Product design and engineering

In the fields of industrial design and car manufacturing the creation of 3D curves plays a fundamental role within the design process: it allows the improvement of the visual appeal of artifacts, it enhances ergonomics and the product's commercial competitiveness through product differentiation. When flexibility and intuition are to be privileged it is fundamental to achieve natural, intuitive, mathematically correct, creation and modification of surfaces. The scientific aim of this research is the development of an innovative metaphor to modeling of 3D curves which maintains the natural expertise of the designer. The major contribution of this paper is the capability of the system to create and modify the curve naturally, without mathematical artifices, within the limits set by the use of Bezier curves. The proposed metaphor combines the benefits of two acknowledged techniques referred to as the Digital Tape Drawing and the Eraser Pen, which allow the real-time modification of the curve. The integrated adoption of tangible interfaces and innovative mathematical tools, combined with the adoption of semi-immersive environment and lightweight interaction devices, delivers intuitive curve creation for free-form modeling within the virtual scene. The paper describes the details of the algorithm developed and it highlights its strengths during the styling phase. © 2004 ACM.

Keywords: 3D curve generation , Computer aided styling (CAS) , Virtual environments

The use of modularity in the design of a new product or the adoption of a product platform, as the base to define new solutions within a product family, offers the company a chance to meet diverse customer needs at low cost because of economies of scale in all phases of the product's life cycle. At present, the concept of modularity in product design is becoming widely used in many industries such as automobiles and consumer electronics. However, if modularity and mass customization have attracted the interest of industries and researchers, the greatest efforts have been focused on the theoretical aspect whereas the related design support technologies have been only partially implemented. In this context, our intent is to develop highly reusable models, which are able to reconfigure themselves on the basis of new functional requirements. The proposed approach is based on the definition of what we call self-configuring components and multiple-level functions. To describe the approach, a practical example related to the design of modules for woodworking machines is reported.

Keywords: Feature-based Model , Functional Analysis , Product Configuration

Reverse engineering techniques are broadly used in the development process of products with meaningful aesthetic properties. Many stylists prefer to evaluate the product shape on the basis of a full-scale hand made physical mock-up. Such model has then to be converted into a 3D CAD model, to begin the product engineering and production processes. A critical aspect of the RE process is that the physical mock-up, made by the stylist, usually does not take into account the engineering production constraints. The surface reconstruction activity must then be followed by a modelling phase, where the engineering designer modifies the reconstructed model shape in order to make it suitable for production. At the end of this process, no matter how accurate and precise the surface reconstruction phase has been, the product model will be different from the original mock-up, and then it needs to be submitted to the stylist for the validation of its shape. For the stylist, getting used to working with physical models, the shape validation on a virtual model is not a trivial task. The objective of this research is to develop a software tool to support the identification of aesthetic and functional regions of the product model shape, that have been modified with respect to the original mock-up. The proposed approach is based on the decomposition of a 3D surface analysis problem into a simpler 2D curves analysis problem. This approach simulates the traditional method used by stylists to evaluate the quality of shapes. The implementation of the developed algorithms has been performed using a commercial software package (I-deas FreeForm by EDS/Unigraphics) and it has been successfully applied on real test cases. © 2003 Elsevier Ltd. All rights reserved.

Keywords: Physical mock-up , Product engineering , Style , Virtual mock-up

A Reverse Engineering- (RE) and Rapid Prototyping- (RP) based approach to (he development of a joystick handgrip with ergonomic features has been elaborated. The integration of Time Compression Techniques and Computer Aided Tools lead to a time-saving procedure for the design of a product whose ergonomic quality directly descends from users' sensations of comfort. The CAD model availability throughout the progressive steps of product development ensured all the potentialities of Concurrent Engineering, while Computer Aided Engineering (CAE) simulation on the definitive geometry allowed to close the Computer Integrated loop to the manufacturing process.

Keywords: Computer Aided Engineering , Design for Manufacturing , Ergonomics , Product Development , Reverse Engineering

The use of 3D tracking systems in a Virtual Reality environment may definitely change CAD interfaces and free-form surface modelling. In this paper an original method for full 3D interactive surface shaping and modifying is described. VISM (Virtual Integrated Surface Modeller) has been developed with the leading idea that 3D tracking system can dramatically speed up modelling sessions. On the opposite of a W-I-M-P (Windows-Icons-Menu-Pointer), paradigm common to most current CAD systems, VISM demonstrates that Virtual Reality devices can manage all types of surface in a unique shape generative action. Unlike "Virtual Clay" based and "Metaball" modelling techniques, VISM both wants to give to engineers and designers a more intuitive and natural tool to get 3D shapes. Based on Polhemus Fastrak and stereoscopic vision, VISM doesn't provide icons to (he designer, leading to a "null icons" and "null menu" full 3D interface. The new interface is fully implemented on bi-manual input system on top of a Virtual Reality environment. The entity grabbing is also supported by pinch-enabled gloves. The designer exploits a NURBS curve tool to deform a NURBS surface and extracts drive curve direction from his right hand movement. The curve tool may be also real-time deformed with left hand through node-control point repositioning. Furthermore the modeller is fully implemented using NURBS curves and surfaces and a fast surface-over-curve positioning and deformation has been implemented, replacing both traditional snapping and picking activities.

Keywords: 3D interface , CAD , Spatial Tracking , Surface modelling , Virtual Reality

An integrated environment based on CAD assembly software and on an Augmented Reality wearable system is used to improve the overall integration between engineering design and real prototypes manufacturing. The environment following called - Personal Active Assistant (PAA) - exploits a CAD tool connection to remarkably improve object recognition, best assembly sequence optimization, and operator instructions generation. PAA is real-time and wirelessly linked to a remote server or designer workstation where project geometric database is stored. The PAA head-mounted camera is also able to acquire the human-driven assembly sequence and check the efficiency and correctness via object recognition: an incremental sub-assembly detection algorithm has been developed in order to achieve complex dataset monitoring. On the other hand, the Augmented Reality-based assembly evaluation tool allows engineers to interact directly with the assembly operator while manipulating the real and virtual prototype components. Information from the assembly planner can be displayed, directly superimposed, on the real scene by using a see-through head-mounted display. Thus the new combined software and hardware equipment may be considered a step ahead in the support of true concurrent engineering and remote collaboration, strongly improving this latter through a better heterogeneous task integration. Several tests have been performed also to achieve personnel training and warehouse part seeking.

Keywords: Assembly , Augmented reality , CAD , Concurrent engineering , Virtual reality

In this paper the fatigue phenomena of 2024 T3 aluminium alloy were studied in terms of thermal and calorimetric effects during uniaxial cyclic loading. Thermoelastic coupling sources and dissipation were separately estimated by using infrared thermal data and a local simplified form of the heat equation. The simplifications are essentially based on the assumption that the uniaxial fatigue test remains homogeneous until a macroscopic fatigue crack occurs within the gauge section of the specimen. Heat sources were then compared to predictions derived from mechanical data by assuming a linear isotropic thermoelastic behaviour of the material and by neglecting the influence of thermomechanical couplings on the hysteresis area of fatigue cycles. © 2004 Taylor & Francis Group, LLC.

Keywords: Aluminium , Dissipation , Fatigue , Infrared thermography , Thermomechanical couplings

Recently, some web-based tools have been proposed to support both individual designer and design teams in the management of information and in assisting concurrent distributed design activities. The rationale which is often underlying such proposal is to enhance design-manufacturing engineering or product data management (PDM) systems for managing product development as a single integrated business process. The focus of this paper is on presenting a logical model which can drive the conception of tools for supporting the distributed management of design data of mechanical products (DDDM: Design Data Distributed Management). How the model can be fruitfully used to support individual/group technical activities and group organisational activities, especially in the product design review phases during the product development process, is discussed. The main functionality and the client/server architecture of one of these tools is also described, and, lastly, a case of study is reported in order to explain how the model can be applied.

The delivery of manufactured goods may be specified as a function of four independent factors. In addition to the conventionally considered invested capital I and contributed labour L, know-how and technology K has been recently recognised as an important independent input to the economic system, while tangible resources T may be introduced to provide an accounting of material and energy depletion. In this paper, sets of technology-driven developments are considered based on these four independent factors while setting aside economic, social, legal and political considerations. Eco-consistency concepts are reviewed followed by a discussion of the basic green-engineering approach to eco-design. These discussions lead to more specific issues including a focus on the clear accounting of the consumption of tangible resources. Also considered is the trade-off between sustainability costs and technology benefits to manage production and enterprise growth aiming both at ecological safety and economical return. The conclusions address development strategies that will be important in the foreseeable future. An extensive reference list has been provided for this interdisciplinary field. © 2003 Elsevier Ltd. All rights reserved.

Keywords: Eco-design , KILT-models , Method-innovation , Product-service , TYPUS-metrics

This work deals with the analysis of the API (American Petroleum Institute) normative that regards controlled volume pumps for use in the petroleum and gas industries. The API normative is utilised as an example for a generic process of understanding a normative and making it applicable inside the design process, in order to reduce the time requested to verify the compliance of the product with the standard.

A geometric primitive for CAD implementation is presented in this paper (Bèzier Neural Network BNN). It is specifically designed to reproduce geometric shapes with functional requirements such as aerodynamic and hydrodynamic profiles. This primitive can be useful when a known and well defined map between functional requirements and geometric data does not exist, and it have to be deduced by a physical or numerical experimental analysis. BNN gives rise to a typical CAD representation, a Bèzier curve, of a functional profile, once the functional parameters are supplied. In BNN the capability of neural network to approximate very complex and non-linear function has been combined with the capability of Bèzier functions to describe geometry, in a unique neural network. In this work BNN is used in the representation of aerodynamic profiles starting to their typical functional parameters: lift and drag coefficients, Reynolds number and angle of attack. BNN is tested in reproducing the wing profile of the 4-digit NACA series. The output of BNN is compared with the results of a fluiddynamic analysis performed by commercial software. © 2003 IEEE.

Concurrent Engineering methodology and process analysis and modeling showed the importance of tools that allow the designers to evaluate, from the beginning, different aspects of product definition. 3D CAD systems, simulation tools and virtual prototyping technologies can support the designer during her/his decision-making activity but, in order to provide an effective support, they must be tailored to the needs of the design process of each specific product. During last years, different types of tools appeared on the market to support this tailoring activity and to promote the development of product-dependent applications. In this paper, we have focused the attention on software tools named KAE (Knowledge Aided Engineering) development shells. Applications implemented by using this type of tools can support experts during the decision making process to evaluate alternative solutions. They provide a kernel for the integration of different technologies, and represent a basic step for the development of the product design. In this paper we present a brief overview of the architecture of a typical KAE application and we provide a survey of the most significant systems that we have developed, within different application domain, taking advantage of the KAE technology. © 2003 by Springer Science+Business Media New York.

Keywords: Feature technology , Knowledge aided engineering

Monitoring tires working conditions has proved to be very important for best aircraft ground performances. Thus, to prevent safety risks it is necessary to recognize all the parameters really affecting tires dynamic behaviour and study a proper supervising strategy, able to guarantee an easy and effective security action. It will be proved that measuring tire internal gas pressure (even with internal temperature compensation, then measuring the total internal gas mass) it is not possible to monitor accurately the tire dynamic behaviour. In this paper a new approach to design a new generation of tires monitoring system will be presented. Copyright © 2003 SAE International.

The European directive 2000/14/CE partially rules the noise impact assessment of industrial machines and equipment designated to an outdoor use in order to obtain significant mitigation strategies of sound noise. This directive has been adopted in Italy by the recent DL n° 262, 4 September 2002. This paper provides an approach for sound suppression and noise control of some moderate-sized generating set. In particular the approach described has been applied to some generating set presenting a high value of sound power in order to reduce it accordingly with the value provided by the normative. The implementation of the method described in the paper concern both the devising of new acoustical mufflers than the design of the carter and the choice of sound absorbing materials. Accordingly we have developed a numeric fluid-dynamic approach to detect the loss of head involved in the flow ducts and for reducing the Transmission Loss respecting the inlet and outlet gas pressure conditions. Furthermore we have designed several different configurations of the carter and the sound power has been checked experimentally. The results of this work proved to be suitable for designing generating sets with sound power less than the maximum provided by the normative.

Big and small administrations are more and more interested in the use of Geographical Information System (GIS) for both urban and territorial planning. In a previous research the GIS system was used as support to build a simplified acoustic model to determine the urban noise levels close to the receiver positions and to define the critical areas where the exceeding of the limits occurred. In another research, a procedure was developed in the GIS system to determine what kind of noise reduction interventions were effective and suitable to be assigned in the critical areas. In this research a new procedure was integrated in the GIS system. The procedure was able to assign a priority index to each suitable intervention previously determined. The procedure was defined according to the Italian directives, in particular, the Tuscany Region directive. The new procedure integrated in the GIS system proved to be a valid supporting tool for the decisions of the territory's administration, as it allowed them to know the order in which to realize all the interventions to perform in a certain area.

Collaborative solid modelling among distributed designers is becoming an effective chance for product design. Nevertheless the available solutions usually rely on proprietary systems and formats and do not enable heterogeneous collaboration. The overall aim of the work presented in this paper is to introduce a frame-work for heterogeneous collaboration. The proposed solution is based on the definition of an intermediate neutral modelling language capable of capturing the modelling activities carried out by distributed users. The described system is based on the XML Schema technology.

The efforts made by a company to focus on the manufacturing process to minimize production costs are not any more sufficient to launch competitive products on the market. In recent years, the industry has focused on the integration and optimization of the phases of the product development process and on the introduction of innovations in the attempt to tackle and solve the above mentioned issues. The paper presents the results of a research project whose aim is to study a methodology for the evaluation of the impact and costs related to the adoption of new and innovative technologies for knowledge and innovation management within currently implemented companies' product development processes (As-Is process).

Keywords: Knowledge management , Product development process , Product innovation , Technical creativity

We describe the current design of the European gravitational sensor (GS) for the LISA Technology Package (LTP) that, on board the mission SMART-2, aims to demonstrate geodetic motion within one order of magnitude of the anticipated LISA performance. We report also the development of a noise model used in assessing the performance and determining the feasibility of achieving the overall noise goals for the GS. This analysis includes environmental effects that will be present in the sensor. Finally, we discuss open questions regarding the GS for LTP and LISA, ground testing, and verification issues.

Commonly, during the aesthetic design process, stylists sketch features called character lines over a simple and "uninteresting" geometry (e.g. a car bonnet) in order to confer personality, emotional feeling and style. This work presents an original interface paradigm for character line sketching in a virtual reality environment. Taking advantage of the 3D interface, the feature path, also called leading line, can be directly sketched on the initial surface by realtime projection. Afterwards, a semi-transparent section is selected along the path in a interactive way and then the feature profile is sketched on this plane according the user's intention. Subsequently, by moving the virtual pen forwards along the path, the character line is generated, on the contrary if the pen is moved backwards the feature is partially erased. The distance of the virtual pen from the leading line controls, in real time, the offsetting along the path of the feature which remains consistent in style and identity. Such a system has been proven to be a powerful tool for fast expression and evaluation of ideas, which can be, in subsequent design phases, integrated with detailed surfacing applications and prototyping.

Keywords: Constrained-based design , Curve and surface design , Feature-based design , Parametric modelling

The definition of methodologies to support the development of product families is a challenging problem which has received much attention, as can be seen in the literature referenced. In this context, the configuration of solution phase is a basic task. When a company studies a new product variant it is important to evaluate, early in the process, different alternatives. The product cost can be among one of the most meaningful criteria used to determine an optimal solution. Therefore, it is advantageous to be able to estimate the cost in the design phase, where the larger part of it is committed. This work shows how a cost estimation method can be used effectively within a framework, to manage the configuration of a product variant. In more detail we describe a low-cost prototypal software system which allows the configuration of the solution and the determination of production costs related. Additionally a practical example is shown, which documents results of collaborative efforts with an industrial partner, who is a manufacturer of woodworking machines for the wood panels polishing (calibrating/sanding). To optimise results while at same time complying to the company's needs, the cost estimation tool implemented has been used in the machining operations domain.

Keywords: Cost estimation , Feature-based cad model , Modularity , Product configuration