrated aerodynamic shape optimization strategy is put forward for super high-rise buildings with spiral configurations during their preliminary design stage. The strategy specifically accounts for the dual concern of economy and wind-induced vibration comfortability, in terms of the profitability coefficient and the peak wind-induced vibration acceleration. The optimization problem is formulated fully based on the design feature of super high-rise buildings. The Grasshopper®-based parametrized computational fluid dynamics modeling is applied to more efficiently obtain the shape coefficients of building. The previously proposed modified generalized flexure-shear model is utilized to quickly achieve an acceptably conservative estimate on the response of buildings with mass and stiffness non-uniform distributions, with the artificially generated wind pressure time histories. To save the computing cost of the non-dominated sorting genetic algorithm (NSGA-II), the Kriging model using the optimal Latin hypercube sampling, the GPU-based parallel sorting and the conjugate gradient algorithm have been incorporated. The efficiency, stability and accuracy of the proposed shape optimization strategy are verified on a 100-story super high-rise building with a spiral configuration. From the case study, it is recommended to modify the twist angle, height-to-width ratio and tapering ratio in sequence if the peak acceleration is controlled on the premise that the profitability is maintained as much as possible. The height-to-width ratio and tapering ratio are observed to act as the two active constraints for preventing the extension of the Pareto front.
      PubDate: 2022-09-23
       
  • Kriging-based analytical technique for global sensitivity analysis of
           systems with multivariate output

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      Abstract: Abstract Global sensitivity analysis is of great significance for risk assessment of structural systems. In order to efficiently perform sensitivity analysis for systems with multivariate output, this paper adopts Kriging-based analytical (KBA) technique to estimate multivariate sensitivity indices (MSI). Two MSI are studied in this paper, namely, MSI based on principal component analysis (MSI-PCA) and MSI based on covariance decomposition (MSI-CD). For MSI-PCA, Kriging models of inputs and each retained output principal component (PC) are firstly established, and then KBA technique is used to derive the sensitivities associated with each retained PC and the generalized MSI-PCA. For MSI-CD, Kriging model is constructed to map input variables and each time output variable, based on which subset variances and the corresponding MSI-CD are derived by KBA technique. In addition, to avoid constructing Kriging model at each time instant when calculating MSI-CD, a new double-loop Kriging (D-Kriging) method is developed to further improve the efficiency. The accuracy and efficiency of KBA and D-Kriging methods for MSI estimation are tested and discussed by four examples in Sect. 4.
      PubDate: 2022-09-22
       
  • Size optimization of mid-frequency vibro-acoustic systems in the framework
           of modal energy analysis

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      Abstract: Abstract Modal energy analysis (MODENA) is an energy-based method to compute the pure tone mid-frequency response of a vibro-acoustic system. This method considers frequency-dependent modal energies, input power, dissipated power and transmitted power between the modes of coupled subsystems. The quantities are determined by the basic modal information of the uncoupled subsystems, which also has a close relationship with the structural sizes. The present work addresses developing a size optimization procedure within the framework of MODENA to reduce the mid-frequency acoustic response of vibro-acoustic systems. Via a gradient-based optimization algorithm, the sensitivity of the acoustic energy at pure tone with respect to the structural thickness is deduced by employing a complex variable method. By optimizing the thicknesses on different areas of the structural subsystem given the constraint on total mass, the global energy of the acoustic subsystem is reduced significantly. Furthermore, in an effort to examine the capability of the proposed optimization procedure in dealing with acoustic and aerodynamic excitations encountered in engineering problems, the noise reduction of vibro-acoustic systems under turbulent boundary layer (TBL) pressure fluctuations is investigated. The optimization procedure is demonstrated on a plate/cavity system excited by a point drive and by TBL flow and two kinds of vehicles subject to TBL excitation.
      PubDate: 2022-09-22
       
  • An aeroelastic optimisation framework for manufacturable variable
           stiffness composite wings including critical gust loads

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      Abstract: Abstract This work presents a new aeroelastic optimisation framework for the preliminary design of variable stiffness composite wing structures. The framework is constructed by sequentially and iteratively solving two sub-problems: aeroelastic tailoring and lay-up retrieval, using gradient-based algorithms with full-analytical sensitivities provided. During aeroelastic tailoring, the wing mass is minimised by optimising the lamination parameters and thickness of wing laminates together with wing jig twist distribution. The load cases cover not only static loads, but also the critical gust loads that are identified across the entire flight envelop at every iteration of optimisation. Further, a cruise shape constraint is included in addition to other aerostructural constraints, so that the optimal aircraft performance can be ensured. During lay-up retrieval, the manufacturable stacking sequence is retrieved according to the optimal lamination parameters with the consideration of minimal steering radius constraint. Moreover, to fix the possible constraint violations caused by lay-up retrieval, a correction strategy is incorporated to tighten the violated constraints for repeating aeroelastic tailoring. Finally, several case studies on the design of NASA common research model wing are carried out and investigated. The results indicate that the critical gust loads and cruise shape constraint have a large influence on the design of tow-steered composite wing structures, which therefore demonstrate the usefulness and benefits of the proposed optimisation framework.
      PubDate: 2022-09-22
       
  • Decoupled reliability-based design optimization with a double-step
           modified adaptive chaos control approach

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      Abstract: Abstract Reliability analysis using first-order reliability methods (FORM) has been widely used in reliability-based design optimization (RBDO) due to their simplicity and efficiency. The performance of the RBDO is highly dependent on how it deals with the loops of deterministic optimization and reliability analysis as well as the process of reliability assessment. In this paper, sequential optimization and reliability analysis (SORA) is employed to reduce the computational cost of RBDO. Moreover, a double-step modified adaptive chaos control method (DS-MACC) based on an improved adaptive chaos control approach is developed to speed up the reliability analysis loop. In the method presented here, two sets of novel criteria are introduced within two steps to distinguish the condition of the iterative process, compute and modify the step size. The efficiency and robustness of the proposed method is shown with eight inverse reliability problems and five RBDO examples and is compared with some methods developed recently. The results illustrate that the proposed method is more efficient with a competitive convergence rate.
      PubDate: 2022-09-21
       
  • Moving-zone renewal strategy combining adaptive Kriging and truncated
           importance sampling for rare event analysis

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      Abstract: Abstract In practice, a vital challenge problem is how to accurately evaluate the failure probability of rare events with a minimum of samples. Although adaptive Kriging combined with truncated importance sampling (AK-TIS) provides a viable method to address this problem, unsatisfied samples are often added in Kriging modeling and thereby result in an unacceptable computing burden. To efficiently acquire best-desired samples and reduce the calls of real limit state function (LSF), a moving-zone renewal (MZR) strategy-based AK-TIS (MZR-AK-TIS) approach is proposed. By dividing the whole large candidate sampling pool into several small sub-candidate sampling pools, the MZR strategy can ceaselessly find desired samples and update the Kriging model as the moving of the sub-sampling pool. MZR-AK-TIS not only inherits the advantages of AK-TIS but also reduces its computing time in two aspects. One is the size reduction of the candidate sampling pool in each sub-zone, and the other is the reduction of the call number of real LSF since the samples outside the sub-sampling pool do not need to participate in Kriging updating. The proposed method is verified by several numerical cases and applied to the aeroengine variable stator vane mechanism. The analysis results demonstrate that MZR-AK-TIS holds the potential to reduce the computing cost while ensuring accuracy in rare event analysis.
      PubDate: 2022-09-21
       
  • Model order reduction for film-cooled applications under probabilistic
           conditions: sparse reconstruction of POD in combination with Kriging

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      Abstract: Abstract In this paper, to reduce the computational cost of Proper Orthogonal Decomposition (POD) method in film-cooling problems, a new method based on the combination of POD method with Sparse Polynomial Chaos Expansion (PCE) and Kriging approaches is developed. In the present method, firstly, by combining compressed sensing and POD methods, the optimal basis functions are obtained via low-fidelity calculations. These basis functions are subsequently used in the trend part of the Kriging surrogate model. Then, the trend coefficients and the stochastic Gaussian part are estimated through a limited number of high-fidelity calculations. The performance of the proposed method is investigated on two challenging test cases: 1) film-cooling jet in cross-flow and 2) leading edge film cooling of a gas turbine blade with 7 and 10 uncertain variables, respectively. For the first test case, the new method reduces the computational cost by \(91\%\) and \(53.9\%\) with respect to the full PCE and POD methods. For the second test case, the computational cost reductions are \(81\%\) and \(37.9\%\) in comparison to the full PCE and POD methods, respectively. In general, the proposed method is better in terms of accuracy in comparison to combined POD and compressed sensing, especially in the cases with the lower number of low-fidelity samples.
      PubDate: 2022-09-21
       
  • Density-based topology optimization of thin plate structure with geometric
           nonlinearity using a three-dimensional corotational triangle element
           formulation

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      Abstract: Abstract Topology optimization for three-dimensional (3D) thin plate structure is an attractive methodology for versatile industrial and biomedical applications. For this perspective, the topology optimization requires an appropriate treatment of the 3D geometric nonlinearity of thin structures that avoids numerical instabilities, which is a well-known challenge in topology optimization. This paper develops a density-based topology optimization for thin plates and considers geometric nonlinearity using a 3D corotational triangle element formulation. The corotational formulation is an approach for expressing a finite deformation by dividing small strains and finite rotations into local element coordinates. Thus, the mechanical behavior in local coordinates can be assumed to be linearly elastic behavior that follows the small strain theorem. This technique is expected to be effective and stable for topology optimization with geometric nonlinearity. Complementary work minimization with volume constraints was applied for density-based topology optimization of the plate structure by a solid isotropic material with penalization method. Numerical examples of two benchmarks demonstrated consistencies with existing related works. We conducted topology optimization of an ankle-foot orthosis (AFO) as a biomedical application and showed the capabilities of the proposed methodology and the minimum increases of the complementary work with an optimum design with a volume reduction ratio. These achievements highlight the capabilities of the developed topology optimization as an efficient framework and feasibilities for a new orthosis design.
      PubDate: 2022-09-21
       
  • A new fluid-based strategy for the connection of non-matching lattice
           materials

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      Abstract: Abstract We present a new algorithm for the design of the connection region between different lattice materials. We solve a Stokes-type topology optimization problem on a narrow morphing region to smoothly connect two different unit cells. The proposed procedure turns out to be effective and provides a local re-design of the materials, leading to a very mild modification of the mechanical behavior characterizing the original lattices. The robustness of the algorithm is assessed in terms of sensitivity of the final layout to different parameters. Both the cases of Cartesian and non-Cartesian morphing regions are successfully investigated.
      PubDate: 2022-09-21
       
  • A maximum-rectifier-function approach to stress-constrained topology
           optimization

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      Abstract: Abstract This paper introduces a novel method for stress-constrained topology optimization in which the stress constraint is a differentiable approximation of the maximum element stress violation in the structure. The element stress violation is given by a differentiable rectifier function. A key feature of the proposed method is its ability to render designs that satisfy the stress limit without renormalization of the constraint, as in some existing aggregation approaches. Numerical experiments demonstrate that the proposed technique exhibits better convergence and is less sensitive to the aggregation parameter than aggregation methods that employ renormalization. The effectiveness of the proposed method is demonstrated by several examples.
      PubDate: 2022-09-21
       
  • A space-preserving data structure for isogeometric topology optimization
           in B-splines space

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      Abstract: Abstract In this work, we put forward a space-preserving data structure for isogeometric topology optimization in B-splines space, exploiting the Bėzier extraction operator of B-splines. According to the space-preserving nature of Bernstein basis function space within an individual isogeometric analysis element, we derive the standard elemental stiffness matrix for all Bėzier elements. With the aid of Bėzier extraction matrix obtained from the knot insertion algorithm, all the elemental stiffness matrices of B-spline elements can be equivalently expressed by the aforementioned standard Bėzier stiffness matrix. The data processing arrays are put forward for B-spline and Bėzier isogeometric analysis meshes, which constitute the space-preserving data structure for isogeometric topology optimization. Three numerical examples are used to validate the effectiveness of the proposed space-preserving data structures for isogeometric topology optimization, where the maximum memory burden is decreased by four orders of magnitude, and the maximum computational efficiency is improved by two orders of magnitude, involved in storing and computing the essential data for the stiffness matrices of all B-spline elements, in comparison with the conventional space-varying data structure. Therefore, the proposed space-preserving data structure is a promising way of implementing isogeometric topology optimization method.
      PubDate: 2022-09-19
       
  • Correction: On projection methods, convergence and robust formulations in
           topology optimization

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      PubDate: 2022-09-17
       
  • Axial crashworthiness and multi-objective optimization of single-hat beams
           with sinusoidal cross-sections

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      Abstract: Abstract Restricted by the molding process and the layout of tires and powertrains, the front rails of vehicles often adopt single-hat or single-hat-like structures. They are prone to bend in the axial collision, which reduces the crashworthiness of automobiles significantly. In this work, the axial impact performance of single-hat beams is studied to improve their crashworthiness. The experiments are performed to verify the accuracy of simulation model. The cross-sectional shapes of the single-hat beams are designed based on the sine wave. Seven different sinusoidal cross-sections are proposed, and their crashworthiness is investigated. It is found that the impact performance of the single-hat beam tends to increase with the increase of amplitude and number of sine waves. At high amplitudes of sine wave, the single-hat structures with cross-sectional shape 7 (CS7), cross-sectional shape 3 (CS3), and cross-sectional shape 6 (CS6) tend to have the best performance. Three models with typical sinusoidal cross-sections are selected for multi-objective optimization design, and multiple sets of Pareto optimal solutions are obtained and analyzed. These results are very significant for the impact performance design of single-hat structures and the crashworthiness design of automobiles.
      PubDate: 2022-09-17
       
  • MILP-based discrete sizing and topology optimization of truss structures:
           new formulation and benchmarking

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      Abstract: Abstract Discrete sizing and topology optimization of truss structures subject to stress and displacement constraints has been formulated as a Mixed-Integer Linear Programming (MILP) problem. The computation time to solve a MILP problem to global optimality via a branch-and-cut solver highly depends on the problem size, the choice of design variables, and the quality of optimization constraint formulations. This paper presents a new formulation for discrete sizing and topology optimization of truss structures, which is benchmarked against two well-known existing formulations. Benchmarking is carried out through case studies to evaluate the influence of the number of structural members, candidate cross sections, load cases, and design constraints (e.g., stress and displacement limits) on computational performance. Results show that one of the existing formulations performs significantly worse than all other formulations. In most cases, the new formulation proposed in this work performs best to obtain near-optimal solutions and verify global optimality in the shortest computation time.
      PubDate: 2022-09-17
       
  • The anti-fatigue lightweight design of heavy tractor frame based on a
           modified decision method

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      Abstract: Abstract This paper proposes a modified preference selection index (MPSI) to improve the efficiency and reliability of the multi-criteria decision-making process. MPSI absorbs the high efficiency of the preference selection index (PSI) and enhances the anti-interference ability of some performance indicators. Moreover, a lightweight optimization method based on multi-performance is proposed, combining Hammersley, the radial basis function neural networks-response surface method (RBFNN-RSM), and the non-dominated sorting genetic algorithm-II (NSGA-II) and MPSI. First, the finite element model and rigid-flexible coupled virtual prototype model are established and verified and the fatigue life of the original frame is calculated. Second, the size and shape of the frame were taken as variables, and the mass, root mean square stress, and life were taken as objectives. The experimental scheme is determined, and the RBFNN-RSM hybrid surrogate model and NSGA-II are used to find the optimal solution set. Finally, the optimal solution is determined using the PSI, principal component analysis-gray relational analysis (P-GRA), and MPSI. The results show that MPSI has higher reliability than PSI; the MPSI has higher efficiency than P-GRA.
      PubDate: 2022-09-17
       
  • Optimal design of functionally graded lattice structures using Hencky
           bar-grid model and topology optimization

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      Abstract: Abstract Presented herein is a novel design framework for obtaining the optimal design of functionally graded lattice (FGL) structures that involve using a physical discrete structural model called the Hencky bar-grid model (HBM) and topology optimization (TO). The continuous FGL structure is discretized by HBM comprising rigid bars, frictionless hinges, frictionless pulleys, elastic primary and secondary axial springs, and torsional springs. A penalty function is introduced to each of the HBM spring’s stiffnesses to model non-uniform material properties. The gradient-based TO method is applied to find the stiffest structure via minimizing the compliance or elastic strain energy by adjusting the HBM spring stiffnesses subjected to prescribed design constraints. The optimal design of FGL structures is constructed based on the optimal spring stiffnesses of the HBM. The proposed design framework is simple to implement and for obtaining optimal FGL structures as it involves a relatively small number of design variables such as the spring stiffnesses of each grid cell. As illustration of the HBM-TO method, some optimization problems of FGL structures are considered and their optimal solutions obtained. The solutions are shown to converge after a small number of iterations. A Python code is given in the Appendix for interested readers who wish to reproduce the results.
      PubDate: 2022-09-16
       
  • Effective band-selection algorithm for rolling element bearing diagnosis
           using AE sensor data under noisy conditions

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      Abstract: Abstract When diagnosing a rolling element bearing (REB), it is important to select the frequency band that has the most defect information. Many band-selection methods have been developed in recent years. Most existing methods target the vibration signal; hence, these methods are often unsuitable for use with acoustic emission (AE) sensors. With existing methods, the large sampling rate and high sensitivity of AE sensor causes huge computing costs and susceptibility to noise. To realize sensitive diagnosis with AE sensors, it is necessary to develop a proper band selection algorithm that operates under noisy conditions and with low computing cost. Thus, this paper proposes a segment-based fault information assisted band selection method for AE sensor data. The proposed method is validated by applying it to both simulated and experimental data. The test data contain random impulsive and non-Gaussian noises to represent the signal from other components and electrical noise from the motor system, respectively. With traditional methods, these noises either interrupt the proper band selection or increase the computing cost; however, the proposed method handles these noises and provides proper band selection with moderate computing cost.
      PubDate: 2022-09-15
       
  • An improved semi-active structural control combining optimized fuzzy
           controller with inverse modeling technique of MR damper

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      Abstract: Abstract An effective and robust semi-active control scheme using MR damper for mitigating the earthquake-induced structural responses is proposed in this study. In the first place, a human-designed fuzzy logic controller is developed, in which the uniformly distributed membership functions are adopted for both input and output variables, and the fuzzy rules are formulated based on the law of the fundamental vibration mode. Next, an inverse modeling technique is developed for identifying the input current of MR damper based on the modified Bingham-plastic model. To simultaneously mitigate the seismic responses and guide the MR damper selection, the multiobjective NSGA-II-based approach is applied. The human-designed fuzzy logic controller is then optimized, in which the parameters in the output variable range, membership functions, and the rule base are defined as the design variables. By taking into account different parameter combinations, a variety of Pareto-optimal solutions are derived, based on which the influences of the membership function’s type and symmetry, as well as the rule base’s symmetry on the control performance, are analyzed. Finally, the improved semi-active control systems have been constructed for both linear and nonlinear structures by combining the optimized fuzzy controller with the proposed inverse modeling technique of MR damper. Numerical results have demonstrated the effectiveness and robustness of the proposed semi-active control scheme to the uncertainties associated with structural properties and seismic excitations.
      PubDate: 2022-09-15
       
  • Multi material topology and stacking sequence optimization of composite
           laminated plates

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      Abstract: Abstract Designers and engineers are constantly seeking for more efficient structures that can achieve a high performance with minimum weight. Since its inception, topology optimization has been evolving and new features and methods have been proposed to support the development of such lightweight and high-performance structures. In recent years, the application of multiple-material topology optimization in the conceptual design as well as the consideration of composite materials in the topology optimization process has increased. Composite materials usually offer a superior stiffness-to-weight ratio compared to isotropic materials, but it also requires engineers to define the lamination layup. The lamination stacking sequence can also be optimized through different methods, nevertheless the combination of stacking sequence and topology optimization is still limited in the literature. Therefore, the present paper presents a method to simultaneously optimize the material placement, selection and stacking sequence of composite plates in a multi-material topology optimization framework. The methodology considers that the macro-mechanical composite material response is governed by the orientation of the layers and the composite material properties. As a result, the optimum material placement and selection depend on the material layup that is defined along with the optimization process. A series of example problems are presented and discussed to demonstrate the proposed algorithm capabilities.
      PubDate: 2022-09-15
       
  • Topology optimization of uniform thickness structures using discrete
           object projection

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      Abstract: Abstract Topology optimization (TO) is well suited to exploit the geometric freedom provided by additive manufacturing (AM), but only when the two technologies are properly integrated. Failure to account for the manufacturing process in the execution of the optimization formulation can lead to performance loss and increased production time and/or cost. This paper discusses a TO methodology motivated by the unique features of wire and filament based AM processes with high deposition rates where a constant thickness of deposited features is desired to manage heat flow and path planning during fabrication. In addition to typical manufacturing constraints such as minimum feature size and feature separation, the proposed approach utilizes discrete object projection to impose a constant thickness requirement on all structural features, including structural members and connection points (joints). The mathematical consistency of the developed framework enables the use of gradient-based optimizers, and tradeoffs between design freedom and computational cost are discussed. Although the technique was developed with a specific electron beam fabrication process in mind, it is readily extendable to other AM technologies with similar requirements as well as to create lattice-like designs. The approach is demonstrated on benchmark minimum compliance problems and is shown to successfully design structural components that are directly manufacturable.
      PubDate: 2022-09-15
       
 
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