1. The MINLP approach to topology, shape and discrete sizing optimization of trussesSimon Šilih, Zdravko Kravanja, Stojan Kravanja, 2022, izvirni znanstveni članek Opis: The paper presents the Mixed-Integer Non-linear Programming (MINLP) approach to the
synthesis of trusses. The solution of continuous/discrete non-convex and non-linear optimization
problems is discussed with respect to the simultaneous topology, shape and discrete sizing optimization of trusses. A truss MINLP superstructure of different topology and design alternatives
has been generated, and a special MINLP model formulation for trusses has been developed. In the
optimization model, a mass objective function of the structure has been defined and subjected to
design, load and dimensioning constraints. The MINLP problems are solved using the Modified
Outer-Approximation/Equality-Relaxation (OA/ER) algorithm. Multi-level MINLP strategies are introduced to accelerate the convergence of the algorithm. The Modified Two-Phase and the Sequential
Two-Phase MINLP strategies are proposed in order to solve highly combinatorial topology, shape
and discrete sizing optimization problems. The importance of local buckling constraints on topology
optimization is also discussed. Some simple numerical examples are shown at the end of the paper to
demonstrate the suitability and efficiency of the proposed method.
Ključne besede: structural synthesis, topology optimization, discrete sizing optimization, mixed-integer non-linear programming, MINLP, modified OA/ER algorithm, multi-level MINLP strategies, steel structures, trusses
Objavljeno v DKUM: 11.03.2025; Ogledov: 0; Prenosov: 3
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2. Optimum design of plane timber trusses considering joint flexibilitySimon Šilih, Miroslav Premrov, Stojan Kravanja, 2005, izvirni znanstveni članek Opis: The paper presents the optimization of metal-plate-connected plane timber trusses with special emphasis on joint flexibility. The optimization was performed by the non-linear programming approach. Since various truss design parameters such as type of truss configuration, span/depth ratio, number and type of diagonal and vertical members and type of joint connections simultaneously affect each other, it is proposed that all of these parameters should be considered simultaneously in a single mathematical model. An optimization model for cost optimization of timber trusses was thus developed. The economic objective function for minimizing the structure's self-manufacturing costs was defined, subjected to the design, stress and deflection (in)equality constraints. The finite element equations were as the equality constraints defined for the calculation of the internal forces and the deflections of the structure. The stiffness matrix of the structure was composed by considering fictitiously decreased cross-section areas of all the flexibly connected elements. Constraints for the dimensioning of the timber members were determined in accordance with Eurocode 5 in order to satisfy the requirements of both the ultimate and the serviceability limit states. The cross-section dimensions and the number of fasteners were defined as independent optimization variables. A numerical example demonstrates the applicability of the optimization approach presented as well as the influence of the fasteners' flexibility on the optimal self-manufacturing costs.
Ključne besede: civil engineering, timber structures, trusses, fasteners, flexibility, optimization, non-linear programming
Objavljeno v DKUM: 01.06.2012; Ogledov: 2275; Prenosov: 126
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4. Shape optimization of truss-stiffened shell structures with variable thicknessMarko Kegl, Boštjan Brank, 2006, izvirni znanstveni članek Opis: This paper presents an effective approach to shape optimal design of statically loaded elastic shell-like structures. The shape parametrization is based on a design element technique. The chosen design element is a rational Bézier body, enhanced with a smoothly varying scalar field. A body-like designelement makes possible to unify the shape optimization of both pure shells and truss-stiffened shell structures. The scalar field of the design element is obtained by attaching to each control point a scalar quantity, which is an add-on to the position and weight of the control point. This scalar field is linked to the shell thickness distribution, which can be optimized simultaneously with the shape of the shell. For linear and non-linear analysis of shell structures, a reliable 4-node shell finite element formulation is utilized. The presented optimization approach assumes the employment of a gradient-based optimization algorithm and the use of the discrete method of direct differentiation to perform the sensitivity analysis.Four numerical examples of shell and truss-stiffened shell optimization are presented in detail to illustrate the performance of the proposed approach.
Ključne besede: mechanics of structures, shape optimization, shells, trusses, Bézier body, numerical methods, optimum design
Objavljeno v DKUM: 30.05.2012; Ogledov: 2136; Prenosov: 123
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