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  Subjects -> ENGINEERING (Total: 2070 journals)
    - CHEMICAL ENGINEERING (171 journals)
    - CIVIL ENGINEERING (161 journals)
    - ELECTRICAL ENGINEERING (88 journals)
    - ENGINEERING (1148 journals)
    - ENGINEERING MECHANICS AND MATERIALS (320 journals)
    - HYDRAULIC ENGINEERING (52 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (78 journals)

CIVIL ENGINEERING (161 journals)                  1 2     

ACI Structural Journal     Full-text available via subscription   (Followers: 8)
Acta Polytechnica : Journal of Advanced Engineering     Open Access  
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 30)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 20)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 20)
Architectural Engineering     Open Access   (Followers: 3)
Archives of Civil Engineering     Open Access   (Followers: 8)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 1)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 4)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 2)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 9)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 5)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bioinspired Materials     Open Access  
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 12)
Building and Environment     Hybrid Journal   (Followers: 12)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 14)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 4)
Cement and Concrete Composites     Hybrid Journal   (Followers: 9)
Change Over Time     Full-text available via subscription   (Followers: 3)
Civil and Environmental Research     Open Access   (Followers: 13)
Civil Engineering     Hybrid Journal   (Followers: 11)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 5)
Civil Engineering and Architecture     Open Access   (Followers: 3)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 5)
Civil Engineering and Technology     Open Access   (Followers: 4)
Civil Engineering Dimension     Open Access   (Followers: 4)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 72)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 9)
Computers & Structures     Hybrid Journal   (Followers: 25)
Concrete Research Letters     Open Access   (Followers: 2)
Constructii : Journal of Civil Engineering Research     Open Access   (Followers: 9)
Construction Engineering     Open Access   (Followers: 3)
Construction Management and Economics     Hybrid Journal   (Followers: 28)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 13)
Enfoque UTE     Open Access   (Followers: 2)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 4)
Engineering Structures     Hybrid Journal   (Followers: 14)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 16)
Environmental Geotechnics     Open Access  
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 4)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 13)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access   (Followers: 1)
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 5)
Geomaterials     Open Access   (Followers: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 3)
Geotechnik     Hybrid Journal   (Followers: 1)
Géotechnique Letters     Hybrid Journal   (Followers: 4)
HBRC Journal     Open Access   (Followers: 2)
HVAC&R Research     Hybrid Journal   (Followers: 1)
Indoor and Built Environment     Hybrid Journal   (Followers: 1)
Infrastructure Asset Management     Full-text available via subscription  
Ingenio Magno     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 4)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 2)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 7)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 6)
International Journal of Construction Engineering and Management     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription  
International Journal of Protective Structures     Full-text available via subscription   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 4)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 7)
International Journal of Structural Integrity     Hybrid Journal  
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Built Environment     Open Access   (Followers: 2)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 7)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 1)
ISRN Civil Engineering     Open Access   (Followers: 4)
ISRN Power Engineering     Open Access   (Followers: 1)
Journal of Accessibility and Design for All     Open Access   (Followers: 6)
Journal of Advanced Research in Civil and Environmental Engineering     Open Access   (Followers: 1)
Journal of Applied Fire Science     Full-text available via subscription   (Followers: 2)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 15)
Journal of Building Materials and Structures     Open Access  
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 3)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Science     Open Access   (Followers: 12)
Journal of Civil Engineering Research     Open Access   (Followers: 11)
Journal of Civil Society     Hybrid Journal   (Followers: 2)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 2)
Journal of Composites     Open Access   (Followers: 16)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 10)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 20)
Journal of Construction Engineering     Open Access   (Followers: 3)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 21)
Journal of Construction Engineering, Technology & Management     Full-text available via subscription   (Followers: 3)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 7)

        1 2     

Journal Cover   Structural and Multidisciplinary Optimization
  [SJR: 1.273]   [H-I: 54]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1615-1488 - ISSN (Online) 1615-147X
   Published by Springer-Verlag Homepage  [2300 journals]
  • A study of graphics hardware accelerated particle swarm optimization with
           digital pheromones
    • Abstract: Abstract Programmable Graphics Processing Units (GPUs) have lately become a promising means to perform scientific computations. Modern GPUs have proven to outperform the number of floating point operations when compared to traditional Central Processing Units (CPUs) through inherent data parallel architecture and higher bandwidth capabilities. They allow scientific computations to be performed without noticeable degradation in accuracy in a fraction of the time compared to traditional CPUs at substantially reduced costs, making them viable alternatives to expensive computer clusters or workstations. GPU programmability however, has fostered the development of a variety of programming languages making it challenging to select a computing language and use it consistently without the pitfall of being obsolete. Some GPU languages are hardware specific and are designed to rake in performance boosts when used with their host GPUs (e.g., Nvidia Cuda). Others are operating system specific (e.g., Microsoft HLSL). A few are platform agnostic lending themselves to be used on a workstation with any CPU and a GPU (e.g., GLSL, OpenCL). Of a number of companies and organizations that implement formal optimization into their processes, only a few utilize GPUs. It is either because the others are either vested much into CPU based computing or they are not fully aware of the benefits of implementing population based optimization routines in GPUs. Literature shows a large number of research publications specifically in the field of optimization utilizing GPUs. However, most of them are limited to a specific GPU hardware or addressed specific problems. The diversity in current GPU hardware and software APIs present overwhelming number of choices making it challenging to decide where and how to begin transitioning to GPU based computing, impeding promising computing avenues that relatively is very cost effective. In this paper, the authors precisely intend to address some of these issues by broadly classifying GPU APIs into three categories: 1) Hardware vendor dependent GPU APIs, 2) Graphical in context APIs, and 3) Platform agnostic APIs. Prior work by the authors demonstrated the capability of digital pheromones within Particle Swarm Optimization (PSO) for searching n-dimensional design spaces with improved accuracy, efficiency and reliability in serial and parallel CPU computing environments. To study the impact of GPUs, the authors have taken this digital pheromone variant of PSO and implemented it on three GPU APIs, each representing a category listed above, in a simplistic sense – delegate unconstrained explicit objective function evaluations to GPUs. While this approach itself cannot be considered novel, the takeaways from implementing it on different GPU APIs provided a wealth of information that the authors believe can help optimization companies and organizations make informed decisions in implementing GPUs in their processes.
      PubDate: 2015-01-21
       
  • Alpha shape based design space decomposition for island failure regions in
           reliability based design
    • Abstract: Abstract Treatment of uncertainties in structural design involves identifying the boundaries of the failure domain to estimate reliability. When the structural responses are discontinuous or highly nonlinear, the failure regions tend to be an island in the design space. The boundaries of these islands are to be approximated to estimate reliability and perform optimization. This work proposes Alpha (α) shapes, a computational geometry technique to approximate such boundaries. The α shapes are simple to construct and only require Delaunay Tessellation. Once the boundaries are approximated based on responses sampled in a design space, a computationally efficient ray shooting algorithm is used to estimate the reliability without any additional simulations. The proposed approach is successfully used to decompose the design space and perform Reliability based Design Optimization of a tube impacting a rigid wall and a tuned mass damper.
      PubDate: 2015-01-18
       
  • Combining topology and lamination parameter optimisation
    • Abstract: Abstract Two dimensional composite structures are designed for maximum stiffness under multiple load cases. Both the topology and the fibre angle distribution are optimised simultaneous. To solve the topology optimisation, a density approach is used. The stiffness is parametrised in terms of lamination parameters, not directly in terms of the fibre angles. To force the fictitious density to either zero or one both implicit and explicit penalisation are used. Both penalisation approaches are implemented and both give a satisfactory result. Once the optimum lamination parameter and density distribution is found, some post-processing steps are necessary: the boundaries of the structure are determined by post-processing the density distribution. The fibre angle distribution is found by matching the lamination parameter distribution. Finally the fibre paths are determined. A number of examples are worked out to demonstrate the technique for balanced, unbalanced, single and multiple load case problems. The results show that the proposed technique is widely applicable and that there are considerable benefits in exten ding topology optimisation to handle composites.
      PubDate: 2015-01-18
       
  • On Chebyshev’s method for topology optimization of Stokes flows
    • Abstract: Abstract We present a locally cubically convergent algorithm for topology optimization of Stokes flows based on a Chebyshev’s iteration globalized with Armijo linesearch. The characteristic features of the method include the low computational complexity of the search direction calculation, evaluation of the objective function and constraints needed in the linesearch procedure as well as their high order derivatives utilized for obtaining higher order rate of convergence. Both finite element and finite volumes discretizations of the algorithm are tested on the standard two-dimensional benchmark problems, in the case of finite elements both on structured and quasi-uniform unstructured meshes of quadrilaterals. The algorithm outperforms Newton’s method in nearly all test cases. Finally, the finite element discretization of the algorithm is tested within a continuation/adaptive mesh refinement framework.
      PubDate: 2015-01-16
       
  • Shifted robust multi-objective test problems
    • Abstract: Abstract In 2013 Gaspar-Cunha et al. proposed a set of novel robust multi-objective benchmark functions to increase the difficulty of the current test problems and effectively mimic the characteristics of real search spaces. Despite the merits of the proposed benchmark problems, it is observed that the robust Pareto optimal fronts are located on the boundaries of the search space, which may result in the infeasibility of solutions obtained in case of perturbations along the negative side of the second parameter. This paper modifies the proposed test functions by Gaspar-Cunha et al. to mimic real problems better and allow the parameters to be fluctuated by any degree of perturbations. In fact, the robust fronts are shifted to the centre of the search space, so that any degree of uncertainties can be considered. The paper considers theoretical and experimental analysis of both set of test functions as well.
      PubDate: 2015-01-15
       
  • Advanced approximations for sequential optimization with discrete material
           interpolations
    • Abstract: Abstract The DMO (discrete material optimization) technique is employed in structural synthesis dealing with the selection of a material belonging to a group of candidate materials. It has mainly been employed in the optimization for orientation of layers of composite laminates. The DMO is based on an interpolation in the form of a weighted sum of candidate materials. The weights are nonlinear functions of penalized design variables that are solved by continuous optimization, leading to proper material selection. The preferred way of solution has been by sequential approximate optimization (SAO), based on Taylor series approximations (TSA) as surrogate functions of the structural responses. However, due to the complexity of the DMO formulation the classical local surrogate techniques become of questionable efficiency in adequately capturing structural response behavior. To improve the quality of the surrogate models, it is here proposed the use of the weighting functions to form intermediate design variables in terms of which a higher quality TSA is created. Improvements in the convergence characteristics of the SAO is observed, opening new perspectives to the efficient application of the DMO concept.
      PubDate: 2015-01-11
       
  • Hierarchical topology optimization addressing material design constraints
           and application to sandwich-type structures
    • Abstract: Abstract The hierarchical topology optimization model for multiscale design of structures addresses the problem of finding optimal material distributions at different but interconnected structural length scales with the objective of optimally design the structure and its material. In this work some new developments on this model are presented. An algorithm is mounted to address specific features of multiscale design such as multiple material design constrains. Furthermore, previous design parameterizations assume micro design variables associated with each finite element, trying to approximate a pointwise optimal material definition, and leading to very efficient designs but of problematic manufacturability. Here one reduces the total number of problem design variables by assuming a design parameterization where the design is uniform within mechanically consistent larger subdomains—“design subdomains”. This eases applicability, manufacturability, and is a very effective approach for practical design problems involving for example sandwich-type structures, where larger subdomains identify structural constituents such as a soft core between two solid face-sheets. The parameterization to include “design subdomains” and the introduction of local material design constraints requires an appropriate derivation of the optimality conditions. The main structural applications presented here are related to sandwich type of structures. The influence of the designer choices for “design subdomains” characterizing the macrostructure, and “material unit cell” representing the microstructure, will also be studied in the solutions obtained. The examples show the effectiveness of the methodology presented to fully benefit from an enlarged design space incorporating structural and material designs, and thus efficiently maximize the mechanical component structural performance.
      PubDate: 2015-01-09
       
  • Minimal compliance topologies for maximal buckling load of columns
    • Abstract: Abstract This paper presents a new approach to the topology optimization of columns exposed to a loss of stability. The idea is to replace a conventional maximization of a buckling load by a locally formulated topology optimization problem based on compliance minimization. In order to do this, the standard instability analysis of a compressed column is performed first and the buckling mode is determined. Then the compressive loading is replaced by a transverse one which is selected so as to generate a bending moment, the distribution of which coincides with the one representing the considered buckling mode. Minimization of compliance is performed for the bent structure and optimal topology is generated. Finally, the critical load for the optimal column is calculated. The selected numerical results obtained with the use of the above technique, under the assumption that the buckling load is unimodal, are presented. The above approach allows generating optimal topologies using Cellular Automata (CA) method, which by nature requires local formulation of the design problem.
      PubDate: 2015-01-08
       
  • A comparative study of dynamic analysis methods for structural topology
           optimization under harmonic force excitations
    • Abstract: Abstract This work is focused on the topology optimization related to harmonic responses for large-scale problems. A comparative study is made among mode displacement method (MDM), mode acceleration method (MAM) and full method (FM) to highlight their effectiveness. It is found that the MDM results in the unsatisfactory convergence due to the low accuracy of harmonic responses, while MAM and FM have a good accuracy and evidently favor the optimization convergence. Especially, the FM is of superiority in both accuracy and efficiency under the excitation at one specific frequency; MAM is preferable due to its balance between the computing efficiency and accuracy when multiple excitation frequencies are taken into account.
      PubDate: 2015-01-08
       
  • Efficient adaptive response surface method using intelligent space
           exploration strategy
    • Abstract: Abstract This article presents a novel intelligent space exploration strategy (ISES), which is then integrated with the adaptive response surface method (ARSM) for higher global optimization efficiency. ISES consists of two novel elements for space reduction and sequential sampling: i) Significant design space (SDS) identification algorithm, which is developed to identify the promising design space and balance local exploitation and global exploration during the search, and ii) An iterative maximin sequential Latin hypercube design (LHD) sampling scheme and tailored termination criteria. Moreover, an adaptive penalty method is developed for handling expensive constraints. The new global optimization strategy, notated as ARSM-ISES, is then tested with numerical benchmark problems on optimization efficiency, global convergence, robustness, and algorithm execution overhead. Comparative results show that ARSM-ISES not only outperforms the original ARSM and IARSM, in general it also converges to better optima with fewer function evaluations and less algorithm execution time as compared to state-of-the-art metamodel-based design optimization algorithms including MPS, EGO, and MSEGO. For high dimensional (HD) problems, ARSM-ISES shows promises as it performs better on chosen test problems than TR-MPS, which is especially designed for solving HD problems. ARSM-ISES is then applied to the optimal design of a lifting surface of hypersonic flight vehicles. Finally, main features and limitations of the proposed algorithm are discussed.
      PubDate: 2015-01-08
       
  • Some considerations regarding the use of multi-fidelity Kriging in the
           construction of surrogate models
    • Abstract: Abstract Surrogate models or metamodels are commonly used to exploit expensive computational simulations within a design optimization framework. The application of multi-fidelity surrogate modeling approaches has recently been gaining ground due to the potential for further reductions in simulation effort over single fidelity approaches. However, given a black box problem when exactly should a designer select a multi-fidelity approach over a single fidelity approach and vice versa? Using a series of analytical test functions and engineering design examples from the literature, the following paper illustrates the potential pitfalls of choosing one technique over the other without a careful consideration of the optimization problem at hand. These examples are then used to define and validate a set of guidelines for the creation of a multi-fidelity Kriging model. The resulting guidelines state that the different fidelity functions should be well correlated, that the amount of low fidelity data in the model should be greater than the amount of high fidelity data and that more than 10 % and less than 80 % of the total simulation budget should be spent on low fidelity simulations in order for the resulting multi-fidelity model to perform better than the equivalent costing high fidelity model.
      PubDate: 2014-12-28
       
  • Optimal design of welded structure with structural and local-notch
           stresses based on International Institute of Welding recommendations
    • Abstract: Abstract A procedure for optimally designing light-weight and reliable welded structures is proposed and applied to the structural design of an illustrative welded structure used in construction and transportation machinery. To verify the effectiveness of the design procedure, the designed structures were experimentally produced, and then the fatigue lives of them were evaluated. The proposed design procedure is composed of two major processes; one is thickness-design process, and the other one is the process for designing weld type. Since the design for thickness and weld type is conducted sequentially, the thickness of welded structures can be determined in an optimization process without considering weld type; hence, the proposed design procedure is not computational demanding. In the thickness-design process, the thickness of a target welded structure is optimized by constraining structural stress that is estimated on the basis of the International Institute of Welding recommendations. After the thickness optimization, weld type of welded joints is designed by using local-notch stress, which is also defined in the IIW recommendations. Two kinds of test pieces based on the designed welded structure were experimentally produced by changing the weld type of a joint, and the test pieces were fatigue tested to verify their fatigue resistance. Since the produced welded structures had expected fatigue resistance, it can be concluded that welded structures can be optimally designed by using the proposed design procedure.
      PubDate: 2014-12-20
       
  • The ESO method revisited
    • Abstract: Abstract This paper examines the evolutionary structural optimisation (ESO) method and its shortcomings. By proposing a problem statement for ESO followed by an accurate sensitivity analysis a framework is presented in which ESO is mathematically justifiable. It is shown that when using a sufficiently accurate sensitivity analysis, ESO method is not prone to the problem proposed by Zhou and Rozvany (Struct Multidiscip Optim 21(1):80–83, 2001). A complementary discussion on previous communications about ESO and strategies to overcome the Zhou-Rozvany problem is also presented. Finally it is shown that even the proposed rigorous ESO approach can result in highly inefficient local optima. It is discussed that the reason behind this shortcoming is ESO’s inherent unidirectional approach. It is thus concluded that the ESO method should only be used on a very limited class of optimisation problems where the problem’s constraints demand a unidirectional approach to final solutions. It is also discussed that the Bidirectional ESO (BESO) method is not prone to this shortcoming and it is suggested that the two methods be considered as completely separate optimisation techniques.
      PubDate: 2014-12-20
       
  • Discrete thickness optimization via piecewise constraint penalization
    • Abstract: Abstract Structural engineers are often constrained by cost or manufacturing considerations to select member thicknesses from a discrete set of values. Conventional, gradient-free techniques to solve these discrete problems cannot handle large problem sizes, while discrete material optimization (DMO) techniques may encounter difficulties, especially for bending-dominated problems. To resolve these issues, we propose an efficient gradient-based technique to obtain engineering solutions to the discrete thickness selection problem. The proposed technique uses a series of constraints to enforce an effective stiffness-to-mass and strength-to-mass penalty on intermediate designs. In conjunction with these constraints, we apply an exact penalty function which drives the solution towards a discrete design. We utilize a continuation approach to obtain approximate solutions to the discrete thickness selection problem by solving a sequence of relaxed continuous problems with increasing penalization. We also show how this approach can be applied to combined discrete thickness selection and topology optimization design problems. To demonstrate the effectiveness of the proposed technique, we present both compliance and stress-constrained results for in-plane and bending-dominated problems.
      PubDate: 2014-12-20
       
  • 3D interactive topology optimization on hand-held devices
    • Abstract: Abstract This educational paper describes the implementation aspects, user interface design considerations and workflow potential of the recently published TopOpt 3D App. The app solves the standard minimum compliance problem in 3D and allows the user to change design settings interactively at any point in time during the optimization. Apart from its educational nature, the app may point towards future ways of performing industrial design. Instead of the usual geometrize, then model and optimize approach, the geometry now automatically adapts to the varying boundary and loading conditions. The app is freely available for iOS at Apple’s App Store and at http://www.topopt.dtu.dk/TopOpt3D for Windows and OSX.
      PubDate: 2014-12-20
       
  • Design of phononic crystals for self-collimation of elastic waves using
           topology optimization method
    • Abstract: Abstract Self-collimating phononic crystals (PCs) are periodic structures that enable self-collimation of waves. While various design parameters such as material property, period, lattice symmetry, and material distribution in a unit cell affect wave scattering inside a PC, this work aims to find an optimal material distribution in a unit cell that exhibits the desired self-collimation properties. While earlier studies were mainly focused on the arrangement of self-collimating PCs or shape changes of inclusions in a unit cell having a specific topological layout, we present a topology optimization formulation to find a desired material distribution. Specifically, a finite element based formulation is set up to find the matrix and inclusion material distribution that can make elastic shear-horizontal bulk waves propagate along a desired target direction. The proposed topology optimization formulation newly employs the geometric properties of equi-frequency contours (EFCs) in the wave vector space as essential elements in forming objective and constraint functions. The sensitivities of these functions with respect to design variables are explicitly derived to utilize a gradient-based optimizer. To show the effectiveness of the formulation, several case studies are considered.
      PubDate: 2014-12-14
       
  • Modeling of global and local stability in optimization of truss-like
           structures using frame elements
    • Abstract: Abstract An approach to take into account global and local stability in the design optimization of truss-like structures is presented. It is based on the use of frame elements and a single global stability constraint. A detailed discussion on key aspects of the proposed approach is presented, together with numerical examples. The proposed approach ensures global stability and does not require the use of Euler formula, avoiding several difficulties encountered in truss optimization. Besides, the examples illustrate that global stability is an important aspect to be taken into account in most practical cases.
      PubDate: 2014-12-14
       
  • Experiment and multiobjective optimization design of tape-spring hinges
    • Abstract: Abstract Flexible tape-spring hinges can be folded elastically and are able to self-deploy by releasing stored strain energy with fewer component parts and slight weights. This study presents a detailed investigation of the folding and deployment of single-layer tape-spring (SLTS) hinges and double-layer tape-spring (DLTS) hinges under pure bend loading. The material properties of tape-spring hinges are measured using an INSTRON machine. A DLTS hinge construction is created, and its moment-rotation relationship during quasi-static deployment is measured. An experiment is conducted to verify the validation of the numerical models for the DLTS hinges. The quasi-static deployment behavior of SLTS hinges and DLTS hinges is then analyzed using nonlinear finite element ABAQUS/Explicit solver, starting from the complete folded configuration. The DLTS hinge has good quasi-static deployment performances with regard to maximum stress (S m ), steady moment (M *) and the peak moment (M d ) during the DLTS hinge quasi-static deployment. In addition, the sampling designs of the DLTS hinges are created based on a three-level full factorial design of experiments (DOE) method. The surrogate models of S m , M * and M d of the DLTS hinges are derived using response surface method (RSM) to reduce the computational cost of quasi-static folding and deployment of numerical simulations. The Multiobjective optimization design (MOD) of the DLTS hinge is performed using modified non-dominated sorting genetic algorithm (NSGA-II) algorithm to achieve the optimal design. The finite element models for the optimal design based on numerical method are established to validate the optimization results.
      PubDate: 2014-12-14
       
  • Multi-fidelity information fusion based on prediction of kriging
    • Abstract: Abstract In this paper, a novel kriging-based multi-fidelity method is proposed. Firstly, the model uncertainty of low-fidelity and high-fidelity models is quantified. On the other hand, the prediction uncertainty of kriging-based surrogate models(SM) is confirmed by its mean square error. After that, the integral uncertainty is acquired by math modeling. Meanwhile, the SMs are constructed through data from low-fidelity and high-fidelity models. Eventually, the low-fidelity (LF) and high-fidelity (HF) SMs with integral uncertainty are obtained and a proposed fusion algorithm is implemented. The fusion algorithm refers to the Kalman filter’s idea of optimal estimation to utilize the independent information from different models synthetically. Through several mathematical examples implemented, the fused SM is certified that its variance is decreased and the fused results tend to the true value. In addition, an engineering example about autonomous underwater vehicles’ hull design is provided to prove the feasibility of this proposed multi-fidelity method in practice. In the future, it will be a helpful tool to deal with reliability optimization of black-box problems and potentially applied in multidisciplinary design optimization.
      PubDate: 2014-12-13
       
  • Filter the shape sensitivity in level set-based topology optimization
           methods
    • Abstract: Abstract Filtering methods are widely used in density-based topology optimization methods, such as the SIMP method, to prevent checkerboards and mesh dependency due to their ease of implementation and their efficiency. In this study, several filtering schemes are presented to filter the shape sensitivity in level set-based structural topology optimization methods. It is revealed that filtering of the shape sensitivity can yield convergence with less iterations without considerably increasing the computing time of each iteration step. Thus, it can improve the overall computational efficiency. The validity of the method is tested on both the mean compliance minimization problem and the compliant mechanisms design problem.
      PubDate: 2014-12-13
       
 
 
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