1. Optimiranje oblike konstrukcij: tristranični projektni elementMarko Kegl, 2002, original scientific article Abstract: Prispevek obravnava izpeljavo tristraničnega projektnega elementa za uporabo pri optimalnem projektiranju oblike konstrukcij. Osnova za izpeljavo novega elementa je tristranična Bézierjeva ploskev, ki je običajno parameterizirana z uporabo težiščnih koordinat. V prispevku je uporabljena drugačna parameterizacija, ki je bolj prilagojena postopkom optimizacije oblike. Na podlagi te ploskve je definiran projektni element-Bézierjevo telo, katerega mreža nadzornih točk ima v tipološkem pomenu obliko tristranične prizme. Uporaba izpeljanega elementa je ponazorjena na dveh številčnih zgledih.
Keywords: structural design, shape optimization, element design
Published in DKUM: 10.07.2015; Views: 1582; Downloads: 35
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2. Basic solutions on shape complexity evaluation of STL dataBogdan Valentan, Tomaž Brajlih, Igor Drstvenšek, Jože Balič, 2008, original scientific article Abstract: Purpose of this paper is to present basic solutions on shape complexity, based on basic information of the STL data. Design/methodology/approach: Paper presents a few methods of mathematically evaluating the complexity of the shape. Methods vary from very simple based on the number of triangles in STL file, STL file size and the parts volume, to the more complex mathematical evaluation based on the basic relations of the STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic results on part complexity and can be used for further researches. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: In a rapidly developing field of manufacturing technologies choosing the optimal manufacturing procedure is a difficult and crucial decision. Usually the decision is based on experience evaluation that is fast and can be optimal. Usually, this method produces goods results, but in some cases this method can lead to cost increases and reduced economic efficiency without us even knowing that. Therefore, it is crucial, that a fast and simple solution is developed, by which the optimal way of manufacturing can be determined. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.
Keywords: manufacturing systems, shape complexity, complex shapes, manufacturing optimization, engineering design, STL files, STL file parameters
Published in DKUM: 01.06.2012; Views: 2098; Downloads: 67
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3. Efficient handling of stability problems in shell optimization by asymmetric "worst case" shape imperfectionMarko Kegl, Boštjan Brank, Boštjan Harl, Maks Oblak, 2008, original scientific article Keywords: mechanics of structures, optimization of structures, stability, shells, imperfection, shape design
Published in DKUM: 01.06.2012; Views: 2429; Downloads: 111
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5. Optimization of elastic systems using absolute nodal coordinate finite element formulationBojan Vohar, Marko Kegl, Zoran Ren, 2006, other scientific articles Abstract: An approach to a shape optimization of elastic dynamic multibody systems is presented. The proposed method combines an appropriate shape parameterization concept and recently introduced finite element type using absolute nodal coordinate formulation (ANCF). In ANCF, slopes and displacements are used as the nodal coordinates instead of infinitesimal or finite rotations. This way one avoids interpolation of rotational coordinates and problems with finite rotations. ANCF elements are able to describe nonlinear deformation accurately; therefore, this method is very useful for simulations of lightweight multibody structures, where large deformations have to be taken into account. The optimization problem is formulated as a nonlinear programming problem and a gradient-based optimization procedure is implemented. The introduced optimization design variables are related to the cross-sectional parameters of the element and to the shape of the whole structure. The shape parameterization is based on the design element techniqueand a rational B ezier body is used as a design element. A body-like design element makes possible to unify the shape optimization of both simple beams and beam-like (skeletal) structures.
Keywords: mechanics, dynamics of material systems, multibody systems, elastic mechanical systems, manipulators, dynamically loaded beams, optimum shape design, absolute nodal coordinate formulation, design element technique, finite element method
Published in DKUM: 31.05.2012; Views: 2227; Downloads: 122
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6. Shape optimization of truss-stiffened shell structures with variable thicknessMarko Kegl, Boštjan Brank, 2006, original scientific article Abstract: 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.
Keywords: mechanics of structures, shape optimization, shells, trusses, Bézier body, numerical methods, optimum design
Published in DKUM: 30.05.2012; Views: 2136; Downloads: 120
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