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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: 1)
Advances in Civil Engineering     Open Access   (Followers: 25)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 14)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 18)
Architectural Engineering     Open Access   (Followers: 4)
Archives of Civil Engineering     Open Access   (Followers: 5)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access  
ATBU Journal of Environmental Technology     Open Access   (Followers: 1)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 3)
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: 12)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 14)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 2)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 9)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 5)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 3)
Case Studies in Structural Engineering     Open Access   (Followers: 1)
Cement and Concrete Composites     Hybrid Journal   (Followers: 13)
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: 4)
Civil And Environmental Engineering Reports     Open Access   (Followers: 2)
Civil and Environmental Research     Open Access   (Followers: 14)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 3)
Civil Engineering and Architecture     Open Access   (Followers: 5)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 2)
Civil Engineering and Technology     Open Access   (Followers: 4)
Civil Engineering Dimension     Open Access   (Followers: 5)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 195)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 8)
Computers & Structures     Hybrid Journal   (Followers: 25)
Concrete Research Letters     Open Access   (Followers: 2)
Construction Economics and Building     Open Access   (Followers: 1)
Construction Engineering     Open Access   (Followers: 5)
Construction Management and Economics     Hybrid Journal   (Followers: 18)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 1)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal  
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 12)
Enfoque UTE     Open Access   (Followers: 1)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 5)
Engineering Structures     Hybrid Journal   (Followers: 11)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 1)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 12)
Environmental Geotechnics     Open Access   (Followers: 3)
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  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 3)
Geomaterials     Open Access   (Followers: 1)
Geosystem Engineering     Hybrid Journal  
Geotechnik     Hybrid Journal   (Followers: 1)
Géotechnique Letters     Hybrid Journal   (Followers: 3)
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)
Ingenio Magno     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 15)
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: 6)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 6)
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: 1)
International Journal of Masonry Research and Innovation     Hybrid Journal  
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: 6)
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: 3)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 7)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 2)
Journal of Accessibility and Design for All     Open Access   (Followers: 6)
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  
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 5)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Science     Open Access   (Followers: 7)
Journal of Civil Engineering Research     Open Access   (Followers: 5)
Journal of Civil Society     Hybrid Journal   (Followers: 3)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 3)
Journal of Composites     Open Access   (Followers: 68)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 12)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 20)
Journal of Construction Engineering     Open Access   (Followers: 4)
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: 1)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 4)
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: 8)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 15)
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: 2)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 7)
Journal of Offshore Structure and Technology     Full-text available via subscription  
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 3)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 6)
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: 32)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 5)
Journal of Structures     Open Access   (Followers: 2)
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: 11)
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 3)
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: 10)
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: 5)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 2)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 54)
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  
Steel Construction - Design and Research     Hybrid Journal   (Followers: 1)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 7)
Structural Concrete     Hybrid Journal   (Followers: 9)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 6)
Structural Engineering International     Full-text available via subscription   (Followers: 8)
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: 5)
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: 4)
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: 1)
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: 6)
Water Science & Technology     Partially Free   (Followers: 18)
Water Science and Technology : Water Supply     Partially Free   (Followers: 20)


Journal Cover Structural and Multidisciplinary Optimization
  [SJR: 1.825]   [H-I: 61]   [7 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  [2281 journals]
  • A level-set method for steady-state and transient natural convection
    • Abstract: This paper introduces a topology optimization method for 2D and 3D, steady-state and transient heat transfer problems that are dominated by natural convection in the fluid phase and diffusion in the solid phase. The geometry of the fluid-solid interface is described by an explicit level set method which allows for both shape and topological changes in the optimization process. The heat transfer in the fluid is modeled by an advection-diffusion equation. The fluid velocity is described by the incompressible Navier-Stokes equations augmented by a Boussinesq approximation of the buoyancy forces. The temperature field in the solid is predicted by a linear diffusion model. The governing equations in both the fluid and solid phases are discretized in space by a generalized formulation of the extended finite element method which preserves the crisp geometry definition of the level set method. The interface conditions at the fluid-solid boundary are enforced by Nitsche’s method. The proposed method is studied for problems optimizing the geometry of cooling devices. The numerical results demonstrate the applicability of the proposed method for a wide spectrum of problems. As the flow may exhibit dynamic instabilities, transient phenomena need to be considered when optimizing the geometry. However, the computational burden increases significantly when the time evolution of the flow fields needs to be resolved.
      PubDate: 2016-05-01
  • Damage approach: A new method for topology optimization with local stress
    • Abstract: In this paper, we propose a new method for topology optimization with local stress constraints. In this method, material in which a stress constraint is violated is considered as damaged. Since damaged material will contribute less to the overall performance of the structure, the optimizer will promote a design with a minimal amount of damaged material. We tested the method on several benchmark problems, and the results show that the method is a viable alternative for conventional stress-based approaches based on constraint relaxation followed by constraint aggregation.
      PubDate: 2016-05-01
  • A reliability index extrapolation method for separable limit states
    • Abstract: When the limit state function (or performance function) of a structure can be written as the difference of a capacity function and a response function that are expressed in terms of independent sets of random variables (i.e., when the limit state function has a separable form), efficient simulation based techniques (e.g., Separable Monte Carlo Simulation method) can be used to predict the reliability of the structure. The accuracies of these simulation based techniques, on the other hand, diminishes as the structural reliability increases. This paper proposes a reliability index extrapolation method to predict reliability of a highly safe structure that has a separable limit state function. In this method, the standard deviations of the random variables that contribute to the capacity function are artificially inflated by using a scale parameter to obtain various (smaller) scaled reliability index values (that can be predicted accurately with small number of samples). The standard deviations of the random variables that contribute to the response function are kept unchanged in order to use the same response values in prediction of various scaled reliability indices. Then, least square regression is used to build a relationship between the standard deviation scale parameter and scaled reliability index values. Finally, an extrapolation is performed to estimate the actual (higher) reliability index. The accuracy of the proposed method is evaluated through reliability assessment of mathematical and structural mechanics example problems as well as a reliability based design optimization problem. It is found that the proposed method can provide reasonable accuracy for high reliability index estimations with only 1000 response function evaluations.
      PubDate: 2016-05-01
  • Level set topology optimization of cooling and heating devices using a
           simplified convection model
    • Abstract: This paper studies topology optimization of convective heat transfer problems in two and three dimensions. The convective fluxes are approximated by Newton’s Law of Cooling (NLC). The geometry is described by a Level Set Method (LSM) and the temperature field is predicted by the eXtended Finite Element Method (XFEM). A constraint on the spatial gradient of the level set field is introduced to penalize small, sub-element-size geometric features. Numerical studies show that the LSM-XFEM provides improved accuracy over previously studied density methods and LSMs using Ersatz material models. It is shown that the NLC model with an iso-thermal fluid phase may over predict the convective heat flux and thus promote the formation of very thin fluid channels, depending on the Biot number characterizing the heat transfer problem. Approximating the temperature field in the fluid phase by a diffusive model mitigates this issue but an explicit feature size control is still necessary to prevent the formation of small solid members, in particular at low Biot numbers. The proposed constraint on the gradient of the level set field is shown to suppress sub-element-size features but necessitates a continuation strategy to prevent the optimization process from stagnating as geometric features merge.
      PubDate: 2016-05-01
  • Symmetry analysis for structural optimization problems involving
           reliability measure and bi-modulus materials
    • Abstract: In the present work, some symmetry theorems for structural optimization problems involving reliability measure and bi-modulus materials are established. In the first part of this paper, two types of symmetric reliability-based structural optimization problems are discussed. It is proved that, for the first type symmetric RBDO problems, the existence of symmetric global optimal solutions can be guaranteed even through the probability density function (PDF) is non-symmetric. While for the second type symmetric RBDO problems, more severe conditions on PDF are required to ensure the existence of symmetric global optimal solutions. In the second part of the paper, the convexity of the compliance of truss structures involving bi-modulus materials is confirmed firstly. Based on this result, it is found that for both deterministic and robust symmetric compliance minimization of truss structures involving bi-modulus materials, symmetric global optima always exist. The theoretical results are also demonstrated through some academic examples.
      PubDate: 2016-05-01
  • Ensemble of metamodels: the augmented least squares approach
    • Abstract: In this work we present an approach to create ensemble of metamodels (or weighted averaged surrogates) based on least squares (LS) approximation. The LS approach is appealing since it is possible to estimate the ensemble weights without using any explicit error metrics as in most of the existent ensemble methods. As an additional feature, the LS based ensemble of metamodels has a prediction variance function that enables the extension to the efficient global optimization. The proposed LS approach is a variation of the standard LS regression by augmenting the matrices in such a way that minimizes the effects of multicollinearity inherent to calculation of the ensemble weights. We tested and compared the augmented LS approach with different LS variants and also with existent ensemble methods, by means of analytical and real-world functions from two to forty-four variables. The augmented least squares approach performed with good accuracy and stability for prediction purposes, in the same level of other ensemble methods and has computational cost comparable to the faster ones.
      PubDate: 2016-05-01
  • Multidisciplinary design and optimization of the twin-web turbine disk
    • Abstract: The newly designed structures are employed to improve the high pressure turbine (HPT) disk to the expected performance. The twin-web disk (TWD) has been proven to be the future trend of the HPT disk due to its breakthrough in weight loss, strength and heat transfer efficiency compared to the conventional single web disk (SWD). Because of the multi-physics working conditions and intense coupling of multiple disciplines, the conventional design of the HPT disk is a labor intensive work. A series of design procedures, including asymmetrical computational fluid dynamics (CFD) analysis, inverse distance weighted (IDW) interpolation method, multidisciplinary feasible method (MDF), and design of experiments (DOE), are proposed to obtain the proper design for both TWD and SWD in an efficient way. In the present work, the multidisciplinary design of optimization (MDO) has been performed to find the proper shape of the TWD disk with the minimum mass. The results showed that the TWD exhibits a better performance in heat transfer and weight loss than SWD. The modeling and optimization procedure of this work can be referred for engineering design.
      PubDate: 2016-05-01
  • Reliability based optimization in aeroelastic stability problems using
           polynomial chaos based metamodels
    • Abstract: In this work, reliability based design optimization (RBDO) of two aeroelastic stability problems is addressed: (i) divergence, which arises in static aeroelasticity, and (ii) flutter, which arises in dynamic aeroelasticity. A set of design variables is considered as random variables, and the mean mass is minimized for a given set of constraints — including the probability of failure by divergence or flutter. The optimization process requires repeated evaluation of reliability, which is a major contributor to the total computational cost. To reduce this cost, a polynomial chaos expansion (PCE)-based metamodel is created over a grid in the parameter space. These precomputed PCEs are then interpolated for reliability calculation at intermediate points in the parameter space, as demanded by the optimization algorithm. Two new modifications are made to this method in this work. First, the Gauss quadrature rule is used — instead of statistical simulation — to estimate the chaos coefficients for higher computational speed. Second, to increase this computational gain further, a non-uniform grid is chosen instead of a uniform one, based on relative importance of the design parameters. This relative importance is found from a global sensitivity analysis. This new modified method is applied on a rectangular unswept cantilever wing model. For both optimization problems, it is observed that the proposed method yields accurate results with a considerable computational cost reduction, when compared to simulation based methods. The effect of grid spacing is also explored to achieve the best computational efficiency.
      PubDate: 2016-05-01
  • Improving kriging surrogates of high-dimensional design models by Partial
           Least Squares dimension reduction
    • Abstract: Engineering computer codes are often computationally expensive. To lighten this load, we exploit new covariance kernels to replace computationally expensive codes with surrogate models. For input spaces with large dimensions, using the kriging model in the standard way is computationally expensive because a large covariance matrix must be inverted several times to estimate the parameters of the model. We address this issue herein by constructing a covariance kernel that depends on only a few parameters. The new kernel is constructed based on information obtained from the Partial Least Squares method. Promising results are obtained for numerical examples with up to 100 dimensions, and significant computational gain is obtained while maintaining sufficient accuracy.
      PubDate: 2016-05-01
  • High fidelity multidisciplinary design optimisation of an electromagnetic
    • Abstract: The application of multidisciplinary design optimisation is mostly confined to bi-disciplinary systems such as fluid-structure interaction problems. High fidelity models of three disciplines involving electromagnetic-thermal-structural designs are rare. Here, the multidisciplinary optimisation of such a design is presented. The device comprises a C-shaped iron core and a single coil. The problem is decomposed using a monolithic multidisciplinary feasible architecture. The multidisciplinary analyses involve a single three-dimensional finite element mesh for transient non-linear electromagnetic, non-linear-static thermal, and linear-static structural models. During each multidisciplinary iteration the mesh is linearly morphed. A gradient based optimisation algorithm in combination with a multi-start routine is applied to the constrained mass minimisation problem. Multidisciplinary feasibility is ensured by convergence of a single coupling parameter i.e. air-gap deformation. In conclusion, some multidisciplinary optimisation, analyses, and decomposition considerations are discussed.
      PubDate: 2016-05-01
  • Effects of interfacial conditions on shape optimization of cementless hip
           stem: an investigation based on a hybrid framework
    • Abstract: The typical biomechanical failure mechanisms associated with cementless Total Hip Arthroplasty (THA) are initial micromotion, stress shielding and interface stresses. While the former is a short-term load-induced failure criterion affiliated with the post-surgery rehabilitation period, the other two mechanisms are relatively longer term phenomena. At immediate post-operative stage, biologic fixation through bone ingrowth is yet to occur and implant stability is determined by the initial micromotion. However, by the time the other failure mechanisms become prominent, sufficient bone ingrowth already prevails and consequently, the implant-bone interface characteristic changes. Therefore, any preclinical simulation aimed at designing femoral implants needs to account for this dual interfacial behaviour while dealing with these failure objectives. The present study implements a hybrid framework comprised of neural network (NN), genetic algorithm (GA) and finite element (FE) analysis for a multi-criteria 3-D shape optimization of cementless femoral implant by addressing the dual interfacial behaviour. Bonded interfacial condition was used to analyse the effects of stress shielding and interface stresses, whereas a set of contact models were used to develop an NN for faster prediction of the initial micromotion based on implant geometry. The final trade-off implant models were analysed and subsequently, compared with a generic design of femoral implant.
      PubDate: 2016-05-01
  • Multiplicity of the maximum eigenvalue in structural optimization problems
    • Abstract: Many problems in structural optimization can be formulated as a minimization of the maximum eigenvalue of a symmetric matrix. In practise it is often observed that the maximum eigenvalue has multiplicity greater than one close to or at optimal solutions. In this note we give a sufficient condition for this to happen at extreme points in the optimal solution set. If, as in topology optimization, each design variable determines the amount of material in a finite element in the design domain then this condition essentially amounts to saying that the number of elements containing material at a solution must be greater than the order of the matrix.
      PubDate: 2016-05-01
  • Structural topology optimization with design-dependent pressure loads
    • Abstract: One way to solve topology optimization of continuum structures under design-dependent pressure loads is to recover the loading surface at each step of the minimization process. During the topology evolution, the intermediate topologies obtained by using the SIMP (Solid Isotropic Material with Penalization) method actually can be regarded as gray scale images, for which the paper proposes a new material boundary identification scheme based on image segmentation technique. The Distance Regularized Level Set Evolution (DRLSE) method proposed by Li et al., IEEE Trans Image Process 19(12):3243–3254 (2010) is utilized to detect the image edge. Then the pressure boundary is represented as the zero level contour of a level set function (LSF). Inheriting the merits of the level set method, the current scheme can handle the topological change of the pressure boundary efficiently and be easily extended to the three-dimensional problems. In addition, the scheme is more stable compared with the conventional loading surface searching methods since it works well for the intermediate topologies with local scattered densities. A new optimization framework is also proposed to avoid the load sensitivity analysis. Four numerical examples are presented to show the validity and advantages of the proposed scheme.
      PubDate: 2016-05-01
  • Sensitivity reanalysis of static displacement using Taylor series
           expansion and combined approximate method
    • Abstract: This paper presents a new sensitivity reanalysis of static displacement for arbitrary changes of design variables. The current displacement of modified sensitivity equations is approximately calculated by using Taylor series expansion and then the direct sensitivity equations are solved by combined approximate method. Two types of numerical examples, including size sensitivity and shape sensitivity, are used to verify the accuracy and efficiency of the proposed method, which is more efficient than the existed methods. Although the Kirsch and Papalambros reanalysis method is more accurate, the proposed method can also acquire the accurate solution for the case of large modification. Therefore, this new method will have great potential application in the gradient-based structural optimization.
      PubDate: 2016-05-01
  • Topology optimization of metal nanostructures for localized surface
           plasmon resonances
    • Abstract: This note presents an inverse design methodology of metal nanostructures for localized surface plasmon resonances, based on the topology optimization approach. Using the proposed method, determination of the metal distribution in nanostructures is implemented for surface enhanced Raman spectroscopy to maximize the enhancement factor. The obtained results demonstrate that the outlined approach can be used to design metal nanostructure with resonant peak and significant enhancement factor at specified incident wavelength, and to control the shift of the resonant peak by topologically optimizing the nanostructure.
      PubDate: 2016-05-01
  • Solving stress and compliance constrained volume minimization using
           anisotropic mesh adaptation, the method of moving asymptotes and a global
    • Abstract: The p-norm often used in stress constrained topology optimisation supposedly mimics a delta function and it is thus characterised by a small length scale and ideally one would also prefer to have the solid-void transition occur over a small length scale, since the material in this transition does not have a clear physical interpretation. We propose to resolve these small length scales using anisotropic mesh adaptation. We use the method of moving asymptotes with interpolation of sensitivities, asymptotes and design variables between iterations. We demonstrate this combination for the portal and L-bracket problems with p=10, and we are able to investigate mesh dependence. Finally, we suggest relaxing the L-bracket problem statement by introducing a rounded corner.
      PubDate: 2016-04-28
  • Topological design for mechanical metamaterials using a multiphase level
           set method
    • Abstract: Metamaterials usually refer to artificially engineered composites with unusual properties that cannot be easily found in nature. This paper will develop a topological shape optimization method for design of mechanical metamaterials of thermoelastic micro-structured composites, which integrates numerical homogenization method with a multi-phase level set method (MPLSM). The homogenization method is applied to evaluate the effective macroscopic properties of a periodic microstructure, while the MPLSM will be utilized to implement shape and topology evolutions of the microstructure. A multi-phase level set representation model is established to describe the boundaries of the multi-material microstructure using a combination of all level set functions, without overlaps and empties. The Hamilton-Jacobi partial differential equation-based topological shape optimization problem will be transformed to a generalized size optimization problem. Typical numerical examples are used to demonstrate the effectiveness of the proposed method for designing metamaterials with expected and extreme thermal expansion coefficients.
      PubDate: 2016-04-28
  • Cost optimization of structures using a genetic algorithm with Eugenic
           Evolutionary theory
    • Abstract: This paper illustrates the cost optimization of steel frame structures by mean of genetic algorithm developed from the Eugenics Evolutionary theory. The aim is to obtain a final structure with a minimum cost. To this end, a modified multiple objective function has been defined. This considers cost as the result of a summary where elements like welds, simple connections, or the number of structural elements, have an influence on the final result. According to the Eugenics Evolutionary theory, a new selection operator has been developed in a way that leads to all members of the population being able to have descendants and avoids the loss of any kind of genetic material. In addition, the penalization coefficients have been optimised and the effect of parameter setting has been investigated, to achieve convergence faster through penalising the most expensive structures and looking for the optimum range of parameters’ value. The result is a robust genetic algorithm which, compared with others, achieves better optimum individuals and does not stop at local minima. Finally, two different two-dimensional truss frames have been optimized and the results have been compared with those obtained using different methods of selection like elitism, steady-state replacement, roulette wheel, and tournament selection.
      PubDate: 2016-04-28
  • Seismic layout optimization of steel braced frames by an improved dolphin
           echolocation algorithm
    • Abstract: The present paper tackles the problem of seismic performance-based layout optimization of steel braced frames subject to earthquake loading. Design variables of the optimization problem include the cross-sections of beams, columns, X-bracings and the placement of the bracings in the frame. To check the ultimate limit-state constraints during the optimization process, the structural responses are computed at the performance levels by conducting nonlinear static pushover analysis. In order to implement the optimization task an improved dolphin echolocation meta-heuristic algorithm is proposed. In dolphin echolocation algorithm, the echolocation behavior of dolphins is simulated to search the design space of the optimization problem. To illustrate the efficiency of the proposed methodology, five numerical examples are presented. The numerical results demonstrate the superiority of the proposed meta-heuristic over its standard version. Furthermore, it is observed that the performance-based layout optimization process finds structural configurations which are about 10 % lighter than those of obtained by the pure sizing optimization.
      PubDate: 2016-04-28
  • Multidisciplinary design optimization of tunnel boring machine considering
    • Abstract: A Tunnel Boring Machine (TBM) is an extremely large and complex engineering machine that usually works under a complicated geological environment to excavate tunnel underground. Considering the large number of sub-systems that usually belong to different disciplines, it is a challenging task to define, model, and optimize the whole TBM from the perspective of system engineering. Also, due to the complex mechanism and geological environment, the flexibility and efficiency of existing TBM excavation strategies are generally limited. To address these challenges, a multidisciplinary modeling is presented so that corresponding analytical or empirical models of each sub-system are formulated, and a multidisciplinary design optimization (MDO) method is applied to the TBM system optimization. Four excavation strategies are studied and compared, including: (i) two existing excavation strategies, and (ii) two new proposed excavation strategies by making control and/or structure parameters adaptive to geological conditions. Two case studies with these four excavation strategies are presented to illustrate the effectiveness and benefits of designing TBM using MDO methodologies. Wherein, Case I aims to minimize the construction period taking into account the restriction of sub-systems, and Case II simultaneously minimizes construction period, cost, and energy consumption. Since the resulting MDO formulation is straightforward to be solved as a single problem, the All-At-Once (AAO) method is utilized in this paper. The optimization results obtained by modeling the problem as MDO show that the excavation strategy with adaptive control and structure parameters can significantly reduce the total construction time, with lower cost and energy consumption.
      PubDate: 2016-04-28
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