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    - CHEMICAL ENGINEERING (186 journals)
    - CIVIL ENGINEERING (168 journals)
    - ELECTRICAL ENGINEERING (92 journals)
    - ENGINEERING (1176 journals)
    - HYDRAULIC ENGINEERING (56 journals)
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CIVIL ENGINEERING (168 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: 21)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 21)
Architectural Engineering     Open Access   (Followers: 5)
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: 5)
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: 10)
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: 5)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bioinspired Materials     Open Access  
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 15)
Building and Environment     Hybrid Journal   (Followers: 12)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 16)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 15)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 4)
Case Studies in Nondestructive Testing and Evaluation     Open Access  
Case Studies in Structural Engineering     Open Access  
Cement and Concrete Composites     Hybrid Journal   (Followers: 11)
Change Over Time     Full-text available via subscription   (Followers: 3)
Civil and Environmental Engineering     Open Access  
Civil And Environmental Engineering Reports     Open Access  
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: 103)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 9)
Computers & Structures     Hybrid Journal   (Followers: 26)
Concrete Research Letters     Open Access   (Followers: 2)
Constructii : Journal of Civil Engineering Research     Open Access   (Followers: 9)
Construction Engineering     Open Access   (Followers: 4)
Construction Management and Economics     Hybrid Journal   (Followers: 30)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access  
DFI Journal : The Journal of the Deep Foundations Institute     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   (Followers: 2)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 5)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 14)
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)
Hormigón y Acero     Full-text available via subscription  
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: 7)
International Journal of Condition Monitoring     Full-text available via subscription  
International Journal of Construction Engineering and Management     Open Access   (Followers: 6)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 1)
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: 3)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 10)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 2)
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 Bridge Engineering     Full-text available via subscription   (Followers: 18)
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: 3)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 12)
Journal of Civil Engineering Research     Open Access   (Followers: 12)
Journal of Civil Society     Hybrid Journal   (Followers: 3)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 3)
Journal of Composites     Open Access   (Followers: 39)

        1 2     

Journal Cover   Structural and Multidisciplinary Optimization
  [SJR: 1.825]   [H-I: 61]   [4 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  [2302 journals]
  • 3D level-set topology optimization: a machining feature-based approach
    • Abstract: Abstract This paper presents an explicit feature-based level-set topology optimization method involving polyline-arc profiling and 2.5D machining processes. This method relies on a feature fitting algorithm incorporated into the boundary evolvement process in order to regulate the noisy velocity fields and thus introduce new explicit feature primitives; once inserted, the feature-based shape optimization algorithm is implemented to determine the optimum part shape and topology. The research novelty lies in that, the best-fit feature primitives are inserted during the topology optimization process while other researchers so far have reported only manipulating some existing features with the conventional level-set methods. Therefore, feature-based design can be realized without special requirement of initial input or any post-processing. From the perspective of potential applications, the engineering information embedded in those feature primitives can be extracted and integrated into the optimization formulation. Such potential integration can make the topology optimization even more useful and practical. This effort is an extension of level-set topology optimization into a domain of structural optimization for manufacturing (OFM).
      PubDate: 2015-05-21
  • Weight and mechanical performance optimization of blended composite wing
           panels using lamination parameters
    • Abstract: Abstract In this paper, a lamination parameter-based approach to weight optimization of composite aircraft wing structures is addressed. It is a bi-level procedure where at the top level lamination parameters and numbers of plies of the pre-defined angles (0, 90, 45 and −45°) are used as design variables, the material volume is treated as an objective function to be minimized subject to the buckling, strength and ply percentage constraints. At the bottom level the optimum stacking sequence is obtained subject to the requirements on blending and preservation of mechanical properties. To ensure composite blending, a multi-stage optimization is performed by a permutation genetic algorithm aiming at matching the lamination parameters passed from the top level optimization as well as satisfying the layup rules. Two new additional criteria, the 90° ply angle jump index and the stack homogeneity index, are introduced to control the uniformity of the three ply angles (0, 90, 45 and −45) spread throughout the stack as well as improve the stack quality and mechanical performance by encouraging 45° angle change between neighbouring groups of plies. The results of the application of this approach are compared to published results to demonstrate the potential of the developed technique.
      PubDate: 2015-05-21
  • Topology and shape optimization methods using evolutionary algorithms: a
    • Abstract: Abstract Topology optimization has evolved rapidly since the late 1980s. The optimization of the geometry and topology of structures has a great impact on its performance, and the last two decades have seen an exponential increase in publications on structural optimization. This has mainly been due to the success of material distribution methods, originating in 1988, for generating optimal topologies of structural elements. Previous methods suffered from mathematical complexity and a limited scope for applicability, however with the advent of increased computational power and new techniques topology optimization has grown into a design tool used by industry. There are two main fields in structural topology optimization, gradient based, where mathematical models are derived to calculate the sensitivities of the design variables, and non gradient based, where material is removed or included using a sensitivity function. Both fields have been researched in great detail over the last two decades, to the point where structural topology optimization has been applied to real world structures. It is the objective of this review paper to present an overview of the developments in non gradient based structural topology and shape optimization, with a focus on evolutionary algorithms, which began as a non gradient method, but have developed to incorporate gradient based techniques. Starting with the early work and development of the popular algorithms and focusing on the various applications. The sensitivity functions for various optimization tasks are presented and real world applications are analyzed. The article concludes with new applications of topology optimization and applications in various engineering fields.
      PubDate: 2015-05-20
  • Benchmarking optimization solvers for structural topology optimization
    • Abstract: Abstract The purpose of this article is to benchmark different optimization solvers when applied to various finite element based structural topology optimization problems. An extensive and representative library of minimum compliance, minimum volume, and mechanism design problem instances for different sizes is developed for this benchmarking. The problems are based on a material interpolation scheme combined with a density filter. Different optimization solvers including Optimality Criteria (OC), the Method of Moving Asymptotes (MMA) and its globally convergent version GCMMA, the interior point solvers in IPOPT and FMINCON, and the sequential quadratic programming method in SNOPT, are benchmarked on the library using performance profiles. Whenever possible the methods are applied to both the nested and the Simultaneous Analysis and Design (SAND) formulations of the problem. The performance profiles conclude that general solvers are as efficient and reliable as classical structural topology optimization solvers. Moreover, the use of the exact Hessians in SAND formulations, generally produce designs with better objective function values. However, with the benchmarked implementations solving SAND formulations consumes more computational time than solving the corresponding nested formulations.
      PubDate: 2015-05-17
  • Analytical sensitivity in topology optimization for elastoplastic
    • Abstract: Abstract The present study proposes a topology optimization of composites considering elastoplastic deformation to maximize the energy absorption capacity of a structure under a prescribed material volume. The concept of a so-called multiphase material optimization, which is originally defined for a continuous damage model, is extended to elastoplastic composites with appropriate regularization for material properties in order to regularize material parameters between two constituents. In this study, we formulate the analytical sensitivity for topology optimization considering elastoplastic deformationand its path-dependency. For optimization applying a gradient-based method, the accuracy of sensitivities iscritical to obtain a reliable optimization result. The proposed analytical sensitivity method takes the derivative of the total stress which satisfies equilibrium equation instead of that of the incremental stress and does not need implicit sensitivity terms. It is verified that the proposed method can provide highly accurate sensitivity enough to obtain reliable optimization results by comparing with that evaluated from the finite difference approach.
      PubDate: 2015-05-15
  • Predictive quantification of surrogate model fidelity based on modal
           variations with sample density
    • Abstract: Abstract It is generally challenging to quantify the fidelity of surrogate models without additional system evaluations. Standard error measures, such as the mean squared error and cross-validation error, often do not adequately capture the fidelity of the model trained using all available sample points. This paper introduces a new model-independent approach to quantify surrogate model fidelity, called Predictive Estimation of Model Fidelity (PEMF). In PEMF, intermediate surrogates are iteratively constructed over heuristic subsets of sample points. The median and the maximum errors estimated over the remaining points are used to determine the respective error distributions at each iteration. The estimated modes of the error distributions are represented as functions of the density of intermediate training points through nonlinear regression, assuming a smooth decreasing trend of errors with increasing sample density. These regression functions are then used to predict the expected median and maximum errors in the final surrogate model (trained using all available sample points). A Monotonic Trend criterion is defined to statistically test if the regression function is reasonably reliable in predicting the model fidelity, failing which a stable implementation of k-fold cross-validation (based on modal error) is used to predict the final surrogate error. To compare the accuracy and robustness of PEMF with that of the popular leave-one-out cross-validation, numerical experiments are performed using Kriging, RBF, and E-RBF models. It is observed that the model fidelities estimated by PEMF is up to two orders of magnitude more accurate and statistically more stable compared to those based on cross-validation.
      PubDate: 2015-05-14
  • New optimization method for steered fiber composites using the level set
    • Abstract: Abstract Advanced fiber placement (AFP) composite manufacturing technology offers a means to tailor composite fibers for complex loading environments and significantly improve the overall structural efficiency. This paper introduces a new method to optimize the continuously varying fiber paths for AFP using a level set method. The paths of the fibers are defined by constant level set function values, describing a series of continuous equally spaced fiber paths. The sensitivity of the structural compliance to a change in level set function definition of the fiber path is derived. The sensitivities are used to optimize the level set defined fiber paths to minimize structural compliance, while maintaining the continuous fiber paths and producing a solution that can be manufactured using AFP. The optimization method is demonstrated in three numerical studies.
      PubDate: 2015-05-14
  • A two-stage stochastic PDE-constrained optimization approach to vibration
           control of an electrically conductive composite plate subjected to
           mechanical and electromagnetic loads
    • Abstract: Abstract A new two-stage stochastic partial differential equation (PDE)-constrained optimization methodology is developed for the active vibration control of structures in the presence of uncertainties in mechanical loads. The methodology relies on the two-stage stochastic optimization formulation with an embedded first-order black-box PDE-constrained optimization procedure. The PDE-constrained optimization procedure utilizes a first-order active-set algorithm with a conjugate gradient method. The objective function is determined through solution of the governing PDEs and its gradient is computed using automatic differentiation with hyper-dual numbers. The developed optimization methodology is applied to the problem of post-impact vibration control (via applied electromagnetic field) of an electrically conductive carbon fiber reinforced composite plate subjected to an uncertain, or stochastic, impact load. The corresponding governing PDEs consist of a nonlinear coupled system of equations of motion and Maxwell’s equations. The conducted computational study shows that the obtained two-stage optimization solution allows for a significant suppression of vibrations caused by the randomized impact load in all impact load scenarios. Also, the effectiveness of the developed methodology is illustrated in the case of a deterministic impact load, where the two-stage strategy enables one to practically eliminate post-impact vibrations.
      PubDate: 2015-05-13
  • Efficient global robust optimization of unconstrained problems affected by
           parametric uncertainties
    • Abstract: Abstract A novel technique for efficient global robust optimization of problems affected by parametric uncertainties is proposed. The method is especially relevant to problems that are based on expensive computer simulations. The globally robust optimal design is obtained by searching for the best worst-case cost, which involves a nested min-max optimization problem. In order to reduce the number of expensive function evaluations, we fit response surfaces using Kriging and use adapted versions of expected improvement to direct the search for the robust optimum. The numerical performance of the algorithm is compared against other techniques for min-max optimization on established test problems. The proposed approach exhibits reliable convergence, is more efficient than previous methods and shows strong scalability.
      PubDate: 2015-05-13
  • Sensitivity analysis and optimization of eigenmode localization in
           continuum systems
    • Abstract: Abstract A model problem arising from optical design of photonic bandgap structure is investigated. That is, the optimization problem is to find the material inhomogeneity in a domain so that a particular eigenmode governed by the scalar Helmholtz equation is localized. The continuum sensitivity analysis of the objective function including the eigenmode is carried out. The derivative of the objective function with respect to the density function is obtained by the sensitivity problem and the adjoint problem in continuum systems. When the multiplicity of eigenmode happens, our strategy is to select the closest eigenmode to the current eigenmode. Four numerical examples in a square domain are studied, with different weight functions and initial density distributions. The numerical results illustrate the validity of the algorithm based on the continuum sensitivity analysis.
      PubDate: 2015-05-08
  • Torque control strategy and optimization for fuel consumption and emission
           reduction in parallel hybrid electric vehicles
    • Abstract: Abstract To reduce fuel consumption and exhaust emissions in hybrid electric vehicles (HEVs), it is important to develop a well-organized energy management system (EMS). This paper proposes a torque control strategy coupled with optimization for a parallel HEV. A torque control strategy is developed first. In particular, a function to control the driving condition, called the internal combustion engine (ICE) torque control function, is introduced. This function controls the driving conditions (electric motor (EM) driving, ICE driving, and ICE driving assisted by EM) for reducing fuel consumption and exhaust emissions. This function depends on several design variables that should be optimized. Numerical simulation of HEV using Matlab/Simulink is so computationally intensive that a sequential approximate optimization (SAO) using a radial basis function network (RBF) is adopted to determine the optimal values of these design variables. As the result, the optimal ICE torque control function is determined with a small number of simulation runs. In this paper, CO2 and NOx emissions are minimized simultaneously for reducing the fuel consumption and exhaust emission. Through numerical simulations using typical driving cycles, the trade-off between CO2 and NOx emissions is clarified and the validity of the proposed torque control strategy coupled with the proposed optimization is examined.
      PubDate: 2015-05-04
  • A comparison between robust and risk-based optimization under uncertainty
    • Abstract: Abstract Robust optimization aims at producing designs which are less sensitive to uncertainties. Risk optimization looks for designs with optimal balance between performance and safety. In spite of the different objectives, robust and risk-based formulations have strong similitude, which has not been thoroughly explored before. This paper explores the similarities and differences between these formulations. It is shown that the alpha factors, which are employed in compromise solutions in robust optimization, are equivalent to the costs of failure in risk-based optimization. Moreover, it is shown that the robust objective function is often non-convex, with results being given by (often arbitrary) design constraints. In some sense, the robust objective function lacks objectiveness, with results largely dependent on arbitrary normalizing constants. On the other hand, when there is a critical limit to performance, which characterizes system failure, and when costs of failure can be defined, the risk-based optimization yields consistent results, and no normalizing constants are needed.
      PubDate: 2015-05-02
  • Structural mass reduction by integrating active material in direct drive
           generator design
    • Abstract: Abstract Permanent magnet synchronous generator technology is known for its low power to mass ratio. Its heavy structural design results from the need to ensure a small air-gap at a large diameter between stator and rotor parts. Numerous options for lowering structural mass are considered. In this paper, an overall mass reduction strategy which entails the integration of the magnetically active parts with the support structure are presented. Two three megawatt generator designs, one with a single bearing and the other with double bearing lay-up, are considered. These models comprise three-dimensional elements, isotropic and orthotropic materials, linear static extreme hub loads, and magnetic stresses. Shape and size optimisations are applied in calculation of structural mass saving incurred from structural integration and the altering of rotor and stator yoke thicknesses. The results show that total generator mass reduction is possible through the integration of the active material.
      PubDate: 2015-04-26
  • Probability of failure sensitivity with respect to decision variables
    • Abstract: Abstract This note introduces a derivation of the sensitivities of a probability of failure with respect to decision variables. For instance, the gradient of the probability of failure with respect to deterministic design variables might be needed in RBDO. These sensitivities might also be useful for Uncertainty-based Multidisciplinary Design Optimization. The difficulty stems from the dependence of the failure domain on variations of the decision variables. This dependence leads to a derivative of the indicator function in the form of a Dirac distribution in the expression of the sensitivities. Based on an approximation of the Dirac, an estimator of the sensitivities is analytically derived in the case of Crude Monte Carlo first and Subset Simulation. The choice of the Dirac approximation is discussed.
      PubDate: 2015-04-25
  • Optimum design of FRP bridge deck: an efficient RS-HDMR based approach
    • Abstract: Abstract A novel efficient hybrid method based on random sampling-high dimensional model representations (RS-HDMR) and genetic algorithm coupled with a local unconstrained multivariable minimization function is proposed in this study for optimization of FRP composite web core bridge deck panels. The optimization is performed for lightweight design of FRP composite bridge deck panels based on deflection limit, stresses, buckling and failure criteria and subsequently the representative design curves are developed considering normal as well as skew configurations of FRP bridge decks. Sensitivity analysis is also performed to study the effect of variation in geometry of the bridge deck to its deflection, stress and buckling behaviours. High level of computational efficiency can be achieved without compromising the accuracy of results for optimization of high dimensional systems following the proposed approach.
      PubDate: 2015-04-25
  • On the layout of a least weight multiple span structure with uniform load
    • Abstract: Abstract This paper focuses on identifying an analytical description for the layout of a minimum volume pin-jointed structure (truss) that is uniformly loaded and supported on equally spaced locations. The methodology utilized takes advantage of Maxwell’s Theorem of Load Paths and the properties of reciprocal diagrams (as described by the authors in previous papers). The approach followed in this work provides considerable insight in the properties of the optimal layout. In addition, the solution to the problem is presented in terms of a structure and its dual. The dual truss associated with the force diagram of the original structure has the same total load path as the original structure itself but completely different geometry and corresponds to a different, but related, load condition. Therefore, multiple optimal layouts are available to the practicing engineer for the problem considered. Analytical expressions describing the geometry and the volume of the optimal truss layout and its dual are provided showing that simple formulas describe the geometric properties of the solution. The solutions are presented for equal magnitude tensile and compressive stress limits first and then the effect of unequal stress limits is explored. Comparison with numerical results confirms the validity of the solutions presented.
      PubDate: 2015-04-24
  • Optimization of structures with unrestricted dynamic shakedown constraints
    • Abstract: Abstract The unrestricted dynamic shakedown theory is here utilized with the aim to formulate different optimal design problems for structures mainly subjected to seismic loads. In particular, reference is made to plane frame structures constituted by elastic perfectly plastic material subjected to load combinations characterized by the presence of simultaneous fixed and seismic actions. The design problems, formulated on the ground of a statical approach, are devoted to structures with and without seismic protection devices, with special emphasis to seismic isolators. For the proposed design problem formulations different constraints are utilized; actually, for structures without protection devices the design problem must impose that the optimal structure remains elastic for fixed loads, shakes down for serviceability seismic conditions and prevents the instantaneous collapse for high seismic loads; while for structures provided with a given base isolation system, it is imposed that they remain elastic for fixed loads and shakes down for full seismic conditions. Appropriate modal analyses are utilized in order to take into account for both classically and non-classically damped structures. The seismic load history to be considered for shakedown and collapse limit admissibility conditions is a repeated seismic load one according with the unrestricted shakedown theory. The effected applications are related to plane steel frames.
      PubDate: 2015-04-23
  • A variational growth approach to topology optimization
    • Abstract: Abstract This paper presents a new approach to topology optimization that is based on observations of natural biological systems in which growth processes are initialized during high mechanical loading. A compliance parameter is introduced that serves as an internal variable and for which evolution equations are derived using the variational principle of the minimum of the dissipation potential. The well-known problem of checkerboarding is faced with regularization techniques on the Helmholtz free energy. The final procedure uses only the Helmholtz free energy as input. Several numerical examples are given for demonstration purposes.
      PubDate: 2015-04-17
  • Design optimization based on state problem functionals
    • Abstract: Abstract This paper presents a general mathematical structure for design optimization problems, where state problem functionals are used as design objectives.It extends to design optimization the general model of physical theories pioneered by Tonti (1972, 1976) and Oden and Reddy (1974, 1983). It turns out that the classical structural optimization problem of compliance minimization is a member of the treated general class of problems. Other particular examples, discussed in the paper, are related to Darcy-Stokes flow and pipe flow models. A main novel feature of the paper is the unification of seemingly different design problems, but the general mathematical structure also explains some previously not fully understood phenomena. For instance, the self-penalization property of Stokes flow design optimization receives an explanation in terms of minimization of a concave function over a convex set.
      PubDate: 2015-04-16
  • Discrete sizing optimization of steel trusses under multiple displacement
           constraints and load cases using guided stochastic search technique
    • Abstract: Abstract The guided stochastic search (GSS) is a computationally efficient design optimization technique, which is originally developed for discrete sizing optimization problems of steel trusses with a single displacement constraint under a single load case. The present study aims to investigate the GSS in a more general class of truss sizing optimization problems subject to multiple displacement constraints and load cases. To this end, enhancements of the GSS are proposed in the form of two alternative approaches that enable the technique to deal with multiple displacement/load cases. The first approach implements a methodology in which the most critical displacement direction is considered only when guiding the search process. The second approach, however, takes into account the cumulative effect of all the critical displacement directions in the course of optimization. Advantage of the integrated force method of structural analysis is also utilized for further reduction of the computational effort in these approaches. The proposed enhancements of GSS are investigated and compared with some selected techniques of design optimization through six truss structures that are sized for minimum weight. The numerical results reveal that both enhancements generally provide promising solutions with an insignificant computational effort.
      PubDate: 2015-04-15
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