A Collaborative Framework for Integrated Part and Assembly Modeling

Assemblability analysis and evaluation play a key role in assembly design, assembly operation analysis and assembly planning. This paper proposes an integrated approach to assemblability analysis and evaluation for STEP (STandard for the Exchange of Product model data, officially ISO 10303) based electro-mechanical products. In the paper, two assembly representation models are first brought up and elaborated: the EXPRESS/XML schema based model and the NIST object-oriented UML-based Open Assembly Model (OAM). These two models are then integrated together; the OAM incorporates the EXPRESS/XML schema based assembly model to completely capture the detailed geometric information. Based on STEP, the proposed assembly evaluation approach uses the EXPRESS/XML schema based model as the information source, and the evaluation structure covers not only the assembly parts’ geometric and physical characteristics but also takes into account the assembly operation data necessary to assemble the parts. The feature of this approach is the linkage of the STEP product definition to the fuzzy analytic hierarchy process (AHP) for assembly evaluation. The proposed approach has the flexibility to be used in various assembly methods and different environments. The case study shows that the proposed approach is feasible.

Assembly model of mechanical products for their life cycle simulation

During the recent years, a great change in engineering was replacing the conventional CAD/CAM/CAE systems with highly integrated product lifecycle management (PLM) systems. Earlier concentrations on specific fields of engineering replaced by a product concentration where an integrated product model has capability to accommodate all information needed during the lifecycle of the product from the first sketch to the successful recycling. Several new problems were emerged during implementation of PLM purposed product models in the industrial practice. Recently, very complex models include high number of entities for parts, assemblies, simulation results, manufacturing processes, equipment control programs, etc. It is increasingly difficult to track consequences of an entity change on other entities. The second new problem is about the increasing medium role of product model. Product models are demanded to carry intent of engineers for the application at development of those models by other engineers. However, recent product models are not in the possession of the representation capabilities necessary. In this paper, the authors concentrate on this second problem. They made an attempt to define an extension to the currently prevailing product models in order to enhance their capabilities for the support of human intent based decision making during development, manufacturing, and application of products. In the organization of this paper, influencing of human intents is considered in engineering modeling processes and extending product model to information content is conceptualized and discussed. In the rest of the paper, new approach, concept, and method are introduced for communication and modeling of information content.

DFM method can only be realized with the help of complete, unified modeling of product requirements, functionalities, assembly relations, shape, dimensions and tolerance, and manufacturing requirements. Beyond the capabilities of current CAD systems on modeling of geometric aspects of product, a fully-associated model defined by unified modeling language is proposed to facilitate the DFM. Function model is created to define the product functional structure and interaction between functional objects. Function model is transformed and associated with the assembly model by function feature. Product structure is defined by assembly model and assembly connection features. Product simplification can be achieved by function optimization and assembly simplification method. The functions and assembly connection are further break down to a feature-based model. Form feature is mapped into manufacturing features and be verified to the consistence with the capabilities of enterprise's manufacturing resources and production type. The unified model associates information from customer needs, product function, components behaviors, part geometry and manufacturing resource capabilities. It can help to fully understand of various impacts coming from each stage of product lifecycle, especially the impacts of manufacturing processes.

Researchers and practitioners have attempted to solve problem of robot control by using of well-proved product models. Existing product modeling methods offer quasi integration because appropriate integrated robot process model is not available. The authors propose a modeling of the robot system that has the capability of integrated description of product, robot and robot process. Advanced concepts as feature and associativity definitions together with task oriented robot process gained an extended application in the proposed model. This paper presents the new modeling for integrated application of part, assembly and robot process models at robot assembly of mechanical products. The main purpose of this integration is product model driven definition of robot assembly trajectories. The main contribution is an attempt to define shapes and part positions for robot assembly by using of form features instead of geometric elements. Form feature model objects carry intent of engineers for technical content of modeled environment. The paper introduces actual issues of robot assembly and outlines the concept of the authors for product model driven modeling of robot assembly. Information for assembly in feature based product model and robot process model features are explained. Following this, an extended feature concept for modeling of robot system is discussed. Finally, integrated model of robot assembly system and role of form features in it are concluded.

Reconfigurable flexible assembly model and implementation for cross-category products

Angle grinder use in grinding a product and for high performances application, like deburring in foundries and construction. Consequently, this study investigates about the sustainability design of angle grinder with integration of Design for Manufacturing and Assembly (DFMA) analysis. Design for Manufacturing and Assembly (DFMA) is a process that produce a good product which is minimize complexity and number of part that lead to time and cost reduction in development. Sustainability design means a design solution that are advantageous to both human and nature in a complete and combined way. Sustainability design in this research include the production and assembly part which is analysis using DFMA method. The design solutions are minimizing the part number and assembly time problem regardless the costs, materials issues and selection of manufacturing process. Using the DFE method combined with Boothroyd and Geoffrey DFMA principle, the analysis on angle grinder by using the 3D scanning method in drawing some part using the Catia software and the sustainability analysis using Solidwork software is done. The result for current product efficiency is 21.3% with 15.34 KgCO2, 2.10×10−2 KgPO4, 15.5 KgSO2, 1.95 MJ produce in producing one angle grinder. Through this study, expecting 25% of reduction in all criteria study.

CAD Software such as CREO and SolidWorks are used to develop mechanical parts and assemblies and do not explicitly support the function of the feature, component, part or assembly. Therefore, the reasoning of why and how a design is developed has not been incorporated into current CAD systems. At the same time, CAD systems support sophisticated functions such automated routing, modelling and simulation of dynamic and geometric properties and design solutions tracking. In this paper we investigate (a) to what degree CAD tools have advanced beyond drafting tools to include cognitive supports that facilitate problem solving and (b) which possibilities exist to enhance CAD with cognitive tools that with focus on the intersection between cognitive psychology, interaction design and design engineering remain unexplored.

Much work has been carried out on the creation of protocols for the exchange of data between CAD systems, but very little on the transfer of knowledge. The knowledge behind the development of a product is vital if modifications and adaptations are to be made within a concurrent development environment. Current CAD systems only contain a limited level of product knowledge through user-defined parametric structures. It is the underlying relationships in these programs that need to be communicated between systems, rather than the form of their individual programming languages. A generic structure is proposed that is able to handle both the current level of parametric programming and is suited to the resolution of conflict through the use of constraint modelling procedures. The structure of a parametric description is described and decomposed into its fundamental components. These components are then re-formed within a truth maintenance structure to allow a transfer protocol to be created. The derived protocol structure is then demonstrated on a number of simple examples.

Current CAD systems have inherent bottlenecks, which diminish possible achievements for architectural practices. Among these shortcomings there are two the paper will deal with. Firstly, traditional CAD relies on a pure geometric model. All non-geometric information about objects of architectural interest has to be attached to these geometric entities. This restricts the ability to describe semantically dependent relationships. Secondly, the integration of different design tools for building and construction is still at its very beginning. The data exchange remains restricted, since it is based on a fairly low semantic level of a document-based exchange of information, such as geometric representation in DXF or IGES, rather than on a high semantic level of a model-based exchange.

Midsurface abstraction from 3D solid models: general theory and applications

Computer simulation packages have had success in predicting filling behavior in extremely complicated geometries. However, most of the current numerical implementation is based on a hybrid finite‐element/finite‐difference solution with the middle‐plane model. This kind of model leads to some inconvenience in applications. Instead of using the middle‐plane as the datum plane, the surfaces of the cavity are used as datum planes in this article. Additional boundary conditions in the gapwise direction are employed to keep the flows in the surfaces at the same section coordinative. Comparisons with experimental results obtained with an instrumented test mold and C‐Mold results show good agreement in terms of pressure traces and melt‐front advancement. It is demonstrated that the present formulation is well suited to handle cavities generated directly by current CAD systems. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 125–131, 2001

Solid model abstraction is an integral part of parallel and process design. It is required for simulation and optimisation of the design and consists of retrieving a simplified model from the solid one, with appropriate dimension reduction and details removal. Unfortunately, current CAD systems do not provide the means for easy simplification of forms. Ongoing research efforts on abstraction yield some possible approaches. These attempt to generate the abstract model using expert systems, medial axis transforms or medial surfaces. A feature-based approach is presented. Analysts usually think about objects in terms of sets of forms rather than in terms of geometrical and topological entities. So, given an object and its description in terms of form features, the approach constructs a simplified model of this object using morphological information of the form features. The abstraction process has two parts: simplification and idealization. The simplification part removes any non-pertinent features from the initial model, while the idealization part idealizes the resulting objects according to the goal of the analysis.

To transform CAD model into virtual assembly model, model transformation was divided into two processes, namely part model transformation and assembly constraint model transformation. With secondary development of SolidWorks system, both part model and assembly constraint model were extracted form SolidWorks model. The OpenFlight database, which is a standard format for virtual reality simulation, was used to represent the hierarchical model of part. Assembly constraint model was expressed by object-oriented hierarchical model in text file. These two models were associated with each other using unique name or number. By loading part files and assembly constraint file, the assembly model was reconstructed in virtual assembly system. The experiment verified that the presented method was effective.

Changes in engineering for development of product in the direction of increased complexity, more variants, and customer demand orientation stimulates implementation of advanced information technology in the form of virtual space. For this reason, concept of integrated product model has been implemented in comprehensive descriptions for lifecycle management of product information. Communication between engineer and modeling procedure is a critical factor. The authors identified data orientation of the recent integrated product modeling as a barrier for more efficient communication on user interfaces of product modeling systems. As a possible contribution to development of solution for this problem in industrial professional modeling systems, they propose content oriented layers between human and data oriented models in this paper. Following this, integration issues in content oriented product model are discussed. Next, relevant functions and modeling techniques for the handling of modeled object information are introduced and evaluated. Finally, a method is shown for the propagation of changes initiated for modeled objects in their affect zones.