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Showing 1 - 0 of 0 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 12)
Acta Polytechnica : Journal of Advanced Engineering     Open Access  
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 1)
Advances in Civil Engineering     Open Access   (Followers: 31)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 23)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 24)
Architectural Engineering     Open Access   (Followers: 4)
Archives of Civil Engineering     Open Access   (Followers: 8)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access  
ATBU Journal of Environmental Technology     Open Access   (Followers: 2)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 5)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 8)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 4)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bioinspired Materials     Open Access   (Followers: 2)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 13)
Building and Environment     Hybrid Journal   (Followers: 14)
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 14)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 4)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 9)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 4)
Case Studies in Structural Engineering     Open Access   (Followers: 7)
Cement and Concrete Composites     Hybrid Journal   (Followers: 14)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 4)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 6)
Civil And Environmental Engineering Reports     Open Access   (Followers: 4)
Civil and Environmental Research     Open Access   (Followers: 15)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 11)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 2)
Civil Engineering and Technology     Open Access   (Followers: 9)
Civil Engineering Dimension     Open Access   (Followers: 8)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 218)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 8)
Computers & Structures     Hybrid Journal   (Followers: 28)
Concrete Research Letters     Open Access   (Followers: 3)
Construction Economics and Building     Open Access   (Followers: 1)
Construction Engineering     Open Access   (Followers: 6)
Construction Management and Economics     Hybrid Journal   (Followers: 18)
Construction Science     Open Access   (Followers: 2)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 1)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 14)
Enfoque UTE     Open Access   (Followers: 1)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 5)
Engineering Structures     Hybrid Journal   (Followers: 12)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 1)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 12)
Environmental Geotechnics     Hybrid Journal   (Followers: 3)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 6)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 13)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 1)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 1)
Géotechnique Letters     Hybrid Journal   (Followers: 4)
HBRC Journal     Open Access   (Followers: 1)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indoor and Built Environment     Hybrid Journal   (Followers: 1)
Infrastructure Asset Management     Hybrid Journal   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 16)
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: 13)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 8)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 1)
International Journal of Construction Engineering and Management     Open Access   (Followers: 4)
International Journal of Geo-Engineering     Open Access  
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Masonry Research and Innovation     Hybrid Journal  
International Journal of Pavement Research and Technology     Open Access   (Followers: 2)
International Journal of Protective Structures     Full-text available via subscription   (Followers: 4)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 10)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 6)
International Journal of Sustainable Built Environment     Open Access   (Followers: 3)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 7)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 4)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 15)
Journal of Building Engineering     Hybrid Journal  
Journal of Building Materials and Structures     Open Access   (Followers: 1)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 9)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Science     Open Access   (Followers: 8)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Society     Hybrid Journal   (Followers: 3)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 3)
Journal of Composites     Open Access   (Followers: 77)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 12)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 22)
Journal of Construction Engineering     Open Access   (Followers: 5)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 19)
Journal of Construction Engineering, Technology & Management     Full-text available via subscription   (Followers: 2)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 6)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 2)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 5)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 3)
Journal of Green Building     Full-text available via subscription   (Followers: 10)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 11)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 19)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 4)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 10)
Journal of Multifunctional Composites     Full-text available via subscription   (Followers: 4)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 8)
Journal of Offshore Structure and Technology     Full-text available via subscription  
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 4)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 7)
Journal of Rehabilitation in Civil Engineering     Open Access  
Journal of Solid Waste Technology and Management     Full-text available via subscription  
Journal of Structural Engineering     Full-text available via subscription   (Followers: 37)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Structures     Open Access   (Followers: 2)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 1)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 4)
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 1)
Latin American Journal of Solids and Structures     Open Access   (Followers: 1)
Materiales de Construcción     Open Access  
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 12)
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 6)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 2)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 4)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 6)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 11)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 6)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 3)
Random Structures and Algorithms     Hybrid Journal   (Followers: 3)
Recent Trends In Civil Engineering & Technology     Full-text available via subscription   (Followers: 2)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 4)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 7)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 3)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 56)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 1)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 1)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 8)
Structural Concrete     Hybrid Journal   (Followers: 9)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 6)
Structural Engineering International     Full-text available via subscription   (Followers: 10)
Structural Safety     Hybrid Journal   (Followers: 7)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 24)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 9)
Structures     Hybrid Journal  
Study of Civil Engineering and Architecture     Open Access   (Followers: 7)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access  
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 5)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 5)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 1)
Thin-Walled Structures     Hybrid Journal   (Followers: 2)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Water Science & Technology     Partially Free   (Followers: 22)
Water Science and Technology : Water Supply     Partially Free   (Followers: 20)


Journal Cover Structural and Multidisciplinary Optimization
  [SJR: 1.825]   [H-I: 61]   [8 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  [2334 journals]
  • Metamodel selection based on stepwise regression
    • Authors: XiaoJian Zhou; Ting Jiang
      Abstract: Abstract Metamodels are often used to replace expensive simulations of engineering problems. When a training set is given, a series of metamodels can be constructed, and then there are two strategies to deal with these metamodels: (1) picking out the best one with the highest accuracy as an approximation of the computationally intensive simulation; and (2) combining all of them into an ensemble model. However, since the choice of approximate model depends on design of experiments (DOEs), employing of the first strategy thus increases the risk of adopting an inappropriate model. Nevertheless, the second strategy also seems not to be a good choice, since adding redundant metamodels may lead to loss of accuracy. Therefore, it is a necessary step to eliminate the redundant metamodels from the set of the candidates before constructing the final ensemble. Illuminated by the method of variable selection widely used in polynomial regression, a metamodel selection method based on stepwise regression is proposed. In our method, just a subset of n ones (n ≤ p, where p is the number of all of the candidate metamodels) is used. In addition, a new ensemble technique is proposed from the view of polynomial regression in this work. This new ensemble technique, combined with metamodel selection method, has been evaluated using six benchmark problems. The results show that eliminating the redundant metamodels before constructing the ensemble can provide more ideal prediction accuracy than directly constructing the ensemble by utilizing all of the candidates.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1442-1
  • Topology optimization for crashworthiness of thin-walled structures under
           axial impact using hybrid cellular automata
    • Authors: Fabian Duddeck; Stephan Hunkeler; Pablo Lozano; Erich Wehrle; Duo Zeng
      Abstract: Abstract Although topology optimization is well established in most engineering fields, it is still in its infancy concerning highly non-linear structural applications like vehicular crashworthiness. One of the approaches recently proposed and based on Hybrid Cellular Automata is modified here such that it can be applied for the first time to thin-walled structures. Classical methods based on voxel techniques, i.e., on solid three-dimensional volume elements, cannot derive structures made from thin metal sheets where the main energy absorption mode is related to plastic buckling, folding and failure. Because the main components of car structures are made from such thin-walled beams and panels, a special approach using SFE CONCEPT was developed, which is presented in this paper.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1445-y
  • Evolutionary topological design for phononic band gap crystals
    • Authors: Yang fan Li; Xiaodong Huang; Fei Meng; Shiwei Zhou
      Abstract: Abstract Phononic band gap crystals are made of periodic inclusions embedded in a base material, which can forbid the propagation of elastic and acoustic waves within certain range of frequencies. In the past two decades, the systematic design of phononic band gap crystals has attracted increasing attention due to their wide practical applications such as sound insulation, waveguides, or acoustic wave filtering. This paper proposes a new topology optimization algorithm based on bi-directional evolutionary structural optimization (BESO) method and finite element analysis for the design of phononic band gap crystals. The study on the maximizing gap size between two adjacent bands has been systematically conducted for out-of-plane waves, in-plane waves and the coupled in-plane and out-of-plane waves. Numerical results demonstrate that the proposed optimization algorithm is effective and efficient for the design of phononic band gap crystals and various topological patterns of optimized phononic structures are presented. Several new patterns for phononic band gap crystals have been successfully obtained.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1424-3
  • Reliability-based topology optimization using a new method for sensitivity
           approximation - application to ground structures
    • Authors: Ke Liu; Glaucio H. Paulino; Paolo Gardoni
      Abstract: Abstract This paper proposes an efficient gradient-based optimization approach for reliability-based topology optimization of structures under uncertainties. Our objective is to find the optimized topology of structures with minimum weight which also satisfy certain reliability requirements. In the literature, those problems are primarily performed with approaches that use a first-order reliability method (FORM) to estimate the gradient of the probability of failure. However, these approaches may lead to deficient or even invalid results because the gradient of probabilistic constraints, calculated by first order approximation, might not be sufficiently accurate. To overcome this issue, a newly developed segmental multi-point linearization (SML) method is employed in the optimization approach for a more accurate estimation of the gradient of failure probability. Meanwhile, this implementation also improves the approximation of the probability evaluation at no extra cost. In general, adoption of the SML method leads to a more accurate and robust approach. Numerical examples show that the new approach, based on the SML method, is numerically stable and usually provides optimized structures that have more of the desired features than conventional FORM-based approaches. The present approach typically does not lead to a fully stressed design, and thus this feature will be verified by numerical examples.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1422-5
  • Multi-objective topology and sizing optimization of bus body frame
    • Authors: Wei Zhong; Ruiyi Su; Liangjin Gui; Zijie Fan
      Abstract: Abstract A genetic algorithm based method for multi-objective topology and sizing optimization of bus body frame with manufacturing constraints is presented, where a flexible strategy called independent ground structures is introduced to define different ground structures for topology optimization and sizing optimization. The finite element models of an integral bus body frame were created and validated by physical experiments, including modal test and static strength test. The formulation of multi-objective optimization is established, where the objectives are to minimize the mass, maximize the torsional stiffness and maximize the first frequency of the bus body, and the constraints include strength, symmetry and consistency. The proposed method was implemented, and the roof frame of the integral bus was chosen as the design space. A set of non-dominated solutions was obtained, among which 41 new structures are strictly better than the benchmark model in all objectives. Two structures respectively with lightest weight and highest torsional stiffness of those 41 structures are shown in the paper. The weight of the former is decreased by 97.9 kg (3.43 %), while the torsional stiffness of the latter is increased by 4.89 kN•m/deg (13.14 %).
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1431-4
  • A multiscale method for optimising surface topography in
           elastohydrodynamic lubrication (EHL) using metamodels
    • Authors: G. N. de Boer; L. Gao; R. W. Hewson; H. M. Thompson; N. Raske; V. V. Toropov
      Abstract: Abstract The frictional performance of a bearing is of significant interest in any mechanical system where there are lubricated surfaces under load and in relative motion. Surface topography plays a major role in determining the coefficient of friction for the bearing because the size of the fluid film and topography are of a comparable order. The problem of optimising topography for such a system is complicated by the separation in scales between the size of the lubricated domain and that of the topography, which is of at least one order of magnitude or more smaller. This paper introduces a multiscale method for optimising the small scale topography for improved frictional performance of the large scale bearing. The approach fully couples the elastohydrodynamic lubrication at both scales between pressure generated in the lubricant and deformation of the bounding surfaces. Homogenised small scale data is used to inform the large scale model and is represented using Moving Least Squares metamodels calibrated by cross validation. An optimal topography for a minimum coefficient of friction for the bearing is identified and comparisons made of local minima in the response, where very different topographies with similar frictional performance are observed. Comparisons of the optimal topography with the smooth surface model demonstrated the complexity of capturing the non-linear effect of topography and the necessity of the multiscale method in capturing this. Deviations from the smooth surface model were quantified by the metamodel coefficients and showed how topographies with a similar frictional performance have very different characteristics.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1412-7
  • A variable-accuracy metamodel-based architecture for global MDO under
    • Authors: Cecilia Leotardi; Andrea Serani; Umberto Iemma; Emilio F. Campana; Matteo Diez
      Abstract: Abstract A method for simulation-based multidisciplinary robust design optimization (MRDO) of problems affected by uncertainty is presented. The challenging aspects of simulation-based MRDO are both algorithmic and computational, since the solution of a MRDO problem typically requires simulation-based multidisciplinary analyses (MDA), uncertainty quantification (UQ) and optimization. Herein, the identification of the optimal design is achieved by a variable-accuracy, metamodel-based optimization, following a multidisciplinary feasible (MDF) architecture. The approach encompasses a variable (i) density of the design of experiments for the metamodel training, (ii) sample size for the UQ analysis by quasi Monte Carlo simulation and (iii) tolerance for the multidisciplinary consistency in MDA. The focus is on two-way steady fluid-structure interaction problem, assessed by partitioned solvers for the hydrodynamic and the structural analysis. Two analytical test problems are shown, along with the design of a racing-sailboat keel fin subject to the stochastic variation of the yaw angle. The method is validated versus a standard MDF approach to MRDO, taken as a benchmark and solved by fully coupled MDA, fully converged UQ, without metamodels. The method is evaluated in terms of optimal design performances and number of simulations required to achieve the optimal solution. For the current application, the optimal configuration shows performances very close to the benchmark solution. The convergence analysis to the optimum shows a promising reduction of the computational cost.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1423-4
  • Comparison study of some commercial structural optimization software
    • Authors: Wook-han Choi; Jong-moon Kim; Gyung-Jin Park
      Abstract: Abstract Mathematical optimization theories are employed for the design of structures in structural optimization. Structural optimization is being widely utilized for practical problems due to well-developed commercial software systems. Three representative structural optimization systems such as Genesis, MSC Nastran and OptiStruct are investigated and evaluated by solving various test examples in different scales. The design capabilities of three software systems are explored and the performances of the systems are compared. The performance of structural optimization depends on the quality of the optimum solution and the computational time, and these aspects are compared from an application viewpoint. For a fair comparison, the same formulations are utilized, and the same optimization methods are employed for each example. Also, the same system environment is prepared, and the same optimization parameters are used. Additionally, various design options of each software system are tested for the best performance. Linear static response size, shape, topology, topometry and topography optimizations are applied to the examples and the results are compared. No system seems to be the best in all cases and each system has advantages and disadvantages depending on the application. In general, Genesis is excellent in computational time while OptiStruct gives excellent optimum solutions, in size, topometry and topology optimizations. Meanwhile, MSC Nastran presents good solutions in shape and topography optimizations.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1429-y
  • Design optimization of a novel NPR crash box based on multi-objective
           genetic algorithm
    • Authors: Guan Zhou; Zheng-Dong Ma; Guangyao Li; Aiguo Cheng; Libin Duan; Wanzhong Zhao
      Abstract: Abstract Possessing the unique properties of lower mass and higher performances, the structure with Negative Poisson’s Ratio (NPR) can be widely used in aerospace and vehicle industry. By combing the NPR structure filled core and the traditional crash box, a novel NPR crash box is first proposed in this work to improve the performances of the crash box. The performances of the novel NPR crash box are fully studied by comparing to the traditional crash box and the aluminum foam filled crash box. A parameterized model of the NPR crash box, which integrates the design parameters of the basic NPR cell structure, is built to improve the analysis and optimization efficiency, the accuracy of the parameterized model is also verified by comparing to traditional FEM model. Multi-objective optimization model of the NPR crash box is established by combining the parameterized model, optimal Latin square design method and response surface model approach. Non-dominated sorting genetic algorithm-II (NSGA-II) is then applied to optimize the design parameters of the basic NPR cell structure to improve the performances of the NPR crash box. The results indicate that the novel NPR crash box can improve the performances of the crash box remarkably and the combination of parameterized model and multi-objective genetic algorithms optimize the NPR crash box efficiently. The presented new method also serves as a good example for other application and optimization of NPR structure.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1452-z
  • An exact reanalysis method for structures with local modifications
    • Authors: Guanxin Huang; Hu Wang; Guangyao Li
      Abstract: Abstract An exact reanalysis method named Indirect Factorization Updating (IFU) is proposed for the structure with local modifications, including boundary modifications. The IFU method is developed from the Independent Coefficients (IC) and Sherman-Morrison-Woodbury (SMW) formula. Due to the local modifications, the modified equations are divided into two parts: balanced equations and unbalanced equations. Using the theory of the IC, extra constraints are enforced on the unbalanced Degree of Freedoms (DOFs), so that the fundamental solution system of the balanced equations can be obtained by using the SMW formula. Then, a unique solution is derived from the general solution of the balanced equations to satisfy the unbalanced equations. In order to use the SMW formula directly, the change of the stiffness matrix is converted to a low-rank form by using the Cholesky factorization of the initial stiffness matrix. The Cholesky factorization is indirectly updated according to the stiffness matrix of the balanced equations but not directly according to the modified equations. Three examples are presented to verify the performance of the suggested IFU method. The results show that the IFU can efficiently obtain the exact solution of the structures with boundary modifications.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1417-2
  • Designing meta material slabs exhibiting negative refraction using
           topology optimization
    • Authors: Rasmus E. Christiansen; Ole Sigmund
      Abstract: Abstract This paper proposes a topology optimization based approach for designing meta materials exhibiting a desired negative refraction with high transmission at a given angle of incidence and frequency. The approach considers a finite slab of meta material consisting of axis-symmetric designable unit cells subjected to an exterior field. The unit cell is designed to achieve the desired properties based on tailoring the response of the meta material slab under the exterior field. The approach is directly applicable to physical problems modeled by the Helmholtz equation, such as acoustic, elastic and electromagnetic wave problems. Acoustic meta materials with unit cell size on the order of half the wave length are considered as examples. Optimized designs are presented and their performance under varying frequency and angle of incidence is investigated.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1411-8
  • Topology optimization of a coupled thermal-fluid system under a tangential
           thermal gradient constraint
    • Authors: Xiaoping Qian; Ercan M. Dede
      Abstract: Abstract This paper presents a continuous adjoint approach for topology optimization of a coupled heat transfer and laminar fluid flow system under tangential thermal gradient (TTG) constraints. In this system, the thermal gradient along the boundary of multiple heat sources needs to be controlled. The design goals are to minimize the temperature of the domain, the fluid power dissipation and the TTG along the boundary of the heat sources. The first two goals are combined into a single cost function with weight variables. The TTG is constrained in one of two forms, an integral form where the integral of TTG squares along the boundaries of heat sources is constrained, or a point-wise form where TTG is constrained point-wise. A gradient-based approach is developed to obtain the optimized designs. A salient feature of our approach is the use of the continuous adjoint approach to derive gradients of both the cost function and two forms of TTG constraints. Numerical examples demonstrate that the continuous adjoint approach leads to successful topological optimization of the constrained thermal-fluid system. The use of TTG constraint is effective in lowering the TTG along the heat source boundaries. The resulting designs exhibit clear black/white contrast.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1421-6
  • Thanks to our Reviewers
    • Authors: Raphael T. Haftka
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1425-2
  • A full-space barrier method for stress-constrained discrete material
           design optimization
    • Authors: Graeme J. Kennedy
      Abstract: Abstract In this paper, we present a full-space barrier method designed for stress-constrained mass minimization problems with discrete material options. The advantages of the full-space barrier method are twofold. First, in the full-space the stress constraints are provably concave, which facilitates the construction of convex subproblems within the optimization algorithm. Second, by using the full-space, it is no longer necessary to employ stress constraint aggregation techniques to reduce adjoint-gradient evaluation costs. The proposed optimization algorithm uses a Newton method where an approximate linearization of the KKT conditions is solved inexactly at each iteration using a preconditioned Krylov subspace method. Sparse constraints that arise in the discrete material parametrization are treated using a null-space method. Results of the proposed algorithm are demonstrated on a series of three topology and multimaterial optimization problems with selection between isotropic and orthotropic materials, as well as discrete ply-angle selection.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1428-z
  • Shape and topology optimization based on the convected level set method
    • Authors: Kentaro Yaji; Masaki Otomori; Takayuki Yamada; Kazuhiro Izui; Shinji Nishiwaki; Olivier Pironneau
      Abstract: Abstract The aim of this research is to construct a shape optimization method based on the convected level set method, in which the level set function is defined as a truncated smooth function obtained by using a sinus filter based on a hyperbolic tangent function. The local property of the hyperbolic tangent function dramatically reduces the generation of red the error between the specified profile of the hyperbolic tangent function and the level set function that is updated using a time evolution equation. In addition, the small size of the error facilitates the use of convective reinitialization, whose basic idea is that the reinitialization is embedded in the time evolution equation, whereas such treatment is typically conducted in a separate calculation in conventional level set methods. The convected level set method can completely avoid the need for additional calculations when performing reinitialization. The validity and effectiveness of our presented method are tested with a mean compliance minimization problem and a problem for the design of a compliant mechanism.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1444-z
  • Implementing a structural continuity constraint and a halting method for
           the topology optimization of energy absorbers
    • Authors: Daniel Stojanov; Brian G. Falzon; Xinhua Wu; Wenyi Yan
      Abstract: Abstract This study investigates topology optimization of energy absorbing structures in which material damage is accounted for in the optimization process. The optimization objective is to design the lightest structures that are able to absorb the required mechanical energy. A structural continuity constraint check is introduced that is able to detect when no feasible load path remains in the finite element model, usually as a result of large scale fracture. This assures that designs do not fail when loaded under the conditions prescribed in the design requirements. This continuity constraint check is automated and requires no intervention from the analyst once the optimization process is initiated. Consequently, the optimization algorithm proceeds towards evolving an energy absorbing structure with the minimum structural mass that is not susceptible to global structural failure. A method is also introduced to determine when the optimization process should halt. The method identifies when the optimization method has plateaued and is no longer likely to provide improved designs if continued for further iterations. This provides the designer with a rational method to determine the necessary time to run the optimization and avoid wasting computational resources on unnecessary iterations. A case study is presented to demonstrate the use of this method.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1451-0
  • An efficient procedure for structural reliability-based robust design
    • Authors: Renato de S. Motta; Silvana M. B. Afonso
      Abstract: Abstract This paper focuses on the development of an optimization tool with the aim to obtain robust and reliable designs in short computational time. The robustness measures considered here are the expected value and standard deviation of the performance function involved in the optimization problem. When using these robustness measures combined, the search of optimal design appears as a robust multiobjective optimization (RMO) problem. Reliable design addresses uncertainties to restrict the structural probability of failure. The mathematical formulation for the reliability based robust design optimization (RBRDO) problem is obtained by adding a reliability based constraint into the RMO problem. As both, statistics calculations and the reliability analysis could be very costly, approximation technique based on reduced-order modeling (ROM) is also incorporated in our procedure. The selected ROM is the proper orthogonal decomposition (POD) method, with the aim to produce fast outputs considering structural non-linear behavior. Moreover, to obtain RBRDO designs with reduced CPU time we propose others developments to be added in the integrated tool. They are: Probabilistic Collocation Method (PCM) to evaluate the statistics of the structural responses and, also, an approximated reliability constraints procedure based on the Performance Measure Approach (PMA) for reliability constraint assessment. Finally, Normal-Boundary Intersection (NBI) or Normalized Normal-Constraint (NNC) multiobjective optimization techniques are employed to obtain fast and even spread Pareto robust designs. To illustrate the application of the proposed tool, optimization studies are conducted for a linear (benchmark) and nonlinear trusses problems. The nonlinear example consider different loads level, exploring the material plasticity. The integrated tool prove to be very effective reducing the computational time by up to five orders of magnitude, when compared to the solutions obtained via classical standard approaches.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1418-1
  • Representative surrogate problems as test functions for expensive
    • Authors: Ramses Sala; Niccolò Baldanzini; Marco Pierini
      Abstract: Abstract A large variety of algorithms for multidisciplinary optimization is available, but for various industrial problem types that involve expensive function evaluations, there is still few guidance available to select efficient optimization algorithms. This is also the case for multidisciplinary vehicle design optimization problems involving, e.g., weight, crashworthiness, and vibrational comfort responses. In this paper, an approach for the development of Representative Surrogate Problems (RSPs) as synthetic test functions for a relatively complex industrial problem is presented. The work builds on existing sensitivity analysis and surrogate data generation methods to establish a novel approach to generate surrogate function sets, which are accessible (i.e. not resource demanding) and aim to generate statistically representative instances of specific classes of industrial problems. The approach is demonstrated through the construction of RSPs for multidisciplinary optimization problems that occur in the context of structural car body design. As a “proof of concept” the RSP approach is applied for the selection of suitable optimization algorithms, for several problem formulations and for a meta-optimization (i.e. an optimization of the optimization algorithm parameters) to increase optimization efficiency. The potential of the approach is demonstrated by comparing the efficiency of several optimization algorithms on an RSP and an independent simulation-based vehicle model. The results corroborate the potential of the proposed approach and significant performance gains in optimization efficiency are achieved. Although the approach is developed for the particular application presented, the approach is described in a general way, to encourage readers to use the gist of the concept.
      PubDate: 2016-09-01
      DOI: 10.1007/s00158-016-1410-9
  • Topology optimization based on level set for a flexible multibody system
           modeled via ANCF
    • Authors: Jialiang Sun; Qiang Tian; Haiyan Hu
      Abstract: Abstract A topology optimization methodology is proposed for the flexible multibody system undergoing both large overall motion and large deformation. The system of concern is modeled via the absolute nodal coordinate formulation. The equivalent static load method is employed to transform the topology optimization of the nonlinear dynamic response of the system into a static one, and evaluated to adapt to the absolute nodal coordinate formulation by splitting the elastic deformations of the flexible components from the overall motions of those components. During the static topology optimization, the material interface is implicitly described as the zero level set of a higher-dimensional scalar function. Then, the semi-implicit level set method with the additive operator splitting algorithm is employed to solve the corresponding Hamilton-Jacobi partial differential equation. In addition, the expert evaluation method of weights based on the grey theory is utilized to define the objective function, and a modified augmented Lagrange multiplier method is proposed to treat the inequality volume constraint so as to avoid the oscillation and drift of the volume. Finally, two numerical examples are provided to validate the proposed methodology.
      PubDate: 2016-08-21
      DOI: 10.1007/s00158-016-1558-3
  • Grayscale-free topology optimization for electromagnetic design problem of
           in-vehicle reactor
    • Authors: Shintaro Yamasaki; Atsushi Kawamoto; Akira Saito; Masakatsu Kuroishi; Kikuo Fujita
      Abstract: Abstract In this paper, we propose grayscale-free topology optimization for a reactor design problem where the electromagnetic performance needs to be optimized. A reactor is an electric device to boost electric voltage, and is used as a part of a DC-DC converter in electric and hybrid vehicles. When designing reactors, we need to consider many performance indicators such as inductance and fringing loss. In general, high-performance reactor design that satisfies all requirements is not obvious, and topology optimization is promising for such non-trivial design problems. In this paper, we therefore establish a framework for the electromagnetic design of an in-vehicle reactor on the basis of boundary tracking type level-set topology optimization, which realizes grayscale-free topology optimization. Because of its grayscale-free characteristic, the established framework can completely resolve the numerical problems caused by the so-called grayscale elements. We present several numerical examples to demonstrate the usefulness of the established framework, and we discuss the possibilities for the expansion of the established framework to more difficult and valuable design problems.
      PubDate: 2016-08-19
      DOI: 10.1007/s00158-016-1557-4
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