Commercial Computer-aided Design Research Articles

Integrating Computer Vision and CAD for Precise Dimension Extraction and 3D Solid Model Regeneration for Enhanced Quality Assurance

This paper focuses on the development of an integrated system that can rapidly and accurately extract the geometrical dimensions of a physical object assisted by a robotic hand and generate a 3D model of an object in a popular commercial Computer-Aided Design (CAD) software using computer vision. Two sets of experiments were performed: one with a simple cubical object and the other with a more complex geometry that needed photogrammetry to redraw it in the CAD system. For the accurate positioning of the object, a robotic hand was used. An Internet of Things (IoT) based camera unit was used for capturing the image and wirelessly transmitting it over the network. Computer vision algorithms such as GrabCut, Canny edge detector, and morphological operations were used for extracting border points of the input. The coordinates of the vertices of the solids were then transferred to the Computer-Aided Design (CAD) software via a macro to clean and generate the border curve. Finally, a 3D solid model is generated by linear extrusion based on the curve generated in CATIA. The results showed excellent regeneration of an object. This research makes two significant contributions. Firstly, it introduces an integrated system designed to achieve precise dimension extraction from solid objects. Secondly, it presents a method for regenerating intricate 3D solids with consistent cross-sections. The proposed system holds promise for a wide range of applications, including automatic 3D object reconstruction and quality assurance of 3D-printed objects, addressing potential defects arising from factors such as shrinkage and calibration, all with minimal user intervention.

User Perspectives on Branching in Computer-Aided Design

Branching is a feature of distributed version control systems that facilitates the "divide and conquer" strategy present in complex and collaborative work domains. Branching has revolutionized modern software development and has the potential to similarly transform hardware product development via CAD (computer-aided design). Yet, contrasting with its status in software, branching as a feature of commercial CAD systems is in its infancy, and little research exists to investigate its use in the digital design and development of physical products. To address this knowledge gap, in this paper, we mine and analyze 719 user-generated posts from online CAD forums to qualitatively study designers' intentions for and preliminary use of branching in CAD. Our work contributes a taxonomy of CAD branching use cases, an identification of deficiencies of existing branching capabilities in CAD, and a discussion of the untapped potential of CAD branching to support a new paradigm of collaborative mechanical design. The insights gained from this study may help CAD tool developers address design shortcomings in CAD branching tools and assist CAD practitioners by raising their awareness of CAD branching to improve design efficiency and collaborative workflows in hardware development teams.

Design and Implementation of a Three-Dimensional CAD Graphics Support Platform for Pumps Based on Open CASCADE

In the pump industry, designers commonly utilize mainstream three-dimensional computer-aided design (CAD) software (Unigraphics NX 12.0 and SolidWorks 2023). However, these CAD packages are generic and not optimized for the specific requirements of the pump industry. This leads to a lack of flexibility and increased complexity in their usage, as well as higher computational demands, resulting in elevated learning and operational costs. Additionally, there are concerns about potential information leaks and software restrictions. In this paper, we studied the organization architecture of commercial three-dimensional CAD software, and compared and analyzed the geometric kernels and rendering engines of mainstream three-dimensional software. Using the Open CASCADE geometric kernel and OpenSceneGraph rendering engine, together with the Visual Studio 2021 development environment and Qt interface library, we developed an autonomous copyright three-dimensional CAD graphics support platform for pumps. Based on the three-dimensional platform, we tested the commonly used graphics elements and basic algorithms required for pump modeling, and successfully designed and modeled the impeller and volute casing of a centrifugal pump. Through computational simulations and experimental verifications, we demonstrated that the accuracy and precision of the pump model designed on this platform meets the design requirements, indicating that this platform has practical pump design and modeling capabilities. Compared to commercial three-dimensional CAD software, this platform exhibits superior flexibility and interactivity in three-dimensional modeling that is specifically tailored for pump products. Consequently, it fully satisfies the needs for three-dimensional parameterized modeling and visualization of pumps.

An automated topology optimization interpreter that generates space frames

This paper presents the methodology and theoretical foundation of topology optimization (TO) Results Spaceframe Interpreter, an automatic TO results interpreter that generates a closely associated space frame consisting of welded structural tubing or rectangular bars. TO is a computational technique that uses a finite element (FE) formulation to identify the most weight-efficient structure within a design domain. Density-based TO results in structures that take organic forms and is usually a tedious and cumbersome process to generate a computer-aided-design (CAD) model to manufacture through conventional techniques. The optimal topology frequently resembles a space frame, which is well-known as being a rigid, lightweight structure. The methodology of the TO results interpreter leverages several techniques from volumetric image processing and has four primary processes. First, the results are obtained from commercial FE/TO software and mapped into a cubic grid of voxels. Second, junction locations are extracted and member connectivity that represents a frame is identified. Third, a sizing optimization is incorporated to determine appropriate sectional dimensions of the circular or rectangular space frame members. Fourth, the optimized space frame geometry is imported into a CAD design tool to automatically create a design model. The logic and are implemented within the frame extraction processes. The automated TO interpreter is designed to interact with commercial FE analysis and CAD systems. The interpreter is demonstrated on various spatial examples including aerospace and automotive applications. In each case, the welded space frame closely resembles the TO result, with nearly equivalent stiffness and mass.

A decision-support method for multi-parameter editing of parametric CAD models

Parametric modeling is a computer-aided design (CAD) paradigm where a design can be created by defining geometric constraints with parameters. In design change as well as design optimization, the design is often edited by modifying the values of relevant parameters. Without guidance on allowable parameter ranges that can guarantee the intrinsic solvability of the geometric constraint system, the user could assign improper values to the model’s parameters, which would further lead to a failure in model updating. However, current commercial CAD systems provide little support on such guidance. Existing methods, though able to compute allowable ranges for individual parameters, face difficulties in handling multi-parameter situations. To solve this problem, a systematic method is proposed, supporting decision-making in multi-parameter model editing by computing allowable parameter ranges. In the method, a set of variable parameters from the geometric constraint system are first selected by the user; these variable parameters are to be sequentially edited within several editing operations. Before each editing operation, 1D allowable ranges of the variable parameters are computed. By editing parameter values within the provided ranges, the solvability of the geometric constraint system can be guaranteed. The effectiveness and efficiency of the proposed approach is verified by several experimental results.

Applying conditional optimization to determine the allowable loads on flexurally rigid threads

Objective. Development of a methodology for determining the allowable loads on existing structural elements, the design model of which is a flexural-rigid thread, based on the requirements of strength and rigidity due to the changed operating conditions of structures.Method. This study is based on mathematical modeling of the problem of conditional optimization. The objective function is the total potential energy of deformation of a thread with some flexural rigidity. In this case, restrictions are imposed on strength, rigidity, and the condition of continuity of deformations. At the same time, to achieve this goal, the provisions of the strength of materials, as well as the apparatus of integral and differential calculation of functions of one or more variables, were used.Result. An assessment of the adequacy of the results obtained using the developed methodology was carried out. A numerical experiment was performed to determine the value of the allowable uniformly distributed load and the corresponding distribution of stresses and strains along the length of a thread of finite stiffness with given physical and geometric parameters. It has been established that the discrepancies in the values of the results obtained using the proposed modeling technology and the commercial computer-aided design and calculation system LIRA 10.8, implemented on the generally recognized finite element method, are no more than 5%.Conclusion. The developed technique allows setting and solving problems of determining the ultimate loads on flexural-rigid threads, based on the allowable stresses and strains, in contrast to existing commercial computer simulation systems that solve exclusively direct problems of determining the stress-strain state of various types of structures. It can be used at the stage of inspection of large-span coatings in the reconstruction of public buildings and engineering structures.

Feature extraction for margin lines using region growing with a dynamic weight function in a one-point bidirectional path search

Abstract A margin line, defined as the boundary curve of the contact area between a prepared tooth and a dental restoration, considerably influences the end shape of the dental restoration design. Most studies that have extracted margin lines from mesh models representing prepared teeth have faced convergence problems in the path search and therefore pose the inconvenience of specifying multiple input points as intermediate goal points. To overcome these problems, in this study, we propose a bidirectional path-search algorithm using a single input point. First, the algorithm classifies all nodes in a mesh model into a margin or fuzzy region to increase search efficiency. Then, the search starts from one point and proceeds on two paths in opposite directions, using the current node of the opposite path as the temporary goal of the currently searched path. During the search, a dynamic evaluation function that varies weights according to the region type is employed to improve the path convergence. Finally, to increase the practicality of the algorithm, the jagged initial margin line is converted into a smooth spline curve using an energy-minimization function specialized for margin lines. To evaluate the proposed algorithm, margin lines extracted from various types of prepared teeth are demonstrated and compared with those created using some relevant previous works and a commercial dental computer-aided design (CAD) system. The comparison verified that accurate margin lines could be calculated with only one input point using the proposed algorithm. Moreover, the proposed algorithm showed better performance for crown and inlay/only experimental models compared with a commercial dental CAD system under the same conditions.

G-code generation in a NURBS workflow for precise additive manufacturing

Purpose Non-uniform rational B-splines (NURBSs) are the de facto standard for representing objects in computer-aided design (CAD). The purpose of this paper is to discuss how to stick to this standard in all phases of the additive manufacturing (AM) workflow, from the CAD object to the final G-code, bypassing unnecessary polygonal approximations. Design/methodology/approach The authors use a commercial CAD system (Rhino3D along with its programming environment Grasshopper) for direct slicing of the model, offset generation and trimming. Circular arcs are represented as quadratic NURBSs and free-form geometry as quadratic or cubic polynomial B-splines. Therefore, circular arcs are directly expressible as G2/G3 G-code commands, whereas free-form paths are rewritten as a succession of cubic Bézier curves, thereby admitting exact translation into G5 commands, available in firmware for AM controllers, such as Marlin. Findings Experimental results of this paper confirm a considerable improvement in quality over the standard AM workflow, consisting of an initial polygonization of the object (e.g. via standard tessellation language), slicing this polygonal approximation, offsetting the polygonal sections and, finally, generating G-code made up of polyline trajectories (G1 commands). Originality/value A streamlined AM workflow is obtained, with a seamless transfer from the initial CAD description to the final G-code. By adhering to the NURBS standard at all steps, the authors avoid multiple representations and associated errors resulting from approximations.

Calculation method of hosiery knitting parameters based on three-dimensional mesh sampling

Custom socks, such as medical compression socks and hiking socks, are precisely designed and knitted according to the user's foot shape. However, developing styles of custom socks with commercial computer-aided design software requires workers to manually calculate the knitting parameters, and repeatedly adjust the knitting parameters through sample-making to meet the design requirements. We present a method to optimize the manual calculation and adjustment process of knitting parameters by using graphics technology. Our method converts a sock mesh model created by conventional modeling software into knitting parameters. Hosiery machines are able to knit socks with the same dimensions as the mesh based on the output parameters. Specifically, given user-defined top and toe markers on an input mesh, our system runs a sampling procedure over this mesh to gradually generate a knitting path that contains shape and dimension features of the mesh, and transforms the knitting path into knitting parameters for machine knitting. We demonstrated the feasibility of our method by knitting on a computerized hosiery machine. Filling the knitted socks with a soft foam model, we found that the knitted socks fit roughly well with the mesh surface, and the dimensional gap between the input mesh and the knitted socks (relaxed state) in several positions was below 4.90%.

Generalized Bezier components and successive component refinement using moving morphable components

This paper demonstrates developments that introduce generalized Bezier components in the Moving Morphable Components (MMC) optimization framework. Methods of enhancing the parameterization of the components to provide the opportunity for a better optimum, than can be achieved using existing approaches, are also described. The use of control points and Bezier curves for representing structural components provides both additional flexibility in the shape and a parameterization that complies with extrude and swept feature-based templates available in commercial computer-aided design (CAD) packages. Methods of representing these structural components, calculating analytical derivatives, and numerical examples demonstrating their integration in the MMC framework, are presented for a series of author-derived and literature problems. A successive refinement technique demonstrates how the additional flexibility in the structural components enables progressive improvement in the objective function. For the examined problems, increasing the design variables per component (from 5 to 15) resulted in solutions with 6% to 36% reduction in compliance. This improvement was achieved without increasing the number of components in the design space.

Combining 3D-Printing and Electrospinning to Manufacture Biomimetic Heart Valve Leaflets.

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds with adjustable properties. The aim of this study was to create multilayered scaffolds mimicking the architectural fiber characteristics of human heart valve leaflets using conductive 3D-printed collectors. Models of aortic valve cusps were created using commercial computer-aided design (CAD) software. Conductive polylactic acid was used to fabricate 3D-printed leaflet templates. These cusp negatives were integrated into a specifically designed, rotating electrospinning mandrel. Three layers of polyurethane were spun onto the collector, mimicking the fiber orientation of human heart valves. Surface and fiber structure was assessed with a scanning electron microscope (SEM). The application of fluorescent dye additionally permitted the microscopic visualization of the multilayered fiber structure. Tensile testing was performed to assess the biomechanical properties of the scaffolds. 3D-printing of essential parts for the electrospinning rig was possible in a short time for a low budget. The aortic valve cusps created following this protocol were three-layered, with a fiber diameter of 4.1 ± 1.6 µm. SEM imaging revealed an even distribution of fibers. Fluorescence microscopy revealed individual layers with differently aligned fibers, with each layer precisely reaching the desired fiber configuration. The produced scaffolds showed high tensile strength, especially along the direction of alignment. The printing files for the different collectors are available as Supplemental File 1, Supplemental File 2, Supplemental File 3, Supplemental File 4, and Supplemental File 5. With a highly specialized setup and workflow protocol, it is possible to mimic tissues with complex fiber structures over multiple layers. Spinning directly on 3D-printed collectors creates considerable flexibility in manufacturing 3D shapes at low production costs.

Combining 3D-Printing and Electrospinning to Manufacture Biomimetic Heart Valve Leaflets

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds with adjustable properties. The aim of this study was to create multilayered scaffolds mimicking the architectural fiber characteristics of human heart valve leaflets using conductive 3D-printed collectors. Models of aortic valve cusps were created using commercial computer-aided design (CAD) software. Conductive polylactic acid was used to fabricate 3D-printed leaflet templates. These cusp negatives were integrated into a specifically designed, rotating electrospinning mandrel. Three layers of polyurethane were spun onto the collector, mimicking the fiber orientation of human heart valves. Surface and fiber structure was assessed with a scanning electron microscope (SEM). The application of fluorescent dye additionally permitted the microscopic visualization of the multilayered fiber structure. Tensile testing was performed to assess the biomechanical properties of the scaffolds. 3D-printing of essential parts for the electrospinning rig was possible in a short time for a low budget. The aortic valve cusps created following this protocol were three-layered, with a fiber diameter of 4.1 ± 1.6 µm. SEM imaging revealed an even distribution of fibers. Fluorescence microscopy revealed individual layers with differently aligned fibers, with each layer precisely reaching the desired fiber configuration. The produced scaffolds showed high tensile strength, especially along the direction of alignment. The printing files for the different collectors are available as Supplemental File 1, Supplemental File 2, Supplemental File 3, Supplemental File 4, and Supplemental File 5. With a highly specialized setup and workflow protocol, it is possible to mimic tissues with complex fiber structures over multiple layers. Spinning directly on 3D-printed collectors creates considerable flexibility in manufacturing 3D shapes at low production costs.

FLatt Pack: A research-focussed lattice design program

Lattice structures are an important aspect of design for additive manufacturing (DfAM). They enable significant component light-weighting and the tailoring of a wide range of physical responses; mechanical, thermal, acoustic, etc. In turn, lattice design relies on fundamental research to uncover useful structure-property relationships, such as the influence of cell geometry and volume fraction. A number of commercial computer-aided-design (CAD) programs exist that offer lattice generation, but these tend to prioritise product design. This paper describes the FLatt Pack program (or Functional Lattice Package), which was created to address the paucity of research-focussed lattice design software. It possesses a number of features with this in mind, including; (i) it is free to use for research, (ii) it is standalone software with minimal, and also free, dependencies, and (iii) it undergoes frequent and rapid development based on state of the art lattice information and modelling methods. FLatt Pack includes twenty-three lattice cell types covering a broad range of pore connectivity, structural anisotropy, and surface area; a clear GUI presenting the lattice design stages in a sequential manner; and the option to export designs in appropriate formats for AM and finite element (FE) simulation. The program also features conformal lattice generation in arbitrary shapes, arbitrary volume fraction grading, and resource-efficient computation through an adaptive spatial resolution based on the user’s design choices. The most recent version of FLatt Pack is freely available at: www.github.com/ian27ax/FLatt_Pack_dist .

AutoMate

Assembly modeling is a core task of computer aided design (CAD), comprising around one third of the work in a CAD workflow. Optimizing this process therefore represents a huge opportunity in the design of a CAD system, but current research of assembly based modeling is not directly applicable to modern CAD systems because it eschews the dominant data structure of modern CAD: parametric boundary representations (BREPs). CAD assembly modeling defines assemblies as a system of pairwise constraints, called mates , between parts, which are defined relative to BREP topology rather than in world coordinates common to existing work. We propose SB-GCN, a representation learning scheme on BREPs that retains the topological structure of parts, and use these learned representations to predict CAD type mates. To train our system, we compiled the first large scale dataset of BREP CAD assemblies, which we are releasing along with benchmark mate prediction tasks. Finally, we demonstrate the compatibility of our model with an existing commercial CAD system by building a tool that assists users in mate creation by suggesting mate completions, with 72.2% accuracy.

Simulation studies on electrical characteristics of silicon nanowire feedback field-effect transistors with interface trap charges

In this study, we examine the electrical characteristics of silicon nanowire feedback field-effect transistors (FBFETs) with interface trap charges between the channel and gate oxide. The band diagram, I–V characteristics, memory window, and operation were analyzed using a commercial technology computer-aided design simulation. In an n-channel FBFET, the memory window narrows (widens) from 5.47 to 3.59 V (9.24 V), as the density of the positive (negative) trap charges increases. In contrast, in the p-channel FBFET, the memory window widens (narrows) from 5.38 to 7.38 V (4.18 V), as the density of the positive (negative) trap charges increases. Moreover, we investigate the difference in the output drain current based on the interface trap charges during the memory operation.

Parametric Hull Design with Rational Bézier Curves and Estimation of Performances

In this paper, a tool able to support the sailing yacht designer during the early stage of the design process has been developed. Cubic Rational Bézier curves have been selected to describe the main curves defining the hull of a sailing yacht. The adopted approach is based upon the definition of a set of parameters, say the length of waterline, the beam of the waterline, canoe body draft and some dimensionless coefficients according to the traditional way of the yacht designer. Some geometrical constraints imposed on the curves (e.g., continuity, endpoint angles, curvature) have been conceived aimed to avoid unreasonable shapes. These curves can be imported into any commercial Computer Aided Design (CAD) software and used as a frame to fit with a surface. The resistance of the hull can be calculated and plotted in order to have a real time estimation of the performances. The algorithm and the related Graphical User Interface (GUI) have been written in Visual Basic for Excel. To test the usability and the precision of the tool, two existing sailboats with different characteristics have been successfully replicated and a new design, taking advantages of both the hulls, has been developed. The new design shows good performances in terms of resistance values in a wide range of Froude numbers with respect to the original hulls.

Computer-Aided Sketching: Incorporating the Locus to Improve the Three-Dimensional Geometric Design

This article presents evidence of the convenience of implementing the geometric places of the plane into commercial computer-aided design (CAD) software as auxiliary tools in the computer-aided sketching process. Additionally, the research considers the possibility of adding several intuitive spatial geometric places to improve the efficiency of the three-dimensional geometric design. For demonstrative purposes, four examples are presented. A two-dimensional figure positioned on the flat face of an object shows the significant improvement over tools currently available in commercial CAD software, both vector and parametric: it is more intuitive and does not require the designer to execute as many operations. Two more complex three-dimensional examples are presented to show how the use of spatial geometric places, implemented as CAD software functions, would be an effective and highly intuitive tool. Using these functions produces auxiliary curved surfaces with points whose notable features are a significant innovation. A final example provided solves a geometric place problem using own software designed for this purpose. The proposal to incorporate geometric places into CAD software would lead to a significant improvement in the field of computational geometry. Consequently, the incorporation of geometric places into CAD software could increase technical-design productivity by eliminating some intermediate operations, such as symmetry, among others, and improving the geometry training of less skilled users.

Feature-based translation of CAD models with macro-parametric approach: issues of feature mapping, persistent naming, and constraint translation

Abstract Feature-based translation of computer-aided design (CAD) models allows designers to preserve the modeling history as a series of modeling operations. Modeling operations or features contain information that is required to modify CAD models to create different variants. Conventional formats, including the standard for the exchange of product model data or the initial graphics exchange specification, cannot preserve design intent and only geometric models can be exchanged. As a result, it is not possible to modify these models after their exchange. Macro-parametric approach (MPA) is a method for exchanging feature-based CAD models among heterogeneous CAD systems. TransCAD, a CAD system for inter-CAD translation, is based on this approach. Translators based on MPA were implemented and tested for exchange between two commercial CAD systems. The issues found during the test rallies are reported and analyzed in this work. MPA can be further extended to remaining features and constraints for exchange between commercial CAD systems.

The Development Of Sensing Architecture For Inferior Alveolar Nerve Block Clinical Simulator Kit

This paper presents the development of sensing architecture for Inferior Alveolar Nerve Block (IANB) clinical simulator kit. The ultimate objective of this project is to emulate the environment of anaesthesia administration on an IANB which considers the integration of 3D printing technology and internet of things (IoT) concept. The 3D model of a lower jaw is obtained through Digital Imaging and Communications in Medicine (DICOM) data via dental Cone Beam Computed Tomography (CBCT) on a patient. The obtained model is further refined to facilitate the integration of the electronic circuit by utilization of a commercial computer-aided design (CAD) software package. The printed model is then integrated with a sensing mechanism to provide real-time data feedback during simulation of local anaesthesia administration training. From the validation results, it shows that the prototype able to give real-time data feedback and display the results on the user interface.

Auto-assessment tools for mechanical computer aided design education

Traditionally Computer Aided Design (CAD) courses have been carried out in computer classrooms requiring great amount of teaching personnel. Assessment of students' modeling exercises has been both time consuming and error prone. Utilization of the teaching resources could clearly benefit from online auto-assessment. The auto-assessment tools are widely in use in programming and language courses, but suitable tools for assessing 3D models used in CAD are lacking. This paper presents two new online auto-assessment tools to support the development of both command (“what steps are needed to create this shape?”) and strategic (“how should I model this shape?”) knowledge while learning CAD. The first tool is based on neutral file format (in this case STEP) and can recognize surface differences between student's model and reference model. This tool can assess student's skill to create certain predefined shape (i.e. command knowledge). The second auto-assessment tool utilizes commercial CAD software's API (Application Programming Interface) to test how student's model behaves when modeling parameters are changed. This tool assess student's capabilities to build and design a CAD model's design intent (i.e. strategic knowledge). Developed tools were tested on three mechanical engineering courses. This paper presents both the tools and the feedback received from the students and teachers. Overall, the auto-assessment tools functioned well and feedback from both students and teachers were positive. The most appreciated tool functionality was time and place independent submission and assessment of exercise works. These new tools able focusing teachers' workload from checking the basic exercises to guiding the learning process.