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  Subjects -> ENGINEERING (Total: 1964 journals)
    - CHEMICAL ENGINEERING (151 journals)
    - CIVIL ENGINEERING (148 journals)
    - ELECTRICAL ENGINEERING (81 journals)
    - ENGINEERING (1120 journals)
    - ENGINEERING MECHANICS AND MATERIALS (293 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CIVIL ENGINEERING (148 journals)                  1 2     

ACI Structural Journal     Full-text available via subscription   (Followers: 4)
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: 22)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 18)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 15)
Architectural Engineering     Open Access   (Followers: 3)
Archives of Civil Engineering     Open Access   (Followers: 6)
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: 2)
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: 4)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 10)
Building and Environment     Hybrid Journal   (Followers: 10)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 12)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 10)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 3)
Cement and Concrete Composites     Hybrid Journal   (Followers: 6)
Change Over Time     Full-text available via subscription   (Followers: 3)
Civil and Environmental Research     Open Access   (Followers: 11)
Civil Engineering     Hybrid Journal   (Followers: 9)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 4)
Civil Engineering and Technology     Open Access   (Followers: 1)
Civil Engineering Dimension     Open Access   (Followers: 3)
Cohesion and Structure     Full-text available via subscription   (Followers: 1)
Composite Structures     Hybrid Journal   (Followers: 33)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 7)
Computers & Structures     Hybrid Journal   (Followers: 13)
Concrete Research Letters     Open Access   (Followers: 1)
Constructii : Journal of Civil Engineering Research     Open Access   (Followers: 4)
Construction Engineering     Open Access   (Followers: 3)
Construction Management and Economics     Hybrid Journal   (Followers: 25)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 10)
Enfoque UTE     Open Access   (Followers: 1)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 4)
Engineering Structures     Hybrid Journal   (Followers: 11)
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: 2)
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: 1)
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: 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: 6)
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: 3)
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: 4)
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: 13)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 3)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 2)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 4)
Journal of Civil Engineering and Science     Open Access   (Followers: 9)
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  
Journal of Composites     Open Access   (Followers: 6)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 8)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 17)
Journal of Construction Engineering     Open Access   (Followers: 3)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 20)
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: 6)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 4)
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
   [5 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  [2208 journals]   [SJR: 1.273]   [H-I: 54]
  • Driving force profile design in comb drive electrostatic actuators using a
           level set-based shape optimization method
    • Abstract: Abstract Electrostatic actuators, actuators actuated by electrostatic forces, are now widely used as sensors and switches, especially in Micro-Electro-Mechanical Systems (MEMS). Among different kinds of electrostatic actuators, the comb drive type is one of the most popular because it has a relatively large range of displacement. In design problems for electrostatic actuators, the driving force profile is of primary engineering importance. In this paper, we develop a structural optimization method for comb drive electrostatic actuators that achieves prescribed driving force profiles, based on a level set-based shape optimization method that provides optimal configurations with clear boundaries, solutions that are valid in an engineering sense. Accurate calculation of the electrostatic forces that occur on the structural boundaries during optimization is important for developing actuators that operate with prescribed driving forces. In the conventional level set-based shape optimization methods, inaccuracies in the calculation of these electrostatic forces occur because the structural boundaries are seldom aligned with the finite element method (FEM) nodes. To precisely calculate the electrostatic forces, we developed a mesh adaptation scheme by which the finite element nodes are brought into alignment with the structural boundaries at every iteration of the optimization procedure. In the following, we explain the details of the proposed level set-based shape optimization method, in which a multi-objective optimization problem is formulated to achieve a prescribed driving force profile. The sensitivity is derived using the adjoint variable method. Four numerical examples are provided, to examine the suitability of the proposed optimization method.
      PubDate: 2014-07-20
       
  • Actuator topology design using the controllability Gramian
    • Abstract: Abstract This work develops a methodology for the optimal design of actuators for the vibration control of flexible structures. The objective is the maximization of a measure of the controllability Gramian. The test case is the embedding of piezoelectric inserts in elastic structures for vibration control in modal space. A topology optimization was formulated to distribute two material phases in the domain: a passive linear elastic material and an active linear piezoelectric material, with a volume constraint in the latter. The objective function is the trace of the controllability Gramian of a LQR control system. Analytical sensitivities for the finite element model are derived for the objective function and constraints. Results are shown for two dimensional vibration control of a short beam with varying number of electrodes (control inputs) and vibration modes.
      PubDate: 2014-07-16
       
  • Optimal SVM parameter selection for non-separable and unbalanced datasets
    • Abstract: 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: 2014-07-08
       
  • Robust optimal design of tuned mass dampers for tall buildings with
           uncertain parameters
    • Abstract: Abstract In this paper a newly proposed approach to robust optimization is adopted in order to study the influence of uncertain structural parameters on the design of a passive control system The control devices are Tuned Mass Dampers placed on a tall building subjected to wind load. The uncertain structural variables are the floors’ mass and stiffness. The spatial variability of the mass over the floor’s surface is considered by ideally dividing each floor into a certain number of partitions in which the mass varies as a random variable. The robust optimization procedure is based on an enhanced Monte Carlo simulation technique and the genetic algorithm. The Latin Hypercube Sampling is employed to reduce the number of samples. The optimization of stiffnesses and dampings of the devices is carried out for each sample set of structural mass and stiffness matrices, allowing the evaluation of the probability distributions of the optimal parameters and the objective function. The robust designs are those having corresponding values of the objective function lying in the neighborhood of the expected value of the distribution The robust optimization is applied to a tall building controlled by a Tuned Mass Damper and subjected to wind loads obtained from wind tunnel tests. Several numerical analyses are carried out considering different numbers of surface partitions. Both the separate and joint influence of the mass and stiffness uncertainty is considered. The results show that the selected designs are robust, as they guarantee a small variability of structural performance caused by uncertainties.
      PubDate: 2014-07-05
       
  • Isogeometric configuration design optimization of built-up structures
    • Abstract: Abstract We derive the isogeometric configuration sensitivity of the Mindlin plates by using the material derivative and adjoint approaches. This is utilized in the shape design optimization that includes a variation of design components in its shape and orientation. By the isogeometric approach, the NURBS basis function in CAD system is directly utilized in the response analysis, which enables the seamless incorporation of higher continuity and exact geometry such as curvature and normal vector into the computational framework. The impact of exact curvature in the bending problem of Mindlin plates on the configuration design sensitivity is demonstrated through numerical examples. The obtained design sensitivity is further utilized in the shape design optimization of built-up structures. Due to the non-interpolatory property of the NURBS basis functions, a mismatch of patches in the built-up structures could occur during the isogeometric design optimization, which can be easily resolved using transformed basis functions.
      PubDate: 2014-07-04
       
  • Multiobjective optimization using an aggregative gradient-based method
    • Abstract: Abstract A process of compromise that addresses conflicting objective functions such as performance and cost is often involved in real-world engineering design activities. If such conflicting relationships among objective functions exist in a multiobjective design optimization problem, no single solution can simultaneously minimize all objective functions, and the solutions of the optimization problem are obtained as a set of design alternatives called a Pareto optimal solution set. This paper proposes a new gradient-based multiobjective c that incorporates a population-based aggregative strategy for obtaining a Pareto optimal solution set. In this method, the objective functions and constraints are evaluated at multiple points in the objective function space, and design variables at each point are updated using information aggregatively obtained from all other points. In the proposed method, a multiobjective optimization problem is converted to a single objective optimization problem using a weighting method, with weighting coefficients adaptively determined by solving a linear programming problem. A sequential approximate optimization-based technique is used to update the design variables, since it allows effective use of design sensitivities that can be easily obtained in many engineering optimization problems. Several numerical examples, including a structural optimization problem, are provided to illustrate the effectiveness and utility of the proposed method.
      PubDate: 2014-07-02
       
  • Resolving issues with member buckling in truss topology optimization using
           a mixed variable approach
    • Abstract: Abstract In this paper, several issues related to member buckling in truss topology optimization are treated. In the conventional formulations, where cross-sectional areas of ground structure members are the design variables, member buckling constraints are known to be very difficult to handle, both numerically and theoretically. Buckling constraints produce a feasible set that is non-connected and non-convex. Furthermore, the so-called jump in the buckling length phenomenon introduces severe difficulties for determining the correct buckling strength of parallel consecutive compression members. These issues are handled in the paper by employing a mixed variable formulation of truss topology optimization problems. In this formulation, member buckling constraints become linear. Parallel consecutive members of the ground structure are identified as chains, and overlapping members are added to the ground structure between each pair of nodes of a chain. Buckling constraints are written for every member, and linear constraints on the binary member existence variables disallow impractical topologies. In the proposed approach, Euler buckling as well as buckling according to various design codes, can be incorporated. Numerical examples demonstrate that the optimum topology depends on whether the buckling constraints are derived from Euler’s theory or from design codes.
      PubDate: 2014-07-01
       
  • Fatigue reliability analysis for structures with known loading trend
    • Abstract: Abstract Variations, such as those in product operation environment and material properties, result in random fatigue life. Variations in material fatigue properties depend on stochastic stress responses due to their nonlinear relationships with other random variables such as stochastic loading and dimensions. In this work, an efficient fatigue reliability analysis method is developed to accommodate those uncertainties for structures under cyclic loads with known loading trend. To reduce the computational cost, the method incorporates the fatigue life analysis model and the saddlepoint approximation method with the fast integration method. The new method is applied to the fatigue reliability analysis of a cantilever beam and a door cam. The results show high accuracy and efficiency of the proposed method benchmarked with Monte Carlo Simulations.
      PubDate: 2014-07-01
       
  • Backward walking simulation of humans using optimization
    • Abstract: Abstract The objective of this study is to formulate, simulate and study the backward walking motion of a full-body skeletal digital human model using an optimization approach. Predictive dynamics is used to simulate the task in which joint angle profiles are treated as primary unknowns in the formulation. The joint torques are treated as dependent variables that are evaluated directly from the equations of motion. For the performance measure, the normalized dynamic effort represented by the integral of the squares of all the normalized joint torques is minimized subject to the associated physical constraints. Backward walking at different speeds is simulated and analyzed. The backward walking is validated with motion capture data and the available data in the literature. The results of the backward walking motion are compared to those of the forward walking motion in order to study the differences between the two walking patterns. It is seen that the joint torque profiles for hip and knee of backward walk are quite similar to those of forward walk with reverse sequence, but with different time duration of flexion and extension activations. These findings can impact many fields, such as improvement of human performance, rehabilitation from injuries, and others.
      PubDate: 2014-07-01
       
  • Implementation of set-based design in multidisciplinary design
           optimization
    • Abstract: Abstract Set-based design is a design approach where feasible regions for the design variables are determined from different disciplines, with the goal of locating and working with the areas of feasible overlap. During the process the constraints are adjusted in order to accommodate conflicting requirements between disciplines. The main objective of set-based design is to narrow the design space, while delaying the pursuit of a single point design as much as possible. This process avoids finalizing decisions early and allows for flexibility in dealing with requirement creep. This paper presents the development and application of a new multidisciplinary design optimization (MDO) algorithm inspired by the principles of set-based design. The new MDO algorithm was developed with the core concept of describing the design using sets to incorporate features of set-based design and achieve greater flexibility than with a single-point optimization. The MDO algorithm was applied to a ship design problem and the ship design application demonstrated the value of utilizing set-based design as a space-reducing technique before approaching the problem with a point-based optimization. Furthermore, incorporating flexibility in the constraints allowed the optimization to handle a problem with very strict constraints in a rational manner and minimize the necessary constraint violation.
      PubDate: 2014-07-01
       
  • Aeroelastic tailoring and scaling using Bacterial Foraging Optimisation
    • Abstract: Abstract Bacterial Foraging Optimisation (BFO) is investigated in an attempt to evaluate its use in solving complex optimisation problems for aeronautical structures. A hybrid variant of BFOA, which incorporates meta-modelling techniques, is also proposed and employed. The efficiency and effectiveness of the methods are tested for tailoring a rectangular composite wing, aiming to maximise the flutter speed and for scaling a joined-wing aircraft, targeting to match aeroelastic responses between the physical prototype and wind tunnel model. The obtained results are compared with those found using a range of other biologically inspired optimisation methods (GA, PSO, ACO), proving that the social foraging behavior of motile bacteria is an effective tool for aeroelastic optimisation.
      PubDate: 2014-07-01
       
  • On the layout of a least weight single 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. The methodology utilized takes advantage of the properties of reciprocal diagrams (as described by the authors in a previous paper). Therefore, the optimization is conducted on the dual truss associated with the force diagram of the original structure rather than on the original structure itself. An analytical expression for the volume of the dual truss, which coincides with that of the original truss, is also derived in the form of a functional. Numerical integration is then conducted on the functional to obtain the optimal layout, and the numerical sensitivity of the solution with respect to the selection of the approximation function is investigated. The final results show that simple formulas describe the geometric properties of the dual (reciprocal) structure and thus the original truss. Finally, this paper shows that the results presented agree with previous numerical studies in the literature.
      PubDate: 2014-07-01
       
  • Optimizing inclusion shapes and patterns in periodic materials using
           Discrete Object Projection
    • Abstract: Abstract Current topology optimization methodologies assume a monolithic, free form approach to design. Many engineered materials and structures, however, are composed of discrete, non-overlapping objects such as fiber or particle-based materials. Application of the topology optimization methodology to these types of materials therefore requires controlling the shape and interaction of designed features to ensure solutions are meaningful and physically realizable. Achieving such control on continuum domains is challenging as features form via the union of elements of like phase. A topology optimization approach is proposed herein for optimizing the size, shape, and layout of inclusion-like features in a continuum domain. The technique is based on the Heaviside Projection Method and uses multiple regularized Heaviside functions whose interaction is tailored so that the designer may restrict the minimum and maximum length scale of inclusions, and minimum spacing between inclusions. The technique is demonstrated on the design of material microstructures with enhanced elastic stiffness.
      PubDate: 2014-07-01
       
  • Non-parametric free-form optimization method for frame structures
    • Abstract: Abstract In this paper, we propose a parameter-free shape optimization method based on the variational method for designing the smooth optimal free-form of a spatial frame structure. A stiffness design problem where the compliance is minimized under a volume constraint is solved as an example of shape design problems of frame structures. The optimum design problem is formulated as a distributed-parameter shape optimization problem under the assumptions that each member is varied in the out-of-plane direction to the centroidal axis and that the cross section is prismatic. The shape gradient function and the optimality conditions are then theoretically derived. The optimal curvature distribution is determined by applying the derived shape gradient function to each member as a fictitious distributed force both to vary the member in the optimum direction and to minimize the objective functional without shape parametrization, while maintaining the members’ smoothness. The validity and practical utility of this method were verified through several design examples. It was confirmed that axial-force-carrying structures were obtained by this method.
      PubDate: 2014-07-01
       
  • Integrated size and topology optimization of skeletal structures with
           exact frequency constraints
    • Abstract: Abstract The present paper studies the integrated size and topology optimization of skeletal structures under natural frequency constraints. It is found that, unlike the conventional compliance-oriented topology optimization problems, the considered problem may be strongly singular in the sense that the corresponding feasible domain may be disconnected and the global optimal solutions are often located at the tips of some separated low dimensional sub-domains when the cross-sectional areas of the structural components are used as design variables. As in the case of stress-constrained topology optimization, this unpleasant behavior may prevent the gradient-based numerical optimization algorithms from finding the true optimal topologies. To overcome the difficulties posed by the strongly singular optima, some particular forms of area/moment of inertia-density interpolation schemes, which can restore the connectedness of the feasible domain, are proposed. Based on the proposed optimization model, the probability of finding the strongly singular optimum with gradient-based algorithms can be increased. Numerical examples demonstrate the effectiveness of the proposed approach.
      PubDate: 2014-07-01
       
  • DMTO – a method for Discrete Material and Thickness Optimization of
           laminated composite structures
    • Abstract: Abstract This paper presents a gradient based topology optimization method for Discrete Material and Thickness Optimization of laminated composite structures, labelled the DMTO method. The capabilities of the proposed method are demonstrated on mass minimization, subject to constraints on the structural criteria; buckling load factors, eigenfrequencies, and limited displacements. Furthermore, common design guidelines or rules, referred to as manufacturing constraints, are included explicitly in the optimization problem as series of linear inequalities. The material selection and thickness variation are optimized simultaneously through interpolation functions with penalization. Numerical results for several parameterizations of a finite element model of a generic main spar from a wind turbine blade are presented. The different parameterizations represent different levels of complexity with respect to manufacturability. The results will thus give insight into the relation between potential weight saving and design complexity. The results show that the DMTO method is capable of solving the problems robustly with only few intermediate valued design variables.
      PubDate: 2014-07-01
       
  • Optimization of the machine foundation using frequency constraints
    • Abstract: Abstract Faced with the constantly increasing requirements for machine efficiency and reliability, designers have to pay attention to every detail, including machine foundation. Possible outage costs due to foundation damage can easily exceed the costs of design and construction of the foundation. This paper presents a novel and systematic procedure for finding an optimal design of reinforced concrete columns of the spring mounted machine foundation subjected to dynamic loads. The proposed approach assumes considerably decoupled natural modes of the critical structural members which can be optimized as simplified analytical models. It includes the following steps: FE modal analysis of the complete structure, identification of expected dynamic excitation, determination of the critical structural members, optimization of the corresponding analytical models and verification by FE modal analysis of the complete optimized structure. Turbine-generator-foundation structure was employed as an illustrative example. Operating speeds of the turbine and the generator and their higher order harmonics are taken as a critical dynamic excitation. Therefore, avoiding possible resonance region became the design objective, while the design variables were dimensions of the foundation columns cross-section. Lower and upper bounds of the design variables are determined on the basis of structural stability and space limitations regarding condenser and other auxiliary components of the turbine-generator system. The results of the analyzed example confirm that the optimization was successfully performed, since the optimized dimensions of the columns yielded natural frequencies outside the critical frequency range.
      PubDate: 2014-07-01
       
  • Analytical benchmark example for risk allocation in structural
           optimization
    • Abstract: Abstract Recently, Rozvany and Maute presented a simple problem of topology optimization under uncertainty with a single load condition that can be solved without Monte Carlo simulation. This note extends this idea to a two-bar truss under two load conditions for the purpose of illustrating differences between deterministic designs and reliability–based ones in terms of risk allocation. For this example, for the same probability of failure, a deterministic design based on the same safety factor for both loads can be substantially heavier than the reliability–based design. The difference in weight is due to very different risk allocation between the two failure modes.
      PubDate: 2014-07-01
       
  • NURBS modeling and structural shape optimization of cardiovascular stents
    • Abstract: Abstract Cardiovascular stents have been used since the 1990s to treat atherosclerosis, one of leading causes of death in the western world, and structural optimization has led to significant improvements in stent performance. Much of the potential variation in stent geometry, however, has remained unconsidered. This paper presents a non-uniform rational basis spline (NURBS) parameterization of a stent, the inclusion of structural fatigue resistance as a design consideration, and the results of a design optimization based on response surface techniques. Results show the feasibility and merits of the NURBS approach, which models a much broader range of shapes than was previously possible. Multi-objective optimization produces a range of geometrically diverse Pareto-optimal designs; these can be used to develop future clinical design guides, accounting for the variation observed across patients. We conclude by motivating future work with increasingly complex physical modeling and optimization capabilities.
      PubDate: 2014-07-01
       
  • An efficient 3D topology optimization code written in Matlab
    • Abstract: Abstract This paper presents an efficient and compact Matlab code to solve three-dimensional topology optimization problems. The 169 lines comprising this code include finite element analysis, sensitivity analysis, density filter, optimality criterion optimizer, and display of results. The basic code solves minimum compliance problems. A systematic approach is presented to easily modify the definition of supports and external loads. The paper also includes instructions to define multiple load cases, active and passive elements, continuation strategy, synthesis of compliant mechanisms, and heat conduction problems, as well as the theoretical and numerical elements to implement general non-linear programming strategies such as SQP and MMA. The code is intended for students and newcomers in the topology optimization. The complete code is provided in Appendix C and it can be downloaded from http://top3dapp.com.
      PubDate: 2014-06-25
       
 
 
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