Review of research in feature-based design

Research in feature-based design is reviewed. Feature-based design is regarded as a key factor towards CAD/CAPP integration from a process planning point of view. From a design point of view, feature-based design offers possibilities for supporting the design process better than current CAD systems do. The evolution of feature definitions is briefly discussed. Features and their role in the design process and as representatives of design-objects and design-object knowledge are discussed. The main research issues related to feature-based design are outlined. These are: feature representation, features and tolerances, feature validation, multiple viewpoints towards features, features and standardization, and features and languages. An overview of some academic feature-based design systems is provided. Future research issues in feature-based design are outlined. The conclusion is that feature-based design is still in its infancy, and that more research is needed for a better support of the design process and better integration with manufacturing, although major advances have already been made

Parametric CAD modeling: An analysis of strategies for design reusability

CAD model quality in parametric design scenarios largely determines the level of flexibility and adaptability of a 3D model (how easy it is to alter the geometry) as well as its reusability (the ability to use existing geometry in other contexts and applications). In the context of mechanical CAD systems, the nature of the feature-based parametric modeling paradigm, which is based on parent-child interdependencies between features, allows a wide selection of approaches for creating a specific model. Despite the virtually unlimited range of possible strategies for modeling a part, only a small number of them can guarantee an appropriate internal structure which results in a truly reusable CAD model. In this paper, we present an analysis of formal CAD modeling strategies and best practices for history-based parametric design: Delphi's horizontal modeling, explicit reference modeling, and resilient modeling. Aspects considered in our study include the rationale to avoid the creation of unnecessary feature interdependencies, the sequence and selection criteria for those features, and the effects of parent/child relations on model alteration. We provide a comparative evaluation of these strategies in the form of a series of experiments using three industrial CAD models with different levels of complexity. We analyze the internal structure of the models and compare their robustness and flexibility when the geometry is modified. The results reveal significant advantages of formal modeling methodologies, particularly resilient techniques, over non-structured approaches as well as the unexpected problems of the horizontal strategy in numerous modeling situations. (C)2016 Elsevier Ltd. All rights reserved.Camba, JD.; Contero, M.; Company, P. (2016). Parametric CAD modeling: An analysis of strategies for design reusability. Computer-Aided Design. 74:18-31. doi:10.1016/j.cad.2016.01.003S18317

ANNOTATION MECHANISMS TO MANAGE DESIGN KNOWLEDGE IN COMPLEX PARAMETRIC MODELS AND THEIR EFFECTS ON ALTERATION AND REUSABILITY

El proyecto de investigación propuesto se enmarca dentro del área de diseño de producto con aplicaciones de modelado sólido CAD/CAM (Computer Aided Design/Computer Aided Manufacturing). Concretamente, se pretende hacer un estudio de las herramientas de anotación asociativas disponibles en las aplicaciones comerciales de modelado CAD con el fin de analizar su uso, viabilidad, eficiencia y efectos en la modificación y reutilización de modelos digitales 3D, así como en la gestión y comunicación del conocimiento técnico vinculado al diseño. La idea principal de esta investigación doctoral es establecer un método para representar y evaluar el conocimiento implícito de los ingenieros de diseño acerca de un modelo digital, así como la integración dinámica de dicho conocimiento en el propio modelo CAD, a través de anotaciones, con el objetivo de poder almacenar y comunicar eficientemente la mayor cantidad de información útil acerca del modelo, y reducir el tiempo y esfuerzo requeridos para su alteración y/o reutilización.Dorribo Camba, J. (2014). ANNOTATION MECHANISMS TO MANAGE DESIGN KNOWLEDGE IN COMPLEX PARAMETRIC MODELS AND THEIR EFFECTS ON ALTERATION AND REUSABILITY [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/45997TESI

CAD learning in mechanical engineering at universities

In this study, we attempt to compile all the CAD-related concepts, contents and working methods that students of mechanical engineering should learn at universities. To do so, we first study the background to CAD-related methodologies. In second place, we compile the results of surveys administered over the past three years to our students of CAD studying mechanical engineering at our university. In third place, different publications in the literature relating to the need for CAD in industry are studied to understand the sort of CAD training that is needed in industry. In fourth place, an exploratory analysis is performed of the CAD-related contents taught at the 50 universities that top the QS (Quacquarelli Symonds) ranking. In fifth place, a survey of possible CAD-related contents is administered to teachers, instructors, and experts in CAD from those 50 leading universities in the QS ranking. The basic pillars of modeling in 3D are: methodologies of modeling, solid modeling, assemblies, and the design of technical drawings. The use of 3D printers in CAD learning means that thinking, designing, and manufacturing any object is easy at university. Knowledge of top-down/bottom-up/in-context methodologies has to be widened both for industry and for students. Design intent must be introduced in CAD from the very beginning so that all the models are flexible and robust. The students expressed a preference to learn the concepts through a set of good practice exercises and to be evaluated by completing a final course assignment of their choice

An exploration of the IGA method for efficient reservoir simulation

Novel numerical methods present exciting opportunities to improve the efficiency of reservoir simulators. Because potentially significant gains to computational speed and accuracy may be obtained, it is worthwhile explore alternative computational algorithms for both general and case-by-case application to the discretization of the equations of porous media flow, fluid-structure interaction, and/or production. In the present work, the fairly new concept of isogeometric analysis (IGA) is evaluated for its suitability to reservoir simulation via direct comparison with the industry standard finite difference (FD) method and 1st order standard finite element method (SFEM). To this end, two main studies are carried out to observe IGA’s performance with regards to geometrical modeling and ability to capture steep saturation fronts. The first study explores IGA’s ability to model complex reservoir geometries, observing L2 error convergence rates under a variety of refinement schemes. The numerical experimental setup includes an 'S' shaped line sink of varying curvature from which water is produced in a 2D homogenous domain. The accompanying study simplifies the domain to 1D, but adds in multiphase physics that traditionally introduce difficulties associated with modeling of a moving saturation front. Results overall demonstrate promise for the IGA method to be a particularly effective tool in handling geometrically difficult features while also managing typically challenging numerical phenomena.Petroleum and Geosystems Engineerin

A Review of Prosthetic Interface Stress Investigations

Over the last decade, numerous experimental and numerical analyses have been conducted to investigate the stress distribution between the residual limb and prosthetic socket of persons with lower limb amputation. The objectives of these analyses have been to improve our understanding of the residual limb/prosthetic socket system, to evaluate the influence of prosthetic design parameters and alignment variations on the interface stress distribution, and to evaluate prosthetic fit. The purpose of this paper is to summarize these experimental investigations and identify associated limitations. In addition, this paper presents an overview of various computer models used to investigate the residual limb interface, and discusses the differences and potential ramifications of the various modeling formulations. Finally, the potential and future applications of these experimental and numerical analyses in prosthetic design are presented

Reusability and Flexibility in Parametric Surface-based Models: A Review of Modelling Strategies

CAD systems are indispensable tools in the product design and development process. Through the creation of parametric 3D models,they increase productivity, enable the design of highly complex parts, improve collaboration between different work teams and reduce time to launch. Nevertheless, during the design process there are many different modelling solutions to generate any one part, and the robustness and flexibility of a model depends to a great extent on the experience of the designer. This dependence on individuals rather than methodologies has a negative impact on downstream engineering activities,as many models are not easily editable. Developing a methodology to produce flexibleand reusable 3D models is therefore key to reducing the design time of the product development process. In this paper,we review the state of the art with regardtoflexibility and reusability in parametric surface-based models. We identify gaps in the field and determine the principle aspects in CAD development workflows which influence flexibility and reusability. We aim to expand the field of knowledge and establish a foundation for future research into the development of a surface-based modelling methodology