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  Subjects -> ENGINEERING (Total: 1961 journals)
    - CHEMICAL ENGINEERING (153 journals)
    - CIVIL ENGINEERING (149 journals)
    - ELECTRICAL ENGINEERING (81 journals)
    - ENGINEERING (1114 journals)
    - HYDRAULIC ENGINEERING (46 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CIVIL ENGINEERING (149 journals)                  1 2     

ACI Structural Journal     Full-text available via subscription   (Followers: 6)
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: 24)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 19)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 16)
Architectural Engineering     Open Access   (Followers: 3)
Archives of Civil Engineering     Open Access   (Followers: 7)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access  
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 3)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription  
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 8)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 5)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 12)
Building and Environment     Hybrid Journal   (Followers: 12)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 13)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 12)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 3)
Cement and Concrete Composites     Hybrid Journal   (Followers: 8)
Change Over Time     Full-text available via subscription   (Followers: 3)
Civil and Environmental Research     Open Access   (Followers: 12)
Civil Engineering     Hybrid Journal   (Followers: 11)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 5)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 4)
Civil Engineering and Technology     Open Access   (Followers: 2)
Civil Engineering Dimension     Open Access   (Followers: 3)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 37)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 8)
Computers & Structures     Hybrid Journal   (Followers: 18)
Concrete Research Letters     Open Access   (Followers: 1)
Constructii : Journal of Civil Engineering Research     Open Access   (Followers: 5)
Construction Engineering     Open Access   (Followers: 3)
Construction Management and Economics     Hybrid Journal   (Followers: 27)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 12)
Enfoque UTE     Open Access   (Followers: 2)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 4)
Engineering Structures     Hybrid Journal   (Followers: 12)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 16)
Environmental Geotechnics     Open Access  
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 3)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 12)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access   (Followers: 1)
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 4)
Geomaterials     Open Access   (Followers: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 3)
Geotechnik     Hybrid Journal  
Géotechnique Letters     Hybrid Journal   (Followers: 3)
HBRC Journal     Open Access   (Followers: 1)
HVAC&R Research     Hybrid Journal   (Followers: 1)
Indoor and Built Environment     Hybrid Journal   (Followers: 1)
Ingenio Magno     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 5)
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: 5)
International Journal of Construction Engineering and Management     Open Access   (Followers: 3)
International Journal of Protective Structures     Full-text available via subscription   (Followers: 5)
International Journal of Steel Structures     Hybrid Journal   (Followers: 4)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 7)
International Journal of Structural Integrity     Hybrid Journal  
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Built Environment     Open Access   (Followers: 2)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 7)
ISRN Civil Engineering     Open Access   (Followers: 4)
ISRN Power Engineering     Open Access   (Followers: 1)
Journal of Accessibility and Design for All     Open Access   (Followers: 3)
Journal of Applied Fire Science     Full-text available via subscription  
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 14)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 3)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 3)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Science     Open Access   (Followers: 10)
Journal of Civil Engineering Research     Open Access   (Followers: 9)
Journal of Civil Society     Hybrid Journal   (Followers: 2)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 1)
Journal of Composites     Open Access   (Followers: 8)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 9)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 19)
Journal of Construction Engineering     Open Access   (Followers: 3)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 21)
Journal of Construction Engineering, Technology & Management     Full-text available via subscription   (Followers: 3)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 6)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 1)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 2)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 1)
Journal of Green Building     Full-text available via subscription   (Followers: 7)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 5)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 13)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)

        1 2     

Journal Cover Structural and Multidisciplinary Optimization
   Journal TOC RSS feeds Export to Zotero [6 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1615-1488 - ISSN (Online) 1615-147X
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 1.273]   [H-I: 54]
  • Probabilistic measures for assessing appropriateness of robust design
           optimization solutions
    • Abstract: Robust design optimization (RDO) is a popular framework for addressing uncertainties in the design of engineering systems by considering different statistical measures, typically the mean and standard deviation of the system response. RDO can lead to a wide range of different candidate designs, establishing a different compromise between these competing objectives. This work introduces a new robustness measure, termed probability of dominance, for assessing the appropriateness of each candidate design. This measure is defined as the likelihood that a particular design will outperform the rival designs within a candidate set. Furthermore, a multi-stage implementation is introduced to facilitate increased versatility/confidence in the decision-making process by considering the comparison among smaller subsets within the initial larger set of candidate designs. For enhancing the robustness in these comparisons the impact of prediction errors, introduced to address potential differences between the real (i.e. as built) system and the numerical model adopted for it, is also addressed. This extends to proper modeling of the influence of the prediction error, including selection of its probability model, as well as evaluation of its impact on the probability of dominance and on the RDO formulation itself. Two illustrative examples are presented, the first considering the design of a tuned mass damper (TMD) for vibration mitigation of harmonic excitations and the second a topology optimization problem for minimum compliance. Extensive comparisons are presented in these two examples and the discussions demonstrate the power of the proposed approach for assessing the designs’ robustness.
      PubDate: 2014-10-15
  • An importance boundary sampling method for reliability-based design
           optimization using kriging model
    • Abstract: Reliability-based design optimization (RBDO) combined with metamodel is a powerful tool to deal with variation of system output induced by uncertainties during practical engineering design. In this paper, the importance boundary sampling (IBS) method is proposed to enhance the efficiency of Kriging-model-based RBDO. Rather than fitting all the parts of the limit state constraints precisely within the design region, the proposed IBS mainly selects sample points on the critical parts of the limit state constraints. Two importance coefficients are proposed to identify these critical boundary parts: the first importance coefficient is determined by the objective function value; and the second one is calculated using the joint probability density value of the design variables. The sampling and optimization processes are conducted alternately to select the sample points more rationally. The computation capability of the proposed method is demonstrated using several mathematical RBDO problems and a box girder design application. The comparison results show that the proposed IBS method is very efficient.
      PubDate: 2014-10-15
  • A framework of model validation and virtual product qualification with
           limited experimental data based on statistical inference
    • Abstract: Virtual testing is a recent engineering development trend to design, evaluate, and test new engineered products. This research proposes a framework of virtual testing based on statistical inference for new product development comprising of three successive steps: (i) statistical model calibration, (ii) hypothesis test for validity check and (iii) virtual qualification. Statistical model calibration first improves the predictive capability of a computational model in a calibration domain. Next, the hypothesis test is performed with limited observed data to see if a calibrated model is sufficiently predictive for virtual testing of a new product design. An area metric and the u-pooling method are employed for the hypothesis test to measure the degree of mismatch between predicted and observed results while considering statistical uncertainty in the area metric due to the lack of experimental data. Once the calibrated model becomes valid, the virtual qualification process can be executed with a qualified model for new product developments. The qualification process builds a design decision matrix to aid in rational decision-making for product design alternatives. The effectiveness of the proposed framework is demonstrated through the case study of a tire tread block.
      PubDate: 2014-10-15
  • 11th World congress on structural and multidisciplinary optimization
    • PubDate: 2014-10-08
  • Cable stretching force optimization of concrete cable-stayed bridges
           including construction stages and time-dependent effects
    • Abstract: This paper presents an optimization algorithm to compute the prestressing forces on concrete cable-stayed bridges to achieve the desired final geometry. The structural analysis includes the load history and geometry changes due to the construction sequence and the time-dependent effects due to creep, shrinkage and aging of the concrete. An entropy-based approach was used for structural optimization and discrete direct sensitivity analysis was used to evaluate the structural response to changes in the design variables. Numerical examples are presented and the results exhibit the importance of considering both the construction stages and the time-dependent effects for adequately predict the bridge behaviour and compute the cable prestressing forces.
      PubDate: 2014-10-04
  • A flow topology optimization method for steady state flow using transient
           information of flow field solved by lattice Boltzmann method
    • Abstract: A topology optimization method for fluid flow using transient information is proposed. In many conventional methods, the design domain is updated using steady state information which is obtained after solving the flow field equations completely. Hence we must solve the flow field at each iterative which leads to high computational cost. In contrast, the proposed method updates the design domain using transient information of flow field. Hence the flow field is solved only once. The flow field is solved by lattice Boltzmann method (LBM). It is found that, by using LBM, the flow field is stably computed even though the design domain drastically changes during the computation. The design domain is updated according to sensitivity analysis. In many conventional methods, the sensitivity of objective functionals under lattice Boltzmann equations is obtained using additional adjoint equations. However, in the proposed method, the sensitivity is explicitly formulated and computed without using adjoint variables. In this paper, we show some numerical examples for low Reynolds number flows. The results demonstrate good convergence property in small computation time.
      PubDate: 2014-10-03
  • Advances in optimization of highrise building structures
    • Abstract: This paper presents a review of interesting work on optimization of highrise building structures with a focus on large-scale and real-life structures. A number of interesting projects with an eye on practicality are reviewed, a few involving practicing designers of highrise building structures. A review of literature indicates that performing a formal optimization can result in cost savings in the range of 5 to 15 % which can be especially significant in design of highrise and superhighhrise building structures. Since optimization of highrise building structures is a large-scale optimization problem the choice of the optimization approach is an important one. It should be one that is not entrapped in a local optimum solution and is stable for large-scale optimization subjected to discontinuous constraints of commonly-used design codes. The nature-based optimization approaches such as the neural dynamics model of Adeli and Park and genetic algorithms appear to be the preferred choice.
      PubDate: 2014-10-03
  • ISOCOMP: Unified geometric and material composition for optimal topology
    • Abstract: In this paper, a unified strategy is developed to simultaneously insert inclusions or holes of regular shape as well as redistribute the material to effect optimal topologies of solids. We demonstrate the unified optimal design strategy through three possible choices of design variables: (1) purely geometrical, (2) purely material, and (3) geometrical-material. We couple the geometrical approach with the topological derivative of the objective function and a condition derived for optimally inserting an infinitesimal ellipsoidal heterogeneity (hole or inclusion) into the structure. The approximations of the geometry, material and behavioral fields are isoparametric (or “isogeometric”) and are composed consistent with the Hierarchical Partition of Unity Field Compositions (HPFC) theory (Rayasam et al., Int J Numer Methods Eng 72(12):1452–1489, 2007). Specifically, analogous to the constructive solid geometry procedure of CAD, the complex material as well as the behavioral field is modeled hierarchically through a series of pair-wise compositions of primitive fields defined on the primitive geometrical domains. The geometrical, material and behavioral approximations are made using Non-Uniform Rational B-Splines (NURBS) basis functions. Thus, the proposed approach seamlessly unifies the explicit representation of boundary shapes with the implicit representations of boundaries arising out of material redistribution, and is termed ISOCOMP, or isoparametric compositions for topology optimization. The methodology is demonstrated first on a set of example problems that increase in complexity of design variable choice culminating in simultaneous optimization of hole location, hole shape and material distribution within the domain. This is followed by a detailed case study involving topology optimization of a bicycle “dropout.”
      PubDate: 2014-10-02
  • Multi-objective topology optimization of multi-component continuum
           structures via a Kriging-interpolated level set approach
    • Abstract: This paper explores a framework for topology optimization of multi-component sheet metal structures, such as those often used in the automotive industry. The primary reason for having multiple components in a structure is to reduce the manufacturing cost, which can become prohibitively expensive otherwise. Having a multi-component structure necessitates re-joining, which often comes at sacrifices in the assembly cost, weight and structural performance. The problem of designing a multi-component structure is thus posed in a multi-objective framework. Approaches to solve the problem may be classified into single and two stage approaches. Two-stage approaches start by focusing solely on structural performance in order to obtain optimal monolithic (single piece) designs, and then the decomposition into multiple components is considered without changing the base topology (identical to the monolithic design). Single-stage approaches simultaneously attempt to optimize both the base topology and its decomposition. Decomposition is an inherently discrete problem, and as such, non-gradient methods are needed for single-stage and second stage of two-stage approaches. This paper adopts an implicit formulation (level-sets) of the design variables, which significantly reduces the number of design variables needed in either single or two stage approaches. The number of design variables in the formulation is independent from the meshing size, which enables application of non-gradient methods to realistic designs. Test results of a short cantilever and an L-shaped bracket studies show reasonable success of both single and two stage approaches, with each approach having different merits.
      PubDate: 2014-10-02
  • Probabilistic sensitivity analysis for novel second-order reliability
           method (SORM) using generalized chi-squared distribution
    • Abstract: Reliability-based design optimization (RBDO) requires evaluation of sensitivities of probabilistic constraints. To develop RBDO utilizing the recently proposed novel second-order reliability method (SORM) that improves conventional SORM approaches in terms of accuracy, the sensitivities of the probabilistic constraints at the most probable point (MPP) are required. Thus, this study presents sensitivity analysis of the novel SORM at MPP for more accurate RBDO. During analytic derivation in this study, it is assumed that the Hessian matrix does not change due to the small change of design variables. The calculation of the sensitivity based on the analytic derivation requires evaluation of probability density function (PDF) of a linear combination of non-central chi-square variables, which is obtained by utilizing general chi-squared distribution. In terms of accuracy, the proposed probabilistic sensitivity analysis is compared with the finite difference method (FDM) using the Monte Carlo simulation (MCS) through numerical examples. The numerical examples demonstrate that the analytic sensitivity of the novel SORM agrees very well with the sensitivity obtained by FDM using MCS when a performance function is quadratic in U-space and input variables are normally distributed. It is further shown that the proposed sensitivity is accurate enough compared with FDM results even for a higher order performance function.
      PubDate: 2014-10-01
  • Multidisciplinary multifidelity optimisation of a flexible wing aerofoil
           with reference to a small UAV
    • Abstract: Abstract The preliminary Multidisciplinary Design and Optimisation of a flexible wing aerofoil apropos a small Unmanned Air Vehicle is performed using a multifidelity model-based strategy. Both the passively adaptive structure and the shape of the flexible wing aerofoil are optimised for best aerodynamic performance under aero-structural constraints, within a coupled aeroelastic formulation. A typical flight mission for surveillance purposes is considered and includes the potential occurrence of wind gusts. A metamodel for the high-fidelity objective function and each of the constraints is built, based on a tuned low-fidelity one, in order to improve the efficiency of the optimisation process. Both metamodels are based on solutions of the aeroelastic equations for a flexible aerofoil but employ different levels of complexity and computational cost for modelling aerodynamics and structural dynamics within a modal approach. The high-fidelity model employs nonlinear Computational Fluid Dynamics coupled with a full set of structural modes, whereas the low-fidelity one employs linear thin aerofoil theory coupled with a reduced set of structural modes. The low-fidelity responses are then corrected according to few high-fidelity responses, as prescribed by an appropriate Design of Experiment, by means of a suitable tuning technique. A standard Genetic Algorithm is hence utilised to find the global optimum, showing that a flexible aerofoil is characterised by higher aerodynamic efficiency than its rigid counterpart. Wing weight reduction is also accomplished when a Multiobjective Genetic Algorithm is adopted.
      PubDate: 2014-10-01
  • Seismic optimum design of triple friction pendulum bearing subjected to
           near-fault pulse-like ground motions
    • Abstract: Abstract Triple Friction Pendulum Bearing (TFPB) as a novel seismic isolator, provides different combinations of stiffness and damping during its course of motion. The adaptive behavior of TFPBs is one of the practical solutions for unsuitable performance of seismic isolation systems under near-fault ground motions. Selecting the TFPB’s design variables (curvature radii, friction coefficients and displacement capacity of sliding surfaces) is complicated process while finding the optimized combination of these variables depends on input ground motion characteristics and seismic performance objectives of the superstructure. Here first, comprehensive nonlinear dynamic analyses are performed to identify influence of the design variables on superstructure response (roof acceleration and displacement of isolated level). Next, a specific numerical optimization method based on Genetic Algorithms (GA) is applied to determine the optimum values of the design variables that minimize superstructure demands. In this process, near-fault ground motions are employed with ranges of pulse periods and hazard levels as input excitations. According to GA results, the derived optimum design variables of TFPB have significantly distinct intervals for different target responses such as story drift and TFPB displacement. Therefore response targets (single objective functions) are combined to make a new fitness function. The proposed optimization method for determining design variables and design intervals can be used for investigating many other types of superstructures with similar behaviors.
      PubDate: 2014-10-01
  • Material interface effects on the topology optimizationof multi-phase
           structures using a level set method
    • Abstract: A level set method is used as a framework to study the effects of including material interface properties in the optimization of multi-phase elastic and thermoelastic structures. In contrast to previous approaches, the material properties do not have a discontinuous change across the interface that is often represented by a sharp geometric boundary between material regions. Instead, finite material interfaces with monotonic and non-monotonic property variations over a physically motivated interface zone are investigated. Numerical results are provided for several 2D problems including compliance and displacement minimization of structures composed of two and three materials. The results highlight the design performance changes attributed to the presence of the continuously graded material interface properties.
      PubDate: 2014-10-01
  • Eigenvalue topology optimization of structures using a parameterized level
           set method
    • Abstract: Preventing a structure from resonance is important in many real-world applications. Because an external excitation frequency can be lower than the fundamental eigenfrequency or between the eigenfrequencies of a structure, there is a strong need for eigenfrequency optimization technology to optimize the fundamental eigenfrequency and, in addition, the k-th eigenfrequency and to maximize the gap between eigenfrequencies. However, previous optimization studies on vibrating elastic structures that used the level set method have been devoted to the optimization of the fundamental eigenfrequency, whereas the higher-order eigenfrequencies optimization problem has seldom been considered. This paper presents an eigenfrequency optimization technology that is based on the compactly supported radial basis functions (CS-RBFs) parameterized level-set method, using the fundamental eigenfrequency, the eigenfrequency of a given higher-order, and the gap between two consecutive eigenfrequencies as the optimization objectives. Furthermore, to address the oscillation problem of the objective function, we adopt an exponential weighted optimization model of a number of the lower eigenfrequencies for multiple eigenvalue optimizations, and we utilize mode-tracking technology for the single eigenvalue optimization.In addition, we further extend the CS-RBFs parameterized level-set method to an optimization that is performed with geometric constraints, which means that the size and position of the regular holes in the structure can be optimized with the shape and topology. This approach is useful in real-world applications. The effectiveness of this method is demonstrated by several widely investigated examples that have various objectives.
      PubDate: 2014-10-01
  • The gradient projection method for structural topology optimization
           including density-dependent force
    • Abstract: This paper proposes a modified gradient projection method (GPM) that can solve the structural topology optimization problem including density-dependent force efficiently. The particular difficulty of the considered problem is the non-monotonicity of the objective function and consequently the optimization problem is not definitely constrained. Transformation of variables technique is used to eliminate the constraints of the design variables, and thus the volume is the only possible constraint. The negative gradient of the objective function is adopted as the most promising search direction when the point is inside the feasible domain, while the projected negative gradient is used instead on condition that the point is on the hypersurface of the constraint. A rational step size is given via a self-adjustment mechanism that ensures the step size is a good compromising between efficiency and reliability. Furthermore, some image processing techniques are employed to improve the layouts. Numerical examples with different prescribed volume fractions and different load ratios are tested respectively to illustrate the characteristics of the topology optimization with density-dependent load.
      PubDate: 2014-10-01
  • Optimal SVM parameter selection for non-separable and unbalanced datasets
    • Abstract: This article presents a study of three validation metrics used for the selection of optimal parameters of a support vector machine (SVM) classifier in the case of non-separable and unbalanced datasets. This situation is often encountered when the data is obtained experimentally or clinically. The three metrics selected in this work are the area under the ROC curve (AUC), accuracy, and balanced accuracy. These validation metrics are tested using computational data only, which enables the creation of fully separable sets of data. This way, non-separable datasets, representative of a real-world problem, can be created by projection onto a lower dimensional sub-space. The knowledge of the separable dataset, unknown in real-world problems, provides a reference to compare the three validation metrics using a quantity referred to as the “weighted likelihood”. As an application example, the study investigates a classification model for hip fracture prediction. The data is obtained from a parameterized finite element model of a femur. The performance of the various validation metrics is studied for several levels of separability, ratios of unbalance, and training set sizes.
      PubDate: 2014-10-01
  • Topological optimization of two-dimensional phononic crystals based on the
           finite element method and genetic algorithm
    • Abstract: By using the finite element method and a “coarse to fine” two-stage genetic algorithm as the forward calculation method and the inverse search scheme, respectively, we perform both the unconstrained and constrained optimal design of the unit cell topology of the two-dimensional square-latticed solid phononic crystals (PnCs), to maximize the relative widths of the gaps between the adjacent energy bands of the PnCs. In the constrained optimizations, the maximization is subjected to the constraint of a predefined average density. In the numerical results, the variation patterns of the optimized structures with the order of the bandgap for both the out-plane shear and the in-plane mixed elastic wave modes are presented, and the effects of both the material contrast and the predefined average density on the obtained optimal structures are discussed.
      PubDate: 2014-10-01
  • Sensitivity analysis of structural response to position of external
           applied load: in plane stress condition
    • Abstract: Procedures for sensitivity analysis of the structural responses, i.e., nodal displacement, mean compliance and local stresses within an element, with respect to the location of an external applied load are developed. This is mainly because the external loads are often of some freedom to change their application positions in the structural preliminary design. Apart from the structural response evaluation, the finite element method is employed in this work for the sensitivity analysis implementation of a plane stress continuum structure. First, an external load is transformed into the equivalent nodal forces such that the influence of an external load shift is represented completely by the magnitude variation of the associated nodal forces, upon which the first- and second-order derivatives of an external load to its location change are performed respectively in a closed form by the aid of the features of the element shape functions. Then, the relevant sensitivities of the structural responses aforementioned are formulated readily with the discrete method. Finally, two typical examples are provided to demonstrate the validity of the sensitivity formulations presented, and the numerical results show a perfect accuracy of calculation of the response sensitivity.
      PubDate: 2014-10-01
  • A confirmation of a conjecture on the existence of symmetric optimal
           solution under multiple loads
    • Abstract: In this note, a conjecture on the existence of symmetric optimal solution under multiple loads made in Rozvany (Struct Multidisc Optim 43:297–317, 2011, Conjecture 4) has been confirmed.
      PubDate: 2014-10-01
  • Structural topology optimization with constraints on multi-fastener joint
    • Abstract: This paper addresses an important problem of design constraints on fastener joint loads that are well recognized in the design of assembled aircraft structures. To avoid the failure of fastener joints, standard topology optimization is extended not only to minimize the structural compliance but also to control shear loads intensities over fasteners. It is shown that the underlying design scheme is to ameliorate the stiffness distribution over the structure in accordance with the control of load distributions over fastener joints. Typical examples are studied by means of topology optimization with joint load constraints and the standard compliance design. The effects of joint load constraints are highlighted by comparing numerical optimization results obtained by both methods. Meanwhile, resin models of optimized designs are fabricated by rapid prototyping process for loading test experiments to make sure the effectiveness of the proposed method.
      PubDate: 2014-10-01
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