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This article reports the results of a research aimed to evaluate the ability of a haptic interface to improve the user experience (UX) with virtual museum systems. In particular, two user studies have been carried out to (1) compare the experience aroused during the manipulation of a 3D printed replica of an artifact with a pen-like stylus with that aroused during the interaction (visual and tactile) with a 3D rendering application using a haptic interface and PC monitor, and (2) compare the users’ perceived usability and UX among a traditional mouse-based desktop interface, haptic interface, and haptic gamified interface based on the SUS scale and the AttrakDiff2 questionnaire. A total of 65 people were involved. The considered haptic application is based on the haptic device Omega 6 produced by Force Dimension, and it is a permanent attraction of the Museo Archeologico Nazionale delle Marche. Results suggest that the proposed haptic interface is suitable for people who commonly use mouse-based computer interaction, but without previous experience with haptic systems, and provide some insights useful to better understand the role of haptic feedback and gamification in enhancing UX with virtual museums, and to guide the development of other similar applications in the future.

With the rising importance of CAD models for product development and the recent strong promotion of hybrid geometric modeling from within the industry, the focus of teaching methods in current CAD education, as practiced in most institutions of higher education, needs to be reconsidered. From a pedagogical point of view, this situation represents a challenge, as it requires new, innovative teaching methodologies which advance the development of competency going beyond basic domain knowledge and skills limited to operating a CAD system. In this paper, a new and innovative direction for CAD education is offered, which is based on the integration of traditional teaching methods with an educational approach using negative knowledge. Central aspects of framework development and concept translation are presented together with promising results obtained through a multi-method oriented empirical study of this newly developed and now fully implemented approach.

Advancing formative assessment in MCAD education is an important but difficult problem. Success in this endeavor requires feature-based MCAD model assessment to consider the quality of a model from various viewpoints. That includes the absolute criteria that are associated with technical domain knowledge and also criteria related to model deficiencies. For the latter, this entails assessing the results of wrong or inappropriately applied system commands, and of partial or entire modeling strategies. Here, an approach that combines the perceptual abilities, creativity, and domain knowledge of the human user with the computational power of current desktop computing has great potential to contribute to solving the problem. The aim of the current paper is two-fold. Firstly, it presents a novel approach to analyzing feature-based characteristics of MCAD models, an approach that is aimed at advancing formative assessment in the educational context. This approach is based on visual analytics and efforts to combine visualization, human factors, and data analytics. Secondly, it reports on the technical architecture and concrete implementation of a newly developed visualization environment for a software tool to enable and put into practice this novel MCAD model assessment approach. The development of this new visualization environment is based on an advanced visualization pipeline that employs radial visualization, while supporting dedicated user interaction techniques to facilitate analytical processes.

With a steadily increasing use of CAD systems within digital prototypes in product design and development, the capacity to create viable geometric models that can be used in various computer-aided engineering processes is becoming an indispensable necessity. However, with the current trend of commercial CAD systems increasingly to promote hybrid geometric modeling environments, this requirement poses a new challenge for education, as it requires a teaching strategy that goes beyond the sum of subject learning in surface modeling and solid modeling. In this paper, a novel teaching approach is introduced, which integrates negative knowledge as one crucial element in combination with traditional teaching methods to support competency development that reaches beyond the acquisition of basic modeling skills and domain knowledge.

Today’s product development processes rely on Mechanical Computer-Aided Design (MCAD) systems that implement a geometric-centered perspective in design. The development of long discussed feature-based MCAD has not yet led to systems that truly support semantic and functional representation of features, which hampers also the use of these models for functional reasoning. This paper investigates the present feature-based MCAD limitations. It illustrates, through simple examples, how to use ontological analysis and feature re-classification to introduce software extensions in existing MCAD that achieve a newer level of semantic representation of features, and enhance the cognitive understanding of the final model. The proposal also shows how to automatically validate these features from the functional viewpoint.

Purpose – High pressure die casting is a widely used industrial process to manufacture complex-shaped products in light alloys. Virtual prototyping techniques, especially numeric-based simulations of the casting process, allow the die filling process to be evaluated and help faster optimization of the gating system, which is the most critical element of the mould. The purpose of this paper is to present a four step approach to design optimal moulds taking advantage of the simulation tools. Design/methodology/approach – No formalized method to design an optimal gating system is available yet and the majority of the studies aim to optimize existing geometries or to choose from alternative solutions. Rather than optimizing the geometries of predefined designs by running attempt trials, the proposed approach defines a procedure to position cavities, gating systems and, finally, to determine the whole mould geometry. Findings – The approach is demonstrated through three different industrial applications. The design of a six-cavity mould for gas cooking burners is reported at first. Then, two test cases, a cup and a radiator, are reported for showing different arrangements of the gating system. The reached quality of the mould design has been assessed using metallographic analyses of the casts. Originality/value – The design of a mould is strictly correlated to its product and mainly based on a trial-and-error approach. Numerical simulations offer a powerful and not expensive way to study the effectiveness of different die designs and filling processes. The paper proposes a structured approach for the definition of the gating system. It ultimately leads to improvements in both product quality and process productivity, including more effective control of the die filling and die thermal performance.

In this paper a framework based on the concept of functional dimensioning features is presented. It is aimed at supporting a methodological approach to explicit modeling with a focus on issues related to its use in MCAD education and practice. The proposed framework is based on the assumptions that shape, dimensions, and required manufacturing precision of a mechanical component are designed to fulfill specific functionalities. Principle formation and development regarding geometric entities and associated functional meaning are approached with an orientation on the concepts and definitions introduced by the GPS system of standards. Application of the GPS standards requires that dimensions and tolerances of the functional elements are specified within the nominal representation of a part or component. The traditional method of representing such information is a 2D technical drawing. However, explicit modeling provides new perspectives and opportunities for approaching 3D modeling, since it allows ...

Traditional computer-aided design (CAD) education in mechanical engineering still remains a major challenge today both in industrial settings and in academia. As in many other CAD-related engineering disciplines there are several shortcomings to be surmounted in the dissemination and development of procedural knowledge and skills in the form of know-how related to the operation of CAD systems. Unfortunately current educational philosophy does not offer a pedagogy providing sufficient strategic knowledge and understanding to enable students to use CAD systems as intended – that is as knowledge-intensive design and communication tools to properly develop and convey design intent. However apart from knowing what to do there is another important aspect to strategic knowledge which is frequently over-looked and ignored in research today and that is knowing how to avoid serious mistakes. This is a central quality of professional expertise which is commonly referred to in the literature as negative knowl...

3D optical scanning systems are used more and more for quality control purposes. The effective utilization of such systems needs an efficient virtual planning of the product acquisition viewpoints. Literature shows how 3D CAD product models can be used as reference in order to manage the verification process and as a basis for the computation of the optimal viewpoints. However, in the mechanical field, a variety of inspection tasks is experienced by engineers involved in the quality control process: GD&T verification, production phases control such as sheet metal cutting, evaluation of aesthetic appearance of parts, global shape deformation measurement and specific point deviations assessment. This leads to the necessity of flexible view planning approaches which adapt to the specificity of the required inspection task. The present work targets the development of a comprehensive view planning approach in which several algorithmic options are triggered by the product features to be inspected. Algorithms have been implemented in a prototypal software system which has been experimented as an off-line application to provide inputs to a multi-axis degree of freedom robot arm mounting an optical 3D scanner. Two test cases from die casting and automotive fields are presented. They show the computation of acquisition poses in a suitable sequence and efficiency in the obtained results.

Mechanical product quality is strongly influenced by the respect of Geometrical Tolerances (GT). On the other hand, competitiveness forces companies to improve their productivity making the tolerance verification process faster and faster and more flexible. Component control by 3D full field optical digitizing systems and specific CAD-based (Computer Aided Design) inspection software tools are important steps forward for the achievement of the above-mentioned goals. However, the adoption of these solutions in industry is minimal. This may be due both to technological factors, i.e. poor systems usability, and organizing factors, i.e. clear separation between design department and quality control department. In this context, our research aims at developing a new easy to use CAD-based tool for simulating, driving and optimizing the GT inspection process. Once a component has been digitized, the developed software system automatically realizes the tolerances virtual control. Hence, the designer can prescribe tolerances, pilot the measurement system and verify the component conformity. The implemented tool is based on Full of Information (FoI) CAD models, which contain tolerance data, linked to a knowledge database, where measurement strategies and verification rules are stored. A computation engine calculates the measurement paths and performs the tolerances verification. The prototypal system has been tested on different real cases. Experimental results showed high performances in terms of timesaving and robustness.

In the context of styling products development, it is well known that sketches are the most immediate and used means for the ‘external representation’ of the industrial designers' intentions; the designer, however, also needs physical full-scale models, in order to evaluate the aesthetic solution. Reverse engineering techniques support the transformation of the physical mock-ups in digital ones, in order to perform the engineering developments. The observation of the design phases highlights the need to study new methodologies and computer-based tools, in order to simplify the reverse engineering process and to improve the quality of the final result. The conversion from real to virtual can be time consuming and strongly critical, in terms of product aesthetic and functional contents preservation. The process can be affected by several misunderstandings in the communication of the design values from the designer to the product engineers. In this paper, we propose a method for the formalization and recogni...

Design intent representation is a well-known issue in the MCAD domain, and is related to the readability, alterability, and usability of CAD models. The recent widespread introduction of functionality and commands in modern CAD systems, aimed at facilitating explicit modeling, introduces not only a new modeling paradigm supplementary to the feature-based approach, but also a new perspective on how the design intent can be captured and represented. Taking into account the traditional method of communicating design intent with functional dimensioning in mechanical drawings, in this paper a novel approach is presented, aimed at translating this traditional design intent representation from 2D into 3D. Objectives are directed towards the specification and implementation of dimensioning correspondence mapping and the identification as well as examination of shortcomings in current systems. This should help direct future improvements aimed at supporting 3D dimensioning within 3D explicit modeling systems.

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 callself-configuring componentsandmultiple-level functions. To describe the approach, a practical example related to the design of modules for woodworking machines is reported.

Despite international efforts to support specification and exchange of CAD data through acknowledged standards and data interfaces, in practice several problems still remain. One type of problem is related to the reconstruction and verification of CAD data containing defects. Major problems causing such defects are related to differences in the internal modeling accuracy of systems. Generated models that sometimes contain degenerated edges and faces having either almost zero length or zero area exacerbate the situation. Defects in the topology and / or the geometry of such geometric models have a severe impact on computer-aided post-design processes such as finite element analysis, STL file generation, tool path generation, etc. In the meantime, until improvements can be made in the processes that generated those corrupted CAD data, correction of possible errors in CAD data can be achieved by introducing an intermediate post-processing step aimed at reconstructing an error-free, valid solid model. Within the given scope of this paper, we introduce and investigate the application of a face-sewing operator, which can be applied to CAD data based either on surface models or on solid models. Operation and quality of the model reconstruction are determined by the tolerances of spatial model space points located on the face boundaries and their distances apart. Due to the use of reference kernel architecture featuring a Brep scheme within an integrated multi-dimensional topology supporting both surface models and solid models, a CAD data interface based on a standard data exchange format and an internal translator that classifies, converts and correlates pure geometric entities, sub-setting geometric entities and topological entities, open and highly flexible system architecture in respect to considered CAD data and geometric models can be maintained.