From on-line sketching to 2D and 3D geometry: A fuzzy knowledge based system

The paper describes the development of a fuzzy knowledge based prototype system for conceptual design. This real time system is designed to infer user’s sketching intentions, to segment sketched input and generate corresponding geometric primitives: straight lines, circles, arcs, ellipses, elliptical arcs, and B-spline curves. Topology information (connectivity, unitary constraints and pairwise constraints) is received dynamically from 2D sketched input and primitives. From the 2D topology information, a more accurate 2D geometry can be built up by applying a 2D geometric constraint solver. Subsequently, 3D geometry can be received feature by feature incrementally. Each feature can be recognised by inference knowledge in terms of matching its 2D primitive configurations and connection relationships. The system accepts not only sketched input, working as an automatic design tools, but also accepts user’s interactive input of both 2D primitives and special positional 3D primitives. This makes it easy and friendly to use. The system has been tested with a number of sketched inputs of 2D and 3D geometry

Reverse engineering and refurbishing of an Mi-24 helicopter main gear box

The Mi-24 helicopter is one of the most famous heavy lift helicopters designed with a net weight of 8.4 tonnes, while its gross weight is 12.5 tonnes. This helicopter is powered by two TV3-117 turbo-engines, coupled to a VR-24 main rotor transmission gearbox, which reduces the engine speed from 15000 Revolutions Per Minute (RPM) to the main rotor speed of 240 RPM. This research aims to show the functionality of the Mi-24 helicopter main gear box, to find the opportunities to extend the running hours (before maintenance) and to refurbish the gear box locally in South Africa. The research follows the principles of Reverse Engineering (RE) and Refurbishing. The principles involve the extraction of information from an existing product in order to establish its function and to re-create specifications which can be used to make, maintain or refurbish a similar or superior item. This dissertation has exposed some of the theory of the design of the Mi-24 main gearbox components and their functionality; including similar selected helicopters’ main drive mechanisms. The probable defects that are common to helicopter transmissions, the specifications and the Computer Aided Design (CAD) drawings are also presented. The research concludes that, with the cooperation of the local aerospace industry (including the army), the academic institutions and government; it is possible to get the necessary certification, licensing, training, specialised equipment and to establish a Maintenance Organisation, to refurbish the Mi-24 helicopter gearbox locally in South Africa

Reverse engineering and refurbishing of an Mi-24 helicopter main gear box

The Mi-24 helicopter is one of the most famous heavy lift helicopters designed with a net weight of 8.4 tonnes, while its gross weight is 12.5 tonnes. This helicopter is powered by two TV3-117 turbo-engines, coupled to a VR-24 main rotor transmission gearbox, which reduces the engine speed from 15000 Revolutions Per Minute (RPM) to the main rotor speed of 240 RPM. This research aims to show the functionality of the Mi-24 helicopter main gear box, to find the opportunities to extend the running hours (before maintenance) and to refurbish the gear box locally in South Africa. The research follows the principles of Reverse Engineering (RE) and Refurbishing. The principles involve the extraction of information from an existing product in order to establish its function and to re-create specifications which can be used to make, maintain or refurbish a similar or superior item. This dissertation has exposed some of the theory of the design of the Mi-24 main gearbox components and their functionality; including similar selected helicopters’ main drive mechanisms. The probable defects that are common to helicopter transmissions, the specifications and the Computer Aided Design (CAD) drawings are also presented. The research concludes that, with the cooperation of the local aerospace industry (including the army), the academic institutions and government; it is possible to get the necessary certification, licensing, training, specialised equipment and to establish a Maintenance Organisation, to refurbish the Mi-24 helicopter gearbox locally in South Africa

Curve Skeleton and Moments of Area Supported Beam Parametrization in Multi-Objective Compliance Structural Optimization

This work addresses the end-to-end virtual automation of structural optimization up to the derivation of a parametric geometry model that can be used for application areas such as additive manufacturing or the verification of the structural optimization result with the finite element method. A holistic design in structural optimization can be achieved with the weighted sum method, which can be automatically parameterized with curve skeletonization and cross-section regression to virtually verify the result and control the local size for additive manufacturing. is investigated in general. In this paper, a holistic design is understood as a design that considers various compliances as an objective function. This parameterization uses the automated determination of beam parameters by so-called curve skeletonization with subsequent cross-section shape parameter estimation based on moments of area, especially for multi-objective optimized shapes. An essential contribution is the linking of the parameterization with the results of the structural optimization, e.g., to include properties such as boundary conditions, load conditions, sensitivities or even density variables in the curve skeleton parameterization. The parameterization focuses on guiding the skeletonization based on the information provided by the optimization and the finite element model. In addition, the cross-section detection considers circular, elliptical, and tensor product spline cross-sections that can be applied to various shape descriptors such as convolutional surfaces, subdivision surfaces, or constructive solid geometry. The shape parameters of these cross-sections are estimated using stiffness distributions, moments of area of 2D images, and convolutional neural networks with a tailored loss function to moments of area. Each final geometry is designed by extruding the cross-section along the appropriate curve segment of the beam and joining it to other beams by using only unification operations. The focus of multi-objective structural optimization considering 1D, 2D and 3D elements is on cases that can be modeled using equations by the Poisson equation and linear elasticity. This enables the development of designs in application areas such as thermal conduction, electrostatics, magnetostatics, potential flow, linear elasticity and diffusion, which can be optimized in combination or individually. Due to the simplicity of the cases defined by the Poisson equation, no experts are required, so that many conceptual designs can be generated and reconstructed by ordinary users with little effort. Specifically for 1D elements, a element stiffness matrices for tensor product spline cross-sections are derived, which can be used to optimize a variety of lattice structures and automatically convert them into free-form surfaces. For 2D elements, non-local trigonometric interpolation functions are used, which should significantly increase interpretability of the density distribution. To further improve the optimization, a parameter-free mesh deformation is embedded so that the compliances can be further reduced by locally shifting the node positions. Finally, the proposed end-to-end optimization and parameterization is applied to verify a linear elasto-static optimization result for and to satisfy local size constraint for the manufacturing with selective laser melting of a heat transfer optimization result for a heat sink of a CPU. For the elasto-static case, the parameterization is adjusted until a certain criterion (displacement) is satisfied, while for the heat transfer case, the manufacturing constraints are satisfied by automatically changing the local size with the proposed parameterization. This heat sink is then manufactured without manual adjustment and experimentally validated to limit the temperature of a CPU to a certain level.:TABLE OF CONTENT III I LIST OF ABBREVIATIONS V II LIST OF SYMBOLS V III LIST OF FIGURES XIII IV LIST OF TABLES XVIII 1. INTRODUCTION 1 1.1 RESEARCH DESIGN AND MOTIVATION 6 1.2 RESEARCH THESES AND CHAPTER OVERVIEW 9 2. PRELIMINARIES OF TOPOLOGY OPTIMIZATION 12 2.1 MATERIAL INTERPOLATION 16 2.2 TOPOLOGY OPTIMIZATION WITH PARAMETER-FREE SHAPE OPTIMIZATION 17 2.3 MULTI-OBJECTIVE TOPOLOGY OPTIMIZATION WITH THE WEIGHTED SUM METHOD 18 3. SIMULTANEOUS SIZE, TOPOLOGY AND PARAMETER-FREE SHAPE OPTIMIZATION OF WIREFRAMES WITH B-SPLINE CROSS-SECTIONS 21 3.1 FUNDAMENTALS IN WIREFRAME OPTIMIZATION 22 3.2 SIZE AND TOPOLOGY OPTIMIZATION WITH PERIODIC B-SPLINE CROSS-SECTIONS 27 3.3 PARAMETER-FREE SHAPE OPTIMIZATION EMBEDDED IN SIZE OPTIMIZATION 32 3.4 WEIGHTED SUM SIZE AND TOPOLOGY OPTIMIZATION 36 3.5 CROSS-SECTION COMPARISON 39 4. NON-LOCAL TRIGONOMETRIC INTERPOLATION IN TOPOLOGY OPTIMIZATION 41 4.1 FUNDAMENTALS IN MATERIAL INTERPOLATIONS 43 4.2 NON-LOCAL TRIGONOMETRIC SHAPE FUNCTIONS 45 4.3 NON-LOCAL PARAMETER-FREE SHAPE OPTIMIZATION WITH TRIGONOMETRIC SHAPE FUNCTIONS 49 4.4 NON-LOCAL AND PARAMETER-FREE MULTI-OBJECTIVE TOPOLOGY OPTIMIZATION 54 5. FUNDAMENTALS IN SKELETON GUIDED SHAPE PARAMETRIZATION IN TOPOLOGY OPTIMIZATION 58 5.1 SKELETONIZATION IN TOPOLOGY OPTIMIZATION 61 5.2 CROSS-SECTION RECOGNITION FOR IMAGES 66 5.3 SUBDIVISION SURFACES 67 5.4 CONVOLUTIONAL SURFACES WITH META BALL KERNEL 71 5.5 CONSTRUCTIVE SOLID GEOMETRY 73 6. CURVE SKELETON GUIDED BEAM PARAMETRIZATION OF TOPOLOGY OPTIMIZATION RESULTS 75 6.1 FUNDAMENTALS IN SKELETON SUPPORTED RECONSTRUCTION 76 6.2 SUBDIVISION SURFACE PARAMETRIZATION WITH PERIODIC B-SPLINE CROSS-SECTIONS 78 6.3 CURVE SKELETONIZATION TAILORED TO TOPOLOGY OPTIMIZATION WITH PRE-PROCESSING 82 6.4 SURFACE RECONSTRUCTION USING LOCAL STIFFNESS DISTRIBUTION 86 7. CROSS-SECTION SHAPE PARAMETRIZATION FOR PERIODIC B-SPLINES 96 7.1 PRELIMINARIES IN B-SPLINE CONTROL GRID ESTIMATION 97 7.2 CROSS-SECTION EXTRACTION OF 2D IMAGES 101 7.3 TENSOR SPLINE PARAMETRIZATION WITH MOMENTS OF AREA 105 7.4 B-SPLINE PARAMETRIZATION WITH MOMENTS OF AREA GUIDED CONVOLUTIONAL NEURAL NETWORK 110 8. FULLY AUTOMATED COMPLIANCE OPTIMIZATION AND CURVE-SKELETON PARAMETRIZATION FOR A CPU HEAT SINK WITH SIZE CONTROL FOR SLM 115 8.1 AUTOMATED 1D THERMAL COMPLIANCE MINIMIZATION, CONSTRAINED SURFACE RECONSTRUCTION AND ADDITIVE MANUFACTURING 118 8.2 AUTOMATED 2D THERMAL COMPLIANCE MINIMIZATION, CONSTRAINT SURFACE RECONSTRUCTION AND ADDITIVE MANUFACTURING 120 8.3 USING THE HEAT SINK PROTOTYPES COOLING A CPU 123 9. CONCLUSION 127 10. OUTLOOK 131 LITERATURE 133 APPENDIX 147 A PREVIOUS STUDIES 147 B CROSS-SECTION PROPERTIES 149 C CASE STUDIES FOR THE CROSS-SECTION PARAMETRIZATION 155 D EXPERIMENTAL SETUP 15

A survey on personal computer applications in industrial design process

Thesis (Master)--Izmir Institute of Technology, Industrial Design, Izmir, 1999Includes bibliographical references (leaves: 157-162)Text in English, Abstract: Turkish and Englishxii, 194 leavesIn this thesis, computer aided design systems are studied from the industrial designer's point of view. The study includes industrial design processes, computer aided design systems and the integration aspects.The technical issues are priorly studied, including current hardware and software technologies. The pure technical concepts are tried to be supported with real-world examples and graphics. Several important design software are examined, whether by personal practice or by literature research, depending on the availability of the software.Finally, the thesis include a case study, a 17" LCD computer monitor designed with a set of graphic programs including two-dimensional and three-dimensional packages.Keywords: Computers, industrial design methods, design software, computer aided design

Virtual sculpting : an investigation of directly manipulated free-form deformation in a virtual environment

This thesis presents a Virtual Sculpting system, which addresses the problem of Free-Form Solid Modelling. The disparate elements of a Polygon-Mesh representation, a Directly Manipulated Free-Form Deformation sculpting tool, and a Virtual Environment are drawn into a cohesive whole under the mantle of a clay-sculpting metaphor. This enables a user to mould and manipulate a synthetic solid interactively as if it were composed of malleable clay. The focus of this study is on the interactivity, intuitivity and versatility of such a system. To this end, a range of improvements is investigated which significantly enhances the efficiency and correctness of Directly Manipulated Free-Form Deformation, both separately and as a seamless component of the Virtual Sculpting system

Fab + Craft: Synthesis of Maker, Machine, Material

Within contemporary architecture a fundamental disjunction exists between design and building facilitated by the use of advanced computational methods, and the relationship between form, material, and maker. The making of buildings demands an expertise that is familiar with the physical and involves a level of skill that many designers cannot claim to fully possess or practice. This doctorate project presents a study of a design-through-making methodology that incorporates craft with the material exploration of sandwich panels, digital technology and fabrication in the process of ‘making’ architecture. A focus is placed on the development of a specific design intent through the manipulation of materials, using skills and techniques guided by the practiced hand. This interaction between technology, material, and the designer-maker referred to as “fab+craft” creates a narrative that allows for the physical translation of ideas into the built environment