A Dual Environment for 3D Modeling With User-Defined Freeform Features

Author(s):  
Thomas R. Langerak ◽  
Joris S. M. Vergeest

Modeling with freeform features has become the standard in computer-aided design. Features offer a high-level approach to modeling shapes. However, in most commercial modeling packages, only a static set of freeform features is available. A new method for user-driven feature definition is presented, as well as a method to instantiate these user-defined features on a target surface. We propose the concept of a dual environment, in which the definition of a feature is maintained parallel to its instance on a target surface. This dual environment enables dynamic feature modeling, in which the user is able to change the definition of instantiated features on-the-fly.

Author(s):  
Thomas R. Langerak ◽  
Joris S. M. Vergeest

Modeling with free form features has become the standard in Computer-Aided Design (CAD). With the increasing complexity of free form CAD models, features offer a high-level approach to modeling shapes. However, in most commercial modeling packages, only a static set of free form features is available. Researchers have tried to solve this problem by coming up with methods for user-driven free form feature definition, but failed to connect their methods to a means to instantiate these user-driven free form features on a target surface. Reversely, researchers have proposed tools for modeling with free form features, but these methods are time-intensive in that they are as of yet unsuitable for pre-defined features. This paper presents a new method for user-driven feature definition, as well as a method to instantiate these user-defined features on a target surface. We propose the concept of a dual environment, in which the definition of a feature is maintained simultaneously with its instance on a target surface, allowing the user to modify the definition of an already instantiated feature. This dual environment enables dynamic feature modeling, in which the user is able to change the definition of instantiated features on-the-fly. Furthermore, the proposed instantiation method is independent from the type of shape representation of the target surface and thereby increases the applicability of the method. The paper includes an extensive application example and discusses the results and shortcomings of the proposed methods.


Author(s):  
Vassilios E. Theodoracatos ◽  
Xiaogang Guan

Abstract This paper presents a new Computer-Aided Design (CAD) synthesis model which uses Plex Grammar as structural relationship descriptors and NURBS surface representation for constructing standard and non-standard solid entities. Here, the designer uses a syntactic design methodology for early topological and geometrical definition of the structure of concept alternatives resulting from the design process. This syntactic scheme provides the capability of describing a large set of complex structures by using a small set of simple entities. The recursive nature of the grammar and the hierarchical representation of the structure makes the description of complex structures simple and under the direct control of the designer. An object structure constructive tree is generated and subsequently translated into Plex Grammar production rules in order to form an Interconnection Matrix (ICM) expressing. The resulting Plex structure defined in the ICM expresses the topological information among entities which form the specific types of objects. By modifying the Plex grammar rules, various objects with different geometry and topology can easily be reconstructed. Compared to conventional solid modeling techniques, this approach provides more systematic object generation, easy manipulation and modification, control over congruity and the ability to represent sculptured shapes. Several examples of syntactic solid modeling applied in design synthesis will be presented for further usage in downstream applications.


2014 ◽  
Vol 597 ◽  
pp. 417-420
Author(s):  
Jeremy Zheng Li

The tooling and fixture play important roles in manufacturing and production. It affects both product quality and quantity. Better tooling and fixture can also promote cost-effective manufacturing process. This paper introduces a new type of universal clamping mechanism based on computer-aided 3D modeling, engineering structural analysis, and prototype testing. It can be applied to easily and reliably clamp different geometrical shape of work pieces per user requirements. This new clamping mechanism, with less moving components, can assist manufacturing industry for high speed production, easy part handling, precise clamping, and lower tooling cost. Keywords: Computer-aided design, automated production, 3D modeling, cost-effective, high speed manufacturing, engineering analysis, optimization, efficient;


Author(s):  
Martin K Yates

Twin pinion gear pumps are used widely in industrial hydraulics and as fuel-delivery pumps for aero engines. The kinematics of the pumping action leads to high-flow rates into and out of the meshing gears, and at the high speeds used with aerospace fuel pumps cavitation can occur. One-dimensional ‘lumped parameter’ models are often used to analyse this type of pump. These methods rely on an accurate description of the volume trapped by the meshing teeth and the flow areas during the meshing cycle. Typically, multiple computer-aided design models have to be created to calculate these values during the meshing cycle. This paper presents a mathematical method for calculating these parameters based on a parametric definition of the gear and inlet and outlet porting. Green's theorem is used to allow line integrals around the periphery of the tooth spaces to be used to calculate the volumes and flow areas. Winding numbers are used to calculate the inflow and outflow areas that are formed by the intersection of the trapped volume and the side area porting. The method is validated against computer-aided design model data. This method is well suited for incorporation in an optimisation algorithm since the geometry is defined parametrically.


Author(s):  
Konstantinas Stanislovas Danaitis ◽  
Ana Usovaitė

3D design technology is the basis for the modern computer graphics. AutoCAD 2015 is a powerful version of computer-aided design system. We can solve complex tasks, without which this instrument can’t be solved in general. Using 3D design technology we not only save time working with a drawing. The geometric models are the foundation of the design basics, for working with drawing we can create projections, footnotes, sections and other modern graphics elements. AutoCAD can use and process the data from the model. This progressive design technology includes all parts of the design, starting from machine details, furniture and finishing with architectural forms of complex object models.


1995 ◽  
Vol 117 (1) ◽  
pp. 2-9 ◽  
Author(s):  
R. Gadh ◽  
F. B. Prinz

The current paper discusses a fundamentally new approach to defining and finding interactions in computer-aided design (CAD) forms or features. Feature classes are defined using a high-level abstract entity called a loop. Loops define features in a general manner and aid in the definition of feature boundaries as well. Interactions between features exist due to interactions between their boundaries. Several types of interactions are defined and automatically determined from the boundary representation solid model of the part subsequent to performing feature extraction.


Author(s):  
Juan A. Rami´rez ◽  
Rafael E. Va´squez ◽  
Luis B. Gutie´rrez ◽  
Diego A. Flo´rez

This paper presents the mechanical/naval design process of an underwater remotely operated vehicle (ROV), required to obtain reliable visual information, used for surveillance and maintenance of ship shells and underwater structures of Colombian port facilities. The design was divided into four main subsystems: mechanical/naval, hardware, software and guidance, navigation and control. The most relevant design constraints were evaluated considering environmental conditions, dimensional restrictions, hydrostatics, hydrodynamics, degrees of freedom and the availability of instrumentation and control hardware. The mechanical/naval design was performed through an iterative process by using computational tools, including Computer Aided Design CAD, Computer Aided Engineering CAE, Computational Fluid Dynamics CFD and a high level programming environment. The obtained design ensures that the reliable operation of the robot will be achieved by using a consistent construction process. The new ROV constitutes an innovative product in Colombia, and it will be used for surveillance and oceanographic research tasks.


Author(s):  
Владимир Аверченков ◽  
Vladimir Averchenkov ◽  
Андрей Васильев ◽  
Andrey Vasilev ◽  
М. Хейфец ◽  
...  

The problems of a technological heredity impact upon quality formation and machinery operation properties are considered. The significance of the definition of quantitative dependences taking into account technological heredity manifestation is shown. Simulators for the computer-aided design of engineering ensuring parts quality required are offered.


Author(s):  
Robert Lipman

The STEP File Analyzer is a software tool that generates a spreadsheet or a set of CSV (comma-separated value) files from a STEP (ISO 10303 –STandard for Exchange of Product model data) Part 21 file. STEP files are used to represent product and manufacturing information (PMI) and for data exchange and interoperability between Computer-Aided Design (CAD), Manufacturing (CAM), Analysis (CAE), and Inspection (CMM) software related to the smart manufacturing digital thread. STEP is also used for the long-term archiving and retrieval of product data. A spreadsheet simplifies inspecting information from the STEP file at an entity and attribute level. Typical STEP file viewers show a 3D visualization of the part or model represented by the STEP file. The viewers usually have a high-level hierarchical display of the information in the STEP file where the user can drill down to individual attributes of parts. However, there is no way to view all of the actual STEP entities and their attributes at once. The STEP File Analyzer provides this capability by creating a spreadsheet from the STEP file. The STEP File Analyzer also generates reports for PMI Representation, PMI Presentation, and Validation Properties based on Recommended Practices defined by the CAx Implementor Forum (CAx-IF) [5]. The objective of the CAx-IF is to advance CAx (mainly Computer-Aided Design and Engineering) software system STEP translator development and to ensure that user requirements for interoperability are satisfied.


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