Product design and engineering

This paper presents a plug-in, named Cloth Assembler, implemented in the framework of the Italian PRIN Project (Research Project of National Interest) VI-CLOTH (Virtual CLOTHing). The base idea is to allow the designer to interactively define/the necessary information to assemble 2D panels on a virtual mannequin and to generate the 3D physical model in its initial configuration, initial step for the garment simulation process. Starting from 2D single pieces, ClothAssembler allows a user, as a virtual tailor, to specify assembly rules among cloth panels (e.g., cut lines, dart, and buttons), insert accessories, such as zips and hooks, and, finally specify finishings on single pieces and the presence of different textile multilayer, pockets, reinforcement lines, etc. The plug-in can be easily integrated with any commercial 2D CAD system and represents the connection element between 2D cloth world and 3D physics-based modelling and simulation systems. It has been validated with three real test-cases, a T-shirt, a denim skirt, and a pair of trousers.

Keywords: Apparel design , Assembly process , CAD , Cloth models , Virtual prototyping

The aim of the paper is to make up a virtual showroom and work-through of a train model in order to allow railway companies showing new trains prototypes, in phase of concept, and present their new design in more exhaustive way than simply technical documentation. The possibility of applying Virtual Reality (VR) methodologies to make a scene more realistic as possible is a great advantage for the effectiveness of the presentation, in order to increase their competitivity. Shader technology allows the programmers to have control over shape, appearance (such as colour, lighting, reflection) and animation of objects, in order to make very realistic real-time rendering. In the paper the authors describe the use of shader technology in Virtual Design 2 (VD2) for realistic presentation of train prototypes in VR. The software VD2 is an extensive tool that allows following many phases of product development, from the creation of showroom for realistic presentations supporting shader technology to the assembly simulation or ergonomics analysis. Moreover, the possibility of interfacing with a wide range of input/output devices and the possibility to access to the API made this software to be chosen for Virtual Reality applications in the VR laboratory of the Competence Center for the Qualification of Transportation Systems founded by Campania Region (www.centrodicompetenzatrasporti.unina.it).© 2006 The Eurographics Association.

Keywords: Concept design , Shader technology , Train design , Virtual Reality

While relational simulation games have been widely used for learning activities in areas such as business, management and communication, their development in the engineering field is still very limited. In this paper a web-based simulation game was designed in order to fill this existing gap in the development of relational simulation games related to engineering aspects and in particular to the design process of complex systems. An evaluation of a first web trial competition, carried out by questionnaires, shows a satisfactory achievement of the proposed learning tool objectives. © 2006 Inderscience Enterprises Ltd.

Keywords: complex systems , engineering-design education , learning tools , simulation , web-based games

Interoperability among CAD/CAM/CAE systems is a well known problem in product design and development. At present geometrical data exchange among different software packages is usually carried out through neutral file formats (IGES or STEP) or through proprietary formats. Data exchange processes are usually afflicted by several problems, such as: information loss, redundancy, one-way data exchange and static data exchange. These drawbacks do not permit a really geometric-centric design, and even if the model is transmitted without loss of information, the exchanged data do not incorporate details such as sketches, constraints and features, which represent the designer's intent. As a result, the model can hardly be modified, and the original intent of the designer may be misunderstood. During the last five years various solutions have been proposed to solve the above mentioned problems. The aim of this work is to investigate and discuss recent research trends in this topic. © 2006 IEEE.

Hip prostheses should meet the anatomical and physiological characteristics of patients; this is the rationale for designing modular implants of different sizes. To optimize implant geometry, it is necessary to consider, not only the prosthesis component design, but also the final configuration of the implanted leg. This means the necessity to consider the specific morphological and functional condition of "that" patient and not only of "that" hip to restore, at best, limb functions. Variations in the length of the implanted limb are frequent; therefore, the variations in the three geometrical features of the hip prosthesis neck, which can affect the restoration of the anatomical symmetry of the limbs, were investigated: (i) neck lengths (Ln), between 50.5 and 64.5 mm; (ii) cervico-diaphyseal (CD) angle (γ), between 135 and 125° and; (iii) anteversion (AV) angle (β), between 0 and 15°. Adopting a three-dimensional (3D) simplified biomechanical model, the resultant load acting on the hip was estimated for each different design solution; corresponding stress distributions and contact pressures at the interface between the prosthesis head and the ultra high molecular weight polyethylene (UHMWPE) layer were evaluated by 3D finite element (FE) analyses and using the Strozzi approach. The following values have been assumed as physiological values: γ = γp = 125°, β = βp = 15° and Ln = 57 mm; it was found that to contrast limb lengthening, if the CD angle varies from 135-125° (with neck length Ln = 64.5 mm and AV = 0°), the joint resultant load decreases by 8.8% (7.2% if AV = 15°); the contact pressure decreases by 5.8%, (5% if AV = 15°); the bending moment in the stem neck increases by 10.9% (13.8% if AV = 15°) and the torque increases by 1% (12.8% if AV = 15°). © Società Italiana Biomateriali.

Keywords: Anteversion angle , Cervical-diaphyseal angle , FE , Hip prosthesis , Limb lengthening , Prosthesis neck geometry , UHMWPE wear

The paper presents the results of a research project aimed at developing an innovative system for modeling industrial products based on haptic technology. The system consists of a Computer Aided Design (CAD) system enhanced with intuitive designer-oriented interaction tools and modalities. The system integrates innovative six degrees of freedom (DOF) haptic tools for modeling digital shapes, with sweep operators applied to class-A surfaces and force computation models based on chip formation models. The system aims at exploiting designers' existing skills in modeling products, improving the products design process by reducing the necessity of building several physical models for evaluating and testing the product designs. The system requirements have been defined observing designers during their daily work and translating the way they model shapes using hands and craft tools into specifications for the modeling system and the haptic tool. The system prototype has been tested by designers who have found it intuitive and effective to use. © Springer-Verlag London Limited 2005.

Keywords: Haptic modeling , Haptics , Product design , Virtual prototyping

The paper presents the results of a research project aiming at developing an innovative framework for conceptual design of products based on innovative haptic interfaces. The framework consists of a CAD (Computer Aided Design) system enhanced with intuitive designer-oriented interaction tools and modalities. The system integrates innovative 6 degrees of freedom haptic tools for modeling digital shapes, with sweep operators applied to class-A surfaces and force computation models based on chip formation models. The system aims at exploiting designers' skills in modeling products, improving the products design process by reducing the necessity to build several physical models for evaluating and testing the product designs. The system requirements have been defined after observing designers during their daily work and translating the way they model shapes using hands and craft tools into specifications for the modeling system and the haptic tool. The system prototype has been tested by designers who have found it intuitive and effective to use. Copyright © 2006 by ASME.

The paper presents two applications of haptic technologies to demonstrate how they can increase human computer interaction during different steps of design process. The first application aims at developing a system to generate digital shapes by manipulating haptic tools that resemble the physical ones that the modelers use in everyday work. The second is focused on the use of haptic interfaces to evaluate ergonomics of virtual products control boards. We designed and developed the mentioned haptic devices; the first uses two FCS HapticMaster equipped with a innovative strong and stiff 6 DOF device carrying simulated clay modeling tools. The second is an "ad hoc" mechatronic device able to simulate some controls with rotary motions (knobs). The described haptic devices are integrated in more complex virtual reality applications; the paper describes their architecture and the methodologies proposed to simulate material shaping and ergonomic validation. The main aspects of haptic modeling and rendering are also discussed. © 2006 Elsevier Ltd. All rights reserved.

Keywords: Haptic modeling , Haptics , Product design , Virtual prototyping

A statistical approach based on the variance analysis allows to appraise the influence of the foam that covers leg impactors on results of the tests required by European New Car Assessment Program [EuroNCAP, Pedestrian Testing Protocol, Rel. 3.1.1, Gennaio, 2002] and ACEA (European Automobile Manufacturers Association) for the safety of the pedestrians in case of accident. Impactor used to evaluate the damage in pedestrian test is made by TRL and is quite similar to the structure of the human femur: it has a very complicated system to simulate the whole bone-flesh-skin apparatus and, in particular, has two layers of special Confor™ Foam CF45 Blue that has the same mechanical behaviour of human flesh; we have made a dynamic characterization of that foam at medium and high impact velocity; in order to simulate the whole leg impactor, in PamCrash environment, using the ESI formulation of the skin and using the results of characterization of all other elements with experimental tests. Experimental data coming from tests on foam have a medium value and dispersion around the mean; that dispersion can affect significantly the results of final simulation. So we have applied several statistical methods in order to optimize the final simulation results. This analysis is a part of a more complex design of experiment that analyse the difficulties when we simulate, using finite element method (FEM) simulation, the impact pedestrian-car. In problematic that is complex and not linearly influenced by many factors even a numerical simulation could be improved and optimised by statistic techniques. © 2005 Elsevier B.V. All rights reserved.

Keywords: Confor Foam , Design of experiment , Pedestrian safety

Virtual Reality (VR) technologies are becoming commonly used tools in the product development process, starting from the styling review in the conceptual design phase, until to the Digital Mock-up (DMU) validation in the advanced stages of the design process. What has not yet been sufficiently investigated is the possibility to interact with the DMU directly inside the CAD environment using 3D input devices. Although few CAD systems, like CATIA V5, have an additional module to support VR devices, in most cases it is still necessary to customize the application to obtain the functionalities desired by the user. The present paper discusses difficulties and advantages related to the integration of VR techniques and 3D input devices in CAD systems. The work has been conducted analyzing and testing the potentialities of the Unigraphics NX3 CAD environment and implementing a software plug-in that allows the user to perform such interaction tasks employing 3D input devices. © 2006 The Eurographics Association.

The paper presents a discussion of some problems related to knowledge management in product lifecycle thought treating some applications developed in different aspects of lifecycle: conceptual design, detailed design, production, selling, maintenance, diagnostic and dismissing. In these applications, we show how Knowledge management is involved in all these phases: IT proposes several methodologies and tools to represent and manage knowledge to aid expert who operates in the domains related to product lifecycle. Methodologies such as Triz can be used to assist conceptual design, while KBE systems permit to automate design procedure of numerous products. Neural networks and fuzzy logic help to select right approaches to production. The paper ends presenting some applications performed by the authors, focusing aspects related to design. © 2006 Springer.

Keywords: Knowledge based engineering , Knowledge management , PLM

The selection of modeling and machining parameters for glass mould fabrication in ophthalmic lenses production, has required the definition of a theoretical-empirical model of the ground surface in order to predict the overall geometry errors of the surface. The accurate control of the geometrical errors and of the surface texture for the mould functional surface is crucial for the subsequent polishing operation, which is responsible for the final geometry, surface finish and cost. The basic hypotheses validation has been accomplished by measuring the micro-geometric parameters P, W and R and by characterizing the macro-geometry comparing the nominal profile and the measured profile. The correspondence among theoretical hypotheses and experimental results allows realistic predictions of the attainable surface texture during a contour grinding operation and the adoption of preventive actions in order to compensate the geometrical errors due to modeling and tool path generation parameters. © 2005 Elsevier Ltd. All rights reserved.

Keywords: Brittle mode , Geometry error , Glass , Grinding , Process modeling , Surface roughness

Aim of the LISA Test-flight Package on board the LISA Pathfinder mission is to provide in-flight demonstration of some of the LISA critical technologies in achieving the free-fall condition of a LISA-like test-mass in the bandwidth from 1 to 30mHz. Accordingly, owing to high inertial loads arising during the launch phase the test-mass needs to be firmly secured to the GRS, in order to avoid collision with the surrounding electrodes and housing parts. After the launch and orbit commissioning, the test-mass must be released to floating conditions, in compliance with strict requirements of initial position and velocity, due to the low force and torque authority made available by the capacitive actuation system. The Caging Mechanism Assembly is being designed by Alcatel Alenia Space Italia and it constitutes the GRS subsystem dedicated to cage and release the test-mass. The release phase to floating conditions has been identified as critical for the entire mission, therefore a ground-based verification of such a function has been deemed necessary. The verification approach adopted is to set both test-mass and release-dedicated plunger mock-ups in representative tribological conditions of the in-flight situation. An effort is being made to build a facility that enables to characterize the momentum transfer between the two suspended bodies and verify the compliance of the design of the release-dedicated mechanism subsystem of the Grabbing Positioning and Release Mechanism of the CMA. The proposed experiment and the facility status are here presented and discussed. © 2006 American Institute of Physics.

Considering the whole product life-cycle, product model is usually defined during the design phase, given a set of requirements and constraints belonging to the same domain. The use of different manufacturing and verification technologies may, however, profoundly affect the characteristics of the product, so that a re-design phase is often necessary. In previous work, a Knowledge Based System named Design GuideLines (DGLs) was developed, aiming to help the designers make the product model compatible with the requirements and constraints of the specific manufacturing and verification domains. During the DGLs development, the possibility emerged to exploit them in order to identify possible relations among product features. This aspect seems very important, further helping the designer to better understand the consequences of the modifications suggested by the DGLs and applied to the product model during the re-design phase. The present work aims to identify these relations among product features. The result of DGLs exploitation has been critically analyzed to highlight the link between manufacturing characteristics and product features, and, further, among features themselves. Unpredictable relations among the product features, given a particular Rapid Prototyping technology as manufacturing technology, have been discovered and exploited. Copyright " 2006 by ASME.

Keywords: Fluid deposition modeling , Knowledge based systems , Process parameters , Product features , Rapid prototyping

Residual stresses develop during most manufacturing processes involving material deformation, heat treatment, machining or processing operations that transform the shape or change the properties of a material. They have a not negligible effect on the material strength, especially on fatigue. For this reason, it is important that some knowledge of the internal stress state can be deduced either from measurements or from modelling predictions. The object of this paper is forecasting the modification and the evolution that a residual stress field, originated by welding, suffers after chip-forming machining, such as milling and cutting. Numerical results have been critically compared to experimental measurements and show the potentiality but also the limitations of numerical techniques. © 2006 Elsevier Ltd. All rights reserved.

Keywords: Cutting , Finite element analysis , Milling , Residual stress , Welding

In the conceptual design, a product can be viewed as a functional net, defined in the classic active verb-object way, by mean of functional elements and links associated to the flow of energy, material and signals and link of force. In order to assure the validity of the links at different levels, in the paper the graph theory is employed to check the suitability of a functional net, treated as a collection of sub graphs, each defined on a type of link. In order to verify the functional net it is necessary to identify each subnet, characterized by the same kind of link, and check each one using a set of formal relations that represent the feature of each link. Based on these relations a set of controls have been implemented for each subnet.

Keywords: Design process , Doubt based system , Functional net , Graph theory

In the last ten years many Augmented Reality (AR) applications for Scientific Visualization have been developed, attesting the effectiveness of this technique for data visualization and interaction. In all these applications, a software framework for scientific visualization was used to process data to be visualized, while an AR system was employed to display these data within an AR context. Hence, everyone who intended to approach the development of such applications should become necessarily familiar with the scientific visualization framework and the augmented reality one. This is of course an hurdle for the applications development, and the idea behind this work is exactly to provide a software framework that simplifies the development of such applications. With this in mind, we extended an existing and powerful open source library for scientific visualization (VTK) with few but useful classes for the interfacing with an existing AR library (ARToolKit) to easily handle the video see-through and the video-tracking functionalities. The resulting software tool, called VTK4AR, can be considered as an all in one software framework specific for scientific visualization in AR. Moreover, since it is built on top of VTK, it will be possible to employ a wide range of visualization techniques in many application fields. In particular, it has been tested in two AR applications: one for displaying data relative to a CFD simulation of a flow past a helmet, and another for displaying the forming error obtained prototyping an ankle support with the incremental forming technique. © 2006 The Eurographics Association.

The present work focuses on the study of a method to acquire and formalise the design knowledge in a way usable for implementing a knowledge-based software system to support the NPC. The approach is based on the representation of corporate knowledge within a structured framework where market requirements, product specifications and functional aspects are interrelated. A hierarchical multi-level DSM structure allows representing such knowledge in a rationale manner. This paper presents the methodology to formalize the product knowledge, the used structure to define the specifications for implementing the knowledge-based product configuration system and, finally, a practical example to illustrate our proposed framework.

Keywords: Change management , Decisional process automation , Design structure matrix (DSM) , Product configuration

The majority of Virtual Reality applications developed today are either specific product oriented, not flexible enough to be implemented in every industrial design process to achieve complex real world tasks. In this context the adoption of VR systems, designed and customized on the need of the specific company, can be accepted only if it is possible to quantify the achievable benefits in terms of time, quality and cost. Our research focuses on how these benefits can be objectively measured. A benchmarking program and related metrics to explore advantages and disadvantages connected with the new design technology have been studied. Our main goal is to measure the performance of the VR-based design review processes by meaningful test cases.

Keywords: Design review , Industrial design , Virtual reality

Injection molding is a diffuse technology used to manufacture a large number of products. The molded component production chain involves many specialized "actors" employed in different companies, generally small and medium-sized enterprises. The coordination of the distributed product development team and the "vertical" and "horizontal" collaboration have to be supported by suitable methods and tools in order to minimize process iterations due to misunderstandings and errors. This paper describes the preliminary study of a methodology to implement the inter-company collaboration in the mold design context. The methodology will be based on a set of procedures, rules and tools that support the management of all mold design processes. © 2006 ISAM.

Keywords: Agile design , Collaborative design , Feature sharing