CAD Format Research Articles

Optimization of laser micro milling of alumina ceramic using radial basis functions and MOGA-II

Laser milling provides an efficient method for the fabrication of micro-featured products for a wide range of materials including ceramics by directly importing the design data in various CAD formats. Despite the good process capabilities, research on micro milling for structural ceramics has been given less attention as compared to micro drilling and turning. In addition, most of the studies are limited to factorial analysis. Optimization in terms of multiple objectives and constraints are rare. This paper considers the analysis and optimization of Nd:YAG laser micro milling of alumina ceramic using smooth spline analysis of variance (ANOVA), radial basis functions (RBF), and a multi-objective genetic algorithm (MOGA-II). MOGA-II uses a new smart multi-search elitism operator. It has been found that low surface roughness for micro-milled alumina ceramic is obtained with low frequencies, low pulse overlaps, and moderate intensities. On the other hand, high material removal rates are associated with high laser beam intensities. Optimized solutions are characterized by low and moderate frequencies, high intensities, and medium pulse overlaps.

A boundary element and level set based topology optimisation using sensitivity analysis

The structural topology optimisation method presented in this paper is based on the boundary element method, level set method and shape sensitivity analysis for two-dimensional linear elastic problems. The proposed method automatically nucleates holes within the design domain during the optimisation process using a topological derivative based hole insertion criterion. The level set method is used to provide an implicit description of the structural geometry, which is capable of automatically handling topological changes, i.e. holes merging with each other or with the boundary. During the optimisation process non-uniform rational b-splines are fitted through the zero level set contours, which links an implicit geometry representation to its structural model. In addition, this provides an optimal design in standard CAD format, and without intermediate material densities, which can be directly used in other design processes. The proposed optimisation method is tested against different benchmark examples and the optimal geometries generated are in close agreement those available in the literature of topology optimisation.

A similarity-based reuse system for injection mold design in automotive interior industry

Injection mold design of automotive interior is knowledge-intensive and time-consuming; therefore, it is important to reuse previous design instead of designing from scratch. This work proposed a systematic similarity-based approach to reuse design resources. With transformation of native CAD format to STEP for global and partial retrieval, the process of reuse constitutes five steps: (i) initial retrieval for candidates parts, (ii) precise retrieval for similar case based on typical surface retrieval, (iii) adaptation of similar case such as mold base, (iv) reuse-forming mechanism based on partial retrieval of detailed feature similarity, and (v) instance detection and automatic locating of forming mechanism based on partial similarity. While hierarchical representation of CAD models proposed in our previous work serves as the kernel of retrieval, parametric assembly modeling and visual based automation testing are integrated in the reuse process of mold base in step (iii). A case study of the proposed reuse approach is provided, and feedback from automotive interior industry validated its feasibility.

組織設計事務所における設計分業体制に関する基本的考察

This paper focuses on the mechanism of task distribution in a design process. US projects are comparatively researched to clarify the uniqueness of task distribution in Japanese projects. In every project, a design organization is composed with technically specialized design teams, such as architects, structural engineers, mechanical engineers, electrical engineers, plumbing engineers, and other consultants (Fig. 2). The design teams divide the design tasks based on their specialty. Among the design teams, an architectural design team is staffed with architects. Architects divide their design tasks based on their specialty as well. These task distributions both in a design organization and an architectural design team are investigated. Draftsman and interns are eliminated from the survey, due to their non-certified professional status. Projects in the both countries are investigated to clarify the task distribution among technically specialized design teams. Ten US Design-Bid-Build projects are researched as a case study of design organization (Table1). Many consultants are called upon the project based on the highly segmented technical specialization. In architectural design, specialized professions such as Spec Writer or Building Permit Experditer only been found in the US practices. In engineering design, plumbing engineers are recognized in all of the US projects, whereas, the plumbing design is usually taken care by mechanical engineers in Japan. Standardization of the CAD format helps fluent information exchange for task distribution among US professionals. Ten Japanese Design-Bid Build projects are surveyed as a comparison (Table2). Segmentation of the technical specialization is less obvious. However, technically specialized fabricators and suppliers offer their product design information free of charge, under the notion of “Design Assistance (sekkei kyoryoku), ” in the hopes of their products will be specified and installed in the construction. Projects in the both countries are further investigated to clarify different exercise of the task distribution in the architectural design team. In the US, some architects only participate the initial part of the design process such as SD and DD phases, and the others involve in the latter part of the design process such as DD and CD phases (Fig. 4). The distribution of the design tasks is recognized in the design process. Standardization of CAD format may help to accelerate information sharing among architects. In Japan, architects tend not to divide their design tasks. They are inclined to participate the project from the beginning of the design phase to the end of the construction administration phase (Fig. 5).

А System for Input of 3D Objects into Computing Environment

This paper proposes an approach for design and implementation of automated 3D scanner used for input of mechanical 3D objects into computing environment. The presented model of 3D scanner is based on kinematic diagram of positioning system with 5 degree of freedom – 3 linear and 2 rotational, each driven by servo motors. For distance measuring is used laser scanning head with rotational triangulation. The paper describes also algorithms for functional control of the scanning process, obtaining of point cloud, object reconstruction and export to standard CAD format. Keywords

Segmentation of Indoor Mapping Point Clouds Applied to Crime Scenes Reconstruction

Data acquisition in forensics science must be performed in a fast and an efficient way, so that the data acquired is maximized at the same time that disturbance and time on the scene are minimized. For this reason, the use of indoor mapping systems appears as a key solution, in contrast with static systems, either laser or photogrammetry based, in which representing big and complex scenes requires acquisition from a high number of positions, and long-time dedication for data processing. This paper presents a methodology for the segmentation of point clouds acquired with a mobile indoor mapping system, and their conversion to 3-D models in CAD format, based on parameterized geometric elements from the scene. This way, all the information required in forensic sciences is stored in an adequate digital format, enabling its availability in the future, and minimizing time dedication in both data acquisition and processing steps.

Web-based laboratory for collaborative and concurrent CAD designing, assembling, and practical exercising on distance

Original scientific paper Collaborative CAD of distant modelling is a today’s necessity for realization in a timely manner. This need arises even within educational institutions, where investments in the development of technologies to support collaborative distance learning are still trivial. Most CAD programs used in engineering have modules for collaboration. However, these solutions are expensive, especially for educational institutions that have a large number of students. The mentioned modules generally work within a specific CAD platform and support import and export of a limited number of CAD formats. In this paper, we present an open-source solution that overcomes these problems. It implements practical work at a distance by combining most commonly used CAD platforms in engineering. In this paper, we describe how to use virtual laboratory for rapid designing through execution of practical exercises. The architecture of the proposed solution, the modelling of the laboratory and methods for creating its functions are described. Also, given is a tangible example of collaborative aircraft assembly between distant students, with parts modelled in different CAD packages, and the usability of labs presented through prototype builds on 3D printer and the final test in the wind tunnel. Qualitative and quantitative evaluations were conducted. Conclusions set the direction of the future development using various technologies for building virtual assembly laboratory.

Prediction of pedestrians routes within a built environment in normal conditions

Modelling and prediction of pedestrian routing behaviours within known built environments has recently attracted the attention of researchers across multiple disciplines, owing to the growing demand on urban resources and requirements for efficient use of public facilities. This study presents an investigation into pedestrians’ routing behaviours within an indoor environment under normal, non-panic situations. A network-based method using constrained Delaunay triangulation is adopted, and a utility-based model employing dynamic programming is developed. The main contribution of this study is the formulation of an appropriate utility function that allows an effective application of dynamic programming to predict a series of consecutive waypoints within a built environment. The aim is to generate accurate sequence waypoints for the pedestrian walking path using only structural definitions of the environment as defined in a standard CAD format. The simulation results are benchmarked against those from the A∗ algorithm, and the outcome positively indicates the usefulness of the proposed method in predicting pedestrians’ route selection activities.

A flexible and extensible approach to automated CAD/CAM format classification

There are hundreds of distinct 3D, CAD and engineering file formats. As engineering design and analysis has become increasingly digital, the proliferation of file formats has created many problems for data preservation, data exchange, and interoperability. In some situations, physical file objects exist on legacy media and must be identified and interpreted for reuse. In other cases, file objects may have varying representational expressiveness.We introduce the problem of automated file recognition and classification in emerging digital engineering environments, where all design, manufacturing and production activities are “born digital.” The result is that massive quantities and varieties of data objects are created during the product lifecycle.This paper presents an approach to automated identification of engineering file formats. This work operates independent of any modeling tools and can identify families of related file objects as well as variations in versions. This problem is challenging as it cannot assume any a priori knowledge about the nature of the physical file object. Applications for these methods include support for a number of emerging applications in areas such as forensic analysis, data translation, as well as digital curation and long-term data management.

Extra Dimensions: 3D in PDF Documentation

Experimental science is replete with multi-dimensional information which is often poorly represented by the two dimensions of presentation slides and print media. Past efforts to disseminate such information to a wider audience have failed for a number of reasons, including a lack of standards which are easy to implement and have broad support. Adobe's Portable Document Format (PDF) has in recent years become the de facto standard for secure, dependable electronic information exchange. It has done so by creating an open format, providing support for multiple platforms and being reliable and extensible. By providing support for the ECMA standard Universal 3D (U3D) and the ISO PRC file format in its free Adobe Reader software, Adobe has made it easy to distribute and interact with 3D content. Until recently, Adobe's Acrobat software was also capable of incorporating 3D content into PDF files from a variety of 3D file formats, including proprietary CAD formats. However, this functionality is no longer available in Acrobat X, having been spun off to a separate company. Incorporating 3D content now requires the additional purchase of a separate plug-in. In this talk we present alternatives based on open source libraries which allow the programmatic creation of 3D content in PDF format. While not providing the same level of access to CAD files as the commercial software, it does provide physicists with an alternative path to incorporate 3D content into PDF files from such disparate applications as detector geometries from Geant4, 3D data sets, mathematical surfaces or tesselated volumes.

A Design Methodology for Reverse Engineering Integrated with Anatomical CAD

In the conventional Reverse Engineering (RE), the first step is modeling industrial components from point cloud to parametric CAD model, and then the necessary design will be operated in a parametric CAD environment. Therefore the reverse engineering process is very time-consuming and error-prone. The Anatomical CAD means allowing the common Computer Aided Design operations on 3D anatomical data. 3-matic is a software package which equipped with an Anatomical Reverse Engineering module, with this module we can do the design operations on anatomical data. In this paper, we propose a new design methodology integrated with Anatomical CAD, which we can eliminate the first step of reverse engineering of the scanned data to a CAD format, save the time and work more accurately.

Digital Modeling of End-Mill Cutting Tools for FEM Applications from the Active Cutting Contour

A very current technique in the research field of machining by material removal is the use of simulations using the Finite Element Method (FEM). Nevertheless, and although is widely used in processes that allows approximations to orthogonal cutting, such as shaping, is scarcely used in more complexes processes, such as milling. This fact is due principally to the complex geometry of the cutting tools in these processes, and the need to realize the studi es in an oblique cutting configuration. This paper shows a methodology for the geometrical characterization of commercial end-mill cutting tools, by the extraction of the cutting tool contour, making use of optical metrology, and using this geometry to model the active cutting zone with a 3D CAD software. This model is easily exportable to different CAD formats, such as IGES or STEP, and importable from FEM software, where is possible to study the behavior in service of the same ones.

Study on the Visual Prediction and Analysis Method of Mining Subsidence

In view of actual conditions that AutoCAD is widely used in coal mines in China, the concrete method based on CASS software is intruduced, which can realize the visual prediction and analysis of mining subsidence. Because CASS software has been developed based on AutoCAD, when the digital mining map of CAD format is used, the switchover of data format is not required, and the input, output and edit of the digital mining map is very convenient. The displacement and distortion information of mining subsidence forecast can be represented in the digital mining map by means of the visual graph, which can easily analyze and evaluate mining subsidence. Using the visual method, the efficiency and accuracy of technical decision can be enhanced, and it has practical significance for the mine planning and design and the prevention and control of mining subsidence.

Digital Image Capture and Rapid Prototyping of the Maxillofacial Defect

In order to restore an extraoral maxillofacial defect, a moulage impression is commonly made with traditional impression materials. This technique has some disadvantages, including distortion of the site due to the weight of the impression material, changes in tissue location with modifications of the patient position, and the length of time and discomfort for the patient due to the impression procedure and materials used. The use of the commercially available 3dMDface™ System creates 3D images of soft tissues to form an anatomically accurate 3D surface image. Rapid prototyping converts the virtual designs from the 3dMDface™ System into a physical model by converting the data to a ZPrint (ZPR) CAD format file and a stereolithography (STL) file. The data, in conjunction with a Zprinter(®) 450 or a Stereolithography Apparatus (SLA), can be used to fabricate a model for prosthesis fabrication, without the disadvantages of the standard moulage technique. This article reviews this technique and how it can be applied to maxillofacial prosthetics.

New Polar Instruments PCB repair system supports most popular CAD formats

New Polar Instruments PCB repair system supports most popular CAD formats

Research of Product Frame Model Based on Reverse Engineering

To make product frame model with good size parameters and assembly accuracy, 3D measurements for current product model are established by using three-dimensional laser instrument based on reverse technology. The actual measured data are handled by using CATIA software to obtain the profile size of product’s cross, vertical section, which is then translates into CAD format. Then the similarity ratio of the product frame model is determined based on similarity theory. Product model parts are produced and assembled by using laser processing technology. Practice shows that the product framework model has good size accuracy and assembly performance, which can improve facture efficiency.

Mathematical modeling for the design of a generic custom-engineered form mill

This paper presents a mathematical model for the geometric design of a custom-engineered form milling (CEFM) cutter and develops an accurate 3D surface-based generic definition of the form mill. The proposed geometric definition of the CEFM cutter is developed in terms of biparametric surface patches using newly defined 3D rotational angles rather than the conventional 2D angles. The non-uniform rational B-spline curve fairing and sweep surface approaches are used to design the cutting edge and flank surface, respectively, of the cutter. To validate the methodology, an interface is developed that converts the proposed 3D parametric definition of the cutter into an intermediate neutral CAD format and then renders the cutter model in any CAD modeling environment. The accuracy of the mathematical model is verified by evaluating the deviation plot between the surfaces of the proposed cutter model and the surfaces developed using digitized data of an existing actual CEFM cutter. The satisfactory comparison verifies the shape design methodology for custom cutters presented in this paper. The method described here offers a simple and intuitive way of generating shape design of custom cutters for possible use in machining process simulations, finite element analysis, and other applications.

Automated 3D Reconstruction of Interiors from Point Clouds

We present a new technique for the fully automated 3D modelling of indoor environments from a point cloud. The point cloud is acquired with several scans and is afterwards processed in order to segment planar structures, which have a noticeable architectural meaning (floor, ceiling and walls) in the interior. The basic approach to data segmentation is plane sweeping based on a hypothesis-and-test strategy. From the segmentation results, the ground plan is created through cell decomposition by trimming the two-dimensional ground space using half-space primitives. An extension in height of the ground contours makes the generation of the 3D model possible. The so-reconstructed indoor model is saved in CAD format for analysis and further applications or, simply, as a record of the interior geometry.

Smoothing and simplification algorithm for Computer Aided Manufacturing paths with complex curves

Abstract Using a Computer Aided Manufacturing (CAM) system based on the studied algorithm, displacements can be achieved across complex paths at constant velocity and with high precision without intermediate stops. This allows the use of laser as a tool for marking or machining. In addition, the algorithm reduces the number of needed points for path programming. The most frequent complex curves in CAD formats are simplified to straight lines and circular arcs. To have full constant velocity auxiliary paths of acceleration and deceleration are used.

Data Transfer from Heterogeneous CAD to Division Mockup Virtual Prototype

Virtual prototype technology could integrate different CAD formats parts into an digital model. In this way the design process will be more efficient. This issue reviewed three methods to transfer data from CAD parts to virtual reality element. And find an efficient way to transfer different CAD model data to virtual prototype software Division MockUp.