Feature-based Design System Research Articles

Low-carbon building design and practice in severe cold areas

With a vast territory and seven climate zones, China’s urbanization is constantly improving while building energy conservation and emission reduction are facing severe challenges, especially in severe cold areas. In China’s Liaoning Province, urban public buildings and rural residential buildings consume huge amounts of energy. According to the characteristics of Liaoning, “passive technology advanced, active technology second” is the best choice for energy saving and emission reduction. Taking Sino-German Energy Conservation Demonstration Center in Shenyang Jianzhu University as an example in this paper, through analysis of the operation monitoring data of energy consumption, the objective is to provide a good reference method and a design strategy for the near zero energy buildings in the severe cold areas and to verify its feasibility. At the same time, the parametric design technique is applied to feature-based design system, such as multi objective optimization and genetic algorithm combined simulation technology, Rhino Grasshopper Energy plus energy saving technology and cost-benefit analysis model to obtain the optimal solution. It provides innovative technology demonstration for building energy conservation in the severe cold areas.

A geometric feature-based design system of full parametric association modeling of standard cam for automotive stamping dies

Cam mechanism is the most difficult part in the design and manufacture of stamping dies of automobile panels. The same series of cam products need to meet the needs of different working angles. Each specification needs to design and prepare a three-dimensional model, which brings great challenges to the design, editing, and management of the models. Therefore, a new design system of full parametric association modeling based on geometric features for standard cam was proposed, which is seamlessly integrated in NX software platform. The models of different work angles of the same series of cam are integrated into a fully parametric model. The specification and assembly location of standard parts, activation and suppression of detail features will automatically change with work angle based on parametric feature and association constraint technique. By modifying the work angle, the system can automatically instantiate different specification models of cam. Furthermore, the optimized design of cam structural is easier to achieve by motion simulation and finite element analysis based on the parametric model and geometric features. The system can also output the BOM table, when the model is instantiated. The cam of KMACG 600 demonstrates that the newly developed system shows an excellent performance on the model simplification, data management, and optimization design of cam, which can generate high quality design and reduce cost and designing time significantly.

Feature-based non-manifold modeling system to integrate design and analysis of injection molding products

Current CAE systems used for both the simulation of the injection molding process and the structural analysis of plastic parts accept solid models as geometric input. However, abstract models composed of sheets and wireframes are still used by CAE systems to carry out more analyses more efficiently. Therefore, to obtain an adequate abstract model, designers often have to simplify and idealize a detailed model of a part to a specific level of detail and/or abstraction. For such a process, we developed a feature-based design system based on a non-manifold modeling kernel supporting feature-based multi-resolution and multi-abstraction modeling capabilities. In this system, the geometric models for the CAD and CAE systems are merged into a single master model in a non-manifold topological representation, and then, for a given level of detail and abstraction, a simplified solid or non-manifold model is extracted immediately for an analysis. For a design change, the design and analysis models are modified simultaneously. As a result, this feature-based design system is able to provide a more integrated environment for the design and analysis of plastic injection molding parts.

Feature-based design for process planning of the forging process

The forging process has traditionally been done by skilled experts using their past experience, intuition and the trial and error method. Even in this computer era, only a very few computer aided tools are available for this oldest manufacturing process. The present work explains the development of a feature based design system that has been applied in the concept-to-manufacturing stages of the forging process. It is broadly divided into four modules namely, feature-based design (FBD), virtual factory environment (VFE), feature mapping for forging (FMF) and process planning (PP). The FBD module is used for the design, modelling, synthesis, representation and validation of the component for the forging application. It uses integrated features, which are pre-defined as feature templates in the developed feature library. While instancing these integrated features, the database gets/derives the information required for the design, modelling, process planning and manufacturing stages of the component as its attributes, from the user/knowledge base. After creating the component, the integrated features present in the model are validated with respect to the forging process. The VFE module defines the layout model of the factory on the computer, and provides the database for the machines, machine tools, tools, work pieces, etc. The FMF module contains the knowledge base for preparing the forge model, die impressions, parting line/surface, etc. The PP stage is used to find the process parameters like forming sequence, shape of pre-form and finisher die sets, temperature of billet and dies, forming speed, die stroke, material for die sets and workpieces, etc. This feature based design system has been built using existing CAD, programming and spread sheet software tools namely CATIA®, MS-Visual Basic® and MS-Excel®, which not only save developmental effort, but also make full use of the functionalities of these commercial software tools. This paper explains the developed system with a case study.

Feature-based design for process planning of machining processes with optimization using genetic algorithms

The development of a feature-based design environment that can be applied in the concept-to-manufacturing stages of the machining process is explained. It is broadly divided into four modules, namely, feature-based design (FBD) environment, virtual factory environment (VFE), operation-based feature mapping (OBFM) and optimization using genetic algorithms (GA). The feature-based design environment module is used for the design, modelling, synthesis, representation and validation of the components for machining application. It uses integrated features, which are predefined as feature templates in the feature library. While instancing these integrated features, they get/derive the information required for the design, modelling, process planning and manufacturing stages of the components as their attributes, from the user/knowledge base. After creating the component, integrated features present in it are validated with respect to its application, namely machining process. The VFE module defines the mathematical model of the factory in the computer, which provides the database for operations, machines, cutting tools, work pieces, etc. The knowledge base maps validated features of the component into operation sets in the first phase of the OBFM stage. Each operation in the operation sets can be carried out using different machines and cutting tools in the factory. All these possible choices are obtained in the second phase of OBFM. GA is used to find the optimal sequence of operations, machines and cutting tools for different criteria. Provisions are also available to generate NC codes for operations, which are to be carried out with NC or CNC machines, if selected. Thus, the optimal process plan for the selected criteria with respect to the given factory environment is found for the modelled component. The feature-based design system developed is built on existing CAD, programming and spread-sheet software tools, namely CATIA®, MS-Visual Basic® and MS-Excel®, which not only save developmental effort, but also make full use of the functionalities of these commercial softwares. This paper explains the developed system with a case study.

A Web-based service for distributed process planning optimization

The advance and pervasive applications of the Web-enabled computations are exerting a profound influence on product design and manufacturing processes, and one of the major technical shifts for product development systems is toward supporting distributed collaboration. A key component for this trend is to develop a service model that enables product development systems to be triggered and manipulated from a remote computer, so as to provide a more flexible manner to share and interoperate the executive codes and processing data. In this paper, a process planning optimization module has been wrapped as a Web-enabled service and deployed in the Internet to support distributed design and manufacturing analysis. The module consists of several optimization approaches, and a Tabu search-based approach, which can optimize the selection of machining resources, determination of set-up plans and sequencing of machining operations to achieve optimal process plans, is elaborated to illustrate the process. The Web-based service has been integrated with a distributed feature-based design system, and the latter can generate design models and re-represent them in an XML representation based on VRML and attributes of features to provide the input of the former. Through effective utilization of the Web and Java technologies, the established service and relevant system can be used by a distributed design team to organize concurrent engineering activities effectively.

A Web-based process planning optimization system for distributed design

In this paper, a process planning module, which can optimize the selection of machining resources, determination of set-up plans and sequencing of machining operations to achieve optimized process plans, has been wrapped as services and deployed in the Internet to support distributed design and manufacturing analysis. The module includes four intelligent approaches, and a Tabu search-based approach is explained in this paper to illustrate the optimization process. A Web-based prototype system has been setup for users to carry out visualization-based manipulations and process planning of design models by invoking the services remotely. The Web-based system has been integrated with a distributed feature-based design system, and the latter can generate design models and re-represent them in an XML representation based on VRML and attributes of features to provide the input of the former. Through effective utilization of the Web and Java technologies, this system is independent of the operating system, scalable and service-oriented, and can be used by a geographically distributed design team to organize concurrent engineering design activities effectively.

An efficient algorithm for automatic machining sequence planning in milling operations

Machining sequence planning can be considered as one of the most important functions of manufacturing process planning. However, less attention has been paid to automation of this function in contemporary computer-aided process planning systems. This paper describes an efficient algorithm for automatic machining sequence planning in 2.5D milling operations. It is programmed in LISP and forms the machining sequence planning module of a CIM system. This module is integrated with a feature-based design system that determines required machining operations and parameters for each machining operation. This information is then sent to the machining sequence planning module for determining proper machining sequence plans for producing the part. The algorithm generates feasible machining sequences based on the bilateral precedence between machining operations. The algorithm results in minimized tool changes.

Manufacturing features: Verification interaction accessibility and machinability

A major problem in CAD/CAM integration lies in the difficulty in representing the component definition adequately for all applications. Features are considered as a main factor in the CAD and CAM link because various design, engineering and manufacturing data can be associated with a feature. However, tagging feature labels onto geometry does not guarantee the geometric correctness of the resultant feature; knowledge of the topology and analysis of the geometry is needed to correctly identify the validity of the resultant feature. This paper discusses a feature-based design system capable of representing 2.5D components in terms of manufacturing features such as holes, slots and pockets, which are associated with distinctive manufacturing processes. The system is capable of verifying all the defined features by comparing the definition of the resultant features against those of the applied features. Feature interactions are considered to investigate the effect of the interaction on the validity, accessibility and machinability of each feature. Individual features can be extracted from the product model, where all the information about the product is held, for analyses. Each volumetric feature corresponds to a solid that can be removed by one or more machining operations; as a consequence of applying volumetric features, surface features are generated. These surface features provide enough information to enable the validity and machinability of the individual features to be determined and to establish the possible routes in which the feature can be accessed, if any. The proposed approach has been explored in a rapid prototyping test bed consisting of product modelling environment coupled with a solid modeller.

Feature-based representation for manufacturing planning

Improved integration using product models in a computer aided design and manufacture environment implies that there is an enhanced need to provide information support across a wide range of applications. In a typical situation concerned with mechanical products, these applications are likely to include detail design, process planning and assembly planning. Features have frequently been used to support these and other applications individually, but single feature representations that simultaneously meet the information needs of a number of applications are unusual. Assembly and process planning are two important aspects of an integrated design and manufacture system, and a formal structure for their representation in a feature-based design system is presented. Features are considered to be machined volumes and are described in a hierarchical taxonomy that is designed to be useful across a range of machined components. The assembly structure is also defined hierarchically with the (machining) features forming the basic entities in the assembly. Assembly relationships among features are defined in the form of mating relationships that are carried by the features. A set of mating relationships between pairs of features has been defined after having studied the literature and a number of engineering products. An integrated data structure containing process planning information from earlier research work and the assembly mating relationships is presented and forms the basis of class definitions for each level in the assembly hierarchy. Object-oriented programming techniques have been used to implement a prototype system using the ACIS solid modelling kernel. The research has illustrated the feasibility of using a single feature representation to support a number of activities within a computer integrated manufacturing environment.

Manufacturing responsiveness through integrated process planning and scheduling

This paper describes a novel approach to improve manufacturing responsiveness, defined as the ability of a manufacturing system to make a rapid and balanced response to the predictable and unpredictable changes characterizing today's manufacturing environments. The approach aims at creating a dynamic environment that is capable of reacting to factory conditions and which has a significant impact on the reduction of cost, lead time and inventory. The concurrent engineering concept of information sharing to support all the product development phases is employed here. Techniques such as design for manufacture have been applied to the design-process planning interface. Efforts have been made towards eliminating the divisions between process and scheduling activities using the concept of resource elements, which are the exclusive and shared capability boundaries between processing elements in the manufacturing facility. A prototype integration system has been implemented consisting of a knowledge base with facility modelling functions, an intelligent feature-based design system, a featurebased process planning system and a simulation-based scheduling module.

A single representation to support assembly and process planning in feature-based design machined parts

The need for a product model that can support the modelling requirements of a broad range of applications leads to the application of a feature-based model within a computer aided design environment. An important requirement in feature-based design for manufacture is that a single feature representation should be capable of concurrently supporting a number of different applications. Assembly and process planning are seen as two crucial manufacturing applications and a formal structure for their representation in a feature-based design system is presented. This research addresses two basic questions relating to the lack of a unified definition for features and the establishment of a feature-based representation for assembly. Thus the concept of designing with features is extended by incorporating assembly and process planning information with the geometrical and topological details of component parts. A prototype system has been implemented using an object-oriented programming technique which provides a convenient method for adding functionality to the geometric reasoning process of features and the complex relationships between the parts that make up the assembly. The feature-based model is embedded in the ACIS object-oriented solid modeller kernel.

Feature-based design by volumetric machining features

Substantial research efforts have been spent on feature applications towards the integration of CAD and downstream manufacturing functions such as process planning. However, the majority of contemporary feature-based systems cannot handle the interactions of features in practical applications. Feature interactions cause problems in feature recognition as well as feature-based design systems. This paper presents an approach to represent and analyse features in a featurebased design system. In this system, a part is modelled by volumetric machining features, which are then decomposed into air volumes and material volumes. Geometric reasoning is used to evaluate and analyse the features incrementally during the design stage. Feature interactions are detected by the possible interactions among material volumes. Several interacted or face-contacted material volumes can be clustered into a single-material volume. For each material volume, a tool-swept volume is generated to represent the space to be removed in the machining process. The complete feature instancing process is governed by the validation rules to ensure that the part is manufacturable.

Automated feature validation for creating/editing feature-based component data models

In a feature-based design system, it is necessary to check if a feature is valid (i.e. dimensions and class are proper) before adding it to the component model, and to detect if there will be any changes in the existing features which interact with it. The same applies to an existing feature to be modified and its interacting features when editing a feature model. This ensures a precise feature model of component design for the downstream applications. It is a commendable goal to automate the process of feature validation, which in turn increases the system's capability and intelligence, thus reducing the requirement on the designer's effort. This paper presents a Boolean operation-based systematic methodology of automating feature validation by checking feature dimensions and class, respectively. It briefly introduces a feature-based component data model (FBCDM) suitable for process planning and NC programming, and then discusses in detail the problem of feature validation and the algorithms of feature validation for creating/editing FBCDMs.

Modeler-independent feature recognition in a distributed environment

Solid modelers and other CAD/CAM subsystems are moving to distributed heterogeneous computing environments, so as to support design and manufacturing processes that are temporally and spatially distributed. Communication and collaboration among the software components of such distributed systems require protocols for accessing remote objects. This paper discusses an approach that provides transparent access to diverse solid modelers in a distributed environment. A solid modeler is augmented with a software wrapper, called an adaptor, so as to provide a uniform application programming interface (API). Applications interact with the uniform API and need not concern themselves with the specifics of the modeling systems used. API calls are implemented in a client-server architecture, in which a modeler and its adaptor function as a geometry server, and various applications communicate with the server through remote procedure calls (RPCs). A few adaptors have been implemented at the University of Southern California's Programmable Automation Laboratory, and have been used routinely for several years. This paper discusses adaptor design problems and our approach to their solutions. It illustrates the application of our methods through an example that involves the incremental recognition of machinable features in a distributed environment. This environment includes a geometry server, a simple feature-based design system, a state-of-the-art feature recognizer, and a graphics renderer, all running as separate processes in different machines. To our knowledge, this is the first documented effort in which a complex application such as feature recognition is capable of running, unmodified, on top of modelers based on constructive solid geometry or on boundary representations, which are fundamentally different.

Automated setup selection in feature-based process planning

Setup planning is a critical part of automated process planning. Setup is determined by several factors, tool approach direction and tolerance specification are two major ones. Most of the current process planning systems consider only the tool approach direction. This results sometimes in incorrect parts. To convert the tolerance requirements from design into a process plan, tolerance analysis must be applied. Correct datums must be selected for an optimum setup plan that will assure the required tolerances. This paper describes an approach that uses the tolerance specification in a feature based design system to generate setup plans with explicit datum elements. These setup plans are ranked by the number of setups required and the estimated accuracy of the resultant dimensions. The ranked setup plans are then reported to the fixture planner for fixture selection. The focus on this research is an automated tolerance analysis approach for selecting setups and datums for prismatic workpieces in the design system.

A new feature-based design system with dynamic editing

This paper proposes a feature-based design system for prismatic parts in which predefined 3D features, instead of low-level 2D lines and points, are used as entities for representation and manipulation. Two special sets of functions, a new construction function and a dynamic editing function, enable designers to freely construct and modify parts. The parts are saved as feature-based files in CSG form, while a B-rep form is also created. The feature-based file allows the proposed 3D part-design system to be easily integrated into CAPP/CAM systems without complex feature-recognition and -extraction processes. Object-oriented concepts are used in implementing the proposed system, and examples are given to show its feasibility and effectiveness.

A representation formalism for feature-based design

Feature-based design is regarded as a promising approach for design. However, it lacks a formal methodology for system development and operation. One repercussion of this is that feature-based design is, at present, implemented in a relatively ad hoc manner. This paper aims to address this deficiency by establishing a domain-independent representation formalism for feature-based design. The proposed representation formalism consists of a feature algebra, a design algorithm and a system architecture/development methodology. The proposed representation formalism aims to make it possible to develop a feature-based design system for a specific design domain in a structured way. In addition, by using the representation formalism as a research framework, other issues of feature-based design can be addressed. The research in this paper contributes to several aspects of design research, especially to the area of integrating concurrent engineering and feature-based design.

Feature-based design of electronics assemblies

Feature-based design is an approach that promises substantial benefits in capturing and transferring a designer's intent to other stages of design and manufacturing, thereby helping to integrate the diverse functions associated with design and manufacturing. While feature-based design has considerable potential, it has been applied almost entirely to mechanical design. Furthermore feature-based design has been implemented in a relatively ad hoc manner and, consequently, much of the work on feature-based design cannot be readily applied to other domains. This paper aims to address some of this deficiency by describing a feature-based design system for electronic manufacture that is based on the firm formalism of a feature algebra and a feature-based design algorithm. An electronics assembly feature taxonomy is developed, together with feature operators and validation scheme. These are used to build a prototype feature-based design system called Feature-Based Design of Electronics Assemblies (FEBEA). The fo...

Feature-based Design and the Object-oriented Approach

SUMMARY Object-oriented programming is claimed to be the software technology for the 1990s and beyond. Yet the evolution of computer-aided design (CAD) for mechanical design has led to feature-based design being widely championed as the preferred solid modelling approach. This paper reports an investigation into the practicalities of amalgamating both approaches to produce an object-oriented feature-based design system to exploit the benefits of each. An object-oriented CAD system was successfully implemented using AutoLisp and the object-oriented framework was found to match well to the requirements of both features and CAD modelling. It was also found that it was quite possible to provide a user interface that isolates the main CAD functionality from the user. Objects were also found to be usable with CAD when operating within a more integrated environment.