Desktop virtual reality interface for computer aided conceptual design using geometric techniques

Data exchange between different computer-aided design (CAD) systems is a major problem inhibiting information integration in collaborative engineering environments. Existing CAD data format standards such as STEP and IGES enable geometric data exchange. However, they ignore construction history, features, constraints, and other parametric-based CAD data. As a result, they are inadequate for supporting modification, extension and other important higher-level functionality when accessing an imported CAD model from another CAD system. Achieving such higher-level functionality therefore often requires a time-consuming, error-prone, tedious process of manually recreating the model in the target CAD system. Based on techniques adapted from programming language research, this paper presents an approach to exchanging parametric data between CAD systems using formally-defined conversion semantics. We have demonstrated the utility of our approach by developing a prototype implementation that automates the conversion of 2D sketches between two popular CAD systems: Pro/ENGINEER and SolidWorks. We present examples showing that our approach is able to accurately convert parametric CAD data even in cases where models were constructed using operations from the source CAD system that have no direct counterpart in the target CAD system. Although the case study focuses on 2D interoperability, our approach provides formal foundations for supporting 3D and semantic interoperability between CAD systems.

A virtual reality (VR) interface to a feature-based computer-aided design (CAD) system promises to provide a simple interface to a designer of mechanical parts, because it allows intuitive specification of design features such as holes, slots, and protrusions in three-dimensions. Given the current state of a part design, the designer is free to navigate around the part and in part cavities to specify the next feature. This method of feature specification also provides directives to the process-planner regarding the order in which the features may be manufactured. In iterative feature-based design, the existing part cavities represent constraints as to where the designer is allowed to navigate and place the new feature. The CAD system must be able to recognize the part cavities and enforce these constraints. Furthermore, the CAD system must be able to update its knowledge of part cavities when the new feature is added. In this paper, (i) we show how the CAD system can enforce the aforementioned constraints by exploiting the knowledge of part cavities and their adjacencies, and (ii) present efficient methods for updates of the set of part cavities when the designer adds a new feature.

Extended-Reality Technologies: An Overview of Emerging Applications in Medical Education and Clinical Care.

This study examines the potential of computer-aided design (CAD) systems equipped with artificial intelligence (AI) in reducing the workload of dental technicians. We aimed to compare the accuracy and design time of crowns designed using conventional CAD with those designed using AI-equipped CAD. Abutment tooth models of a maxillary right second premolar (FDI classification #15) and a maxillary left first molar (FDI classification #26) were mounted on a dental model to form the master model. Stereolithography data were acquired using an intraoral scanner, and five dental technicians designed one crown each for #15 and #26 using both conventional and AI-equipped CAD systems. With the #15 and #26 crowns, six measuring points were established for comparing the accuracy of the occlusal surfaces and design time of the crowns designed by the two CAD systems. The occlusal surfaces were also compared for the buccal and palatal sides. The accuracy of the occlusal surface was 275.5 ± 116.8 µm and 25.7 ± 13 µm for the conventional CAD and AI-equipped CAD systems, respectively. For the buccal and palatal surface comparisons, the conventional CAD system revealed larger misfits on the palatal side for both #15 and #26, with significant differences observed. No significant differences were noted with the AI-equipped CAD system. The AI-equipped CAD resulted in significantly faster design time for both #15 and #26. The AI-based CAD system significantly reduced design time and enabled the fabrication of uniform crowns regardless of the dental technician's experience and skill.

This paper describes computer-aided design for quality — a new, cost-effective methodology for designing high-quality, manufacturable products using computer-aided design (CAD) systems. Traditionally, CAD systems have been used to simulate a producT's characteristics for a given set of values for the design parameters. Thus, designers could study the effects of design choices on a producT's quality before production started. Recent advances in computer hardware technology have given CAD systems increasingly complex and accurate simulation capabilities, permitting simultaneous examination of the effects of changes in many design parameters. But CADQ goes a step further. It provides powerful, statistical, model-fitting methods and optimization techniques that extend the traditional use of CAD systems. Given a set of quality-performance measures, a designer now can interactively pursue a producT's optimal design, while considering manufacturing constraints and characteristics of the customers' environment. Through a case study, we show the application of CADQ to integrated-circuit design.

Hand-drafted print, sketching and hand modeling were the standard for building designs before the advent of computer aided design (CAD) systems . Nowadays CAD systems are better understood, their adoption increased until the 2D, 3D CAD system and the virtual reality became the norm. Their natural evolution has given rise to a new and more complex generation of building design tools known as building information modeling, or BIM. There is insufficient clarity about what BIM is, although this is improving, and there is much shared understanding. There is agreement that BIM is not just software. BIM is not just CAD, or geometric data. BIM is a collaboratively generated and maintained, data rich, information source for the life of the design process and beyond. In this paper , we present briefly the greatest value derived from BIM in the use and maintenance of buildings and the use of TRNSYS with BIM.

An evaluation of the relationship between management practices and computer aided design technology

Future prospects of computer-aided design (CAD) – A review from the perspective of artificial intelligence (AI), extended reality, and 3D printing

The everchanging technological and digital landscape of the Product Design and Product Design Engineering industry now requires graduates to have a wider range of skills and software knowledge. In particular, there is a need for enhanced skills focused on engineering computer aided design (CAD), virtual reality, 3D visualisation and rendering/animation. This has resulted in graduates requiring a more detailed and rigorous CAD and 3D visualisation syllabus to prepare them adequately for industry. With the increased pressures on delivering a wider range of software teaching alongside a greater range of hardware, the need for a good grounding and understanding of 2D/3D engineering CAD competencies is essential. Subsequently we have identified the need for enhanced engineering CAD teaching and learning within the higher education setting especially within the first-year product design curriculum. As such, there is the need to challenge established pedagogy and delivery methods with regards to CAD tuition in order to explore new delivery methods and alternative educational paradigms to allow educators to equip engineers and designers for future industry requirements. To enhance the CAD skills of product design students, the product design academic team at Nottingham Trent University have sought to accelerate the learning of core 2D/3D engineering CAD competencies within first year students by providing an accelerated learning program focussed on SolidWorks. This paper explores and reflects on the development of a ‘CAD Bash’, an accelerated teaching block of 2D/3D engineering CAD, utilizing SolidWorks and delivered in week two of the first year product design students higher education journey. Sixty-Two BSc Product Design first year students undertook eight 1.5-2-hour sessions over the course of a 15-hour accelerated synchronous teaching block during a single week. CAD Bash synchronous teaching was also supported by asynchronous content in the form of pre-recorded videos and prepared worksheets/guides. Prior to commencing ‘CAD Bash’, each student completed a Pre-CAD Bash skills audit to ascertain the student cohorts’ current knowledge/understanding of software programs, situated within Engineering CAD, such as SolidWorks. This survey helped inform the tutors on student prior knowledge allowing adjustments to the level of learning/content delivered. A Post-CAD Bash skills audit was then collected, providing insight into the effectiveness of the accelerated teaching block, thus informing CAD tuition for the remainder of the academic year. This paper also presents student feedback and the findings from CAD Bash to demonstrate the effectiveness and impact of an accelerated CAD teaching block focused on fundamental engineering CAD competencies. Finally, this paper will demonstrate how the delivery of an entire term’s worth of CAD tuition within a single week period not only prepared students better for future CAD learning but has also created room within the CAD syllabus to teach a wider range of software in more depth. Subsequently this has enhanced our entire three-year CAD syllabus for product design students and positively impacted student skill level thus providing greater placement and graduate opportunities in the future.

Nowadays, companies are developing more and more collaborative projects, and hence the need to exchange data with many partners, contractors, subcontractors, suppliers, and customers. So, to establish successful collaborations, they must ensure the relevance, coherence, and especially the security of exchanged data. But the Computer-Aided Design (CAD) systems still have gaps that need to be corrected in order to improve the productivity of the design process: they offer few solutions to maintain data consistency within the digital model. Adding to that poor management of changes, the user has to manage the consequences of each change manually. This research explores the role of mates’ assembly, as defined in CAD systems, as a key to maintaining the links between parts in the assembly. In this work, we propose the CAD Assembly Management Model that is based on reference elements, in order to maintain mates between CAD entities when a part is modified by a partner and then reinserted into the assembly CAD, and then propagate changes.

A case is made that introducing CAD-based geometry prematurely in the aircraft design process actually hinders multidisciplinary design. Consequently, a design process which allows a designer to quickly build and analyze aerospace configurations without CAD or computational meshing specialists is proposed. This allows higher fidelity analyses to be applied at conceptual design and decreases the turnaround time for trade studies and optimizations. The basic premise of conceptual geometry modeling is presented and discussed. Key features and capabilities which are essential for a successful geometry modeler are identified. Desktop Aeronautics' conceptual geometry modeler, RAGE, is described, with emphasis on recent progress and advances in the tool. A preliminary graphical-user-interface is presented along with an application programming interface. Extensibility of the RAGE modeler is discussed along with the importance of this feature. The applicability of RAGE to simple trade studies is demonstrated in an example problem. The precision of the RAGE modeler is also demonstrated on a complex aircraft design. Future plans for the geometry modeler are also discussed. I. Background In the conceptual phase of aircraft design, there is often a wide range of geometric configurations that the designer wishes to consider, analyze, and assess. A designer’s intuition and creativity are crucial to a successful conceptual design, yet are easily inhibited by the modeling and analysis process itself, particularly if high-fidelity analysis is warranted. If the time between inception and assessment of a candidate design is relatively long, a designer may be forced to limit the number of concepts considered. New data revealed in a design iteration may suggest or require significant changes to the geometry configuration. Since the majority of considered design configurations will eventually be discarded, an ideal conceptual design process should involve a highly efficient and easy to use geometry modeler. Significant changes should be allowed without tedious re-work of the geometry model. Exporting the model for analysis should require little effort and have the capability to be automated. Therefore, any modeling application used in this process should be flexible and not restrict the designer’s choice of user interface, analysis method, and design optimization environment. Most current design processes in the aerospace industry rely heavily on computer-aided-design (CAD) applications. As a general design tool, CAD is a powerful geometry modeler capable of precisely representing practically any shape. Unfortunately, this generality is realized at the cost of requiring specialized training to efficiently and effectively use the software. Also, a CAD model is often not easily modified, especially if significant re-work of the geometry is necessary. This can lead to the premature freeze of an aircraft design due to employing excessively high-fidelity geometry modeling too early in the design process. Parametric CAD modeling could address this issue, but creating a well-designed parametric CAD model is difficult. Not only does it require an extremely skilled operator, but also the designer must have some insight into what parameterization may ultimately be desired. Modifying a parametric CAD model is often more difficult than modifying a conventional CAD model. Significant changes, such as adding or removing cross-sections, may invalidate the parameterization in some cases. In most organizations, CAD modeling (whether it be parametric or conventional) is often assigned to a dedicated CAD specialist. Since the conceptual designer is usually not a CAD specialist, the latter must communicate his design intent to the former, often using sketches, dimensions, and word of mouth. When the CAD specialist interprets the sketches, any part or detail not precisely defined usually requires judgment and artistic license. This interpretation may result in loss of design intent and indeterminate iteration between the CAD specialist and designer to obtain a satisfactory result. Because this process is iterative, CAD operators often must recreate similar geometry

The profile-based features of a mechanical computer aided design (CAD) system commonly have complicated shapes because of the guide curve, which is free-form type. However, while considering interoperability between different CAD systems, due to this kind of free-form guide curve, it is difficult to represent the corresponding feature shape in another CAD system, for example, ship CAD systems usually use relatively simple shape primitive to represent shape. Thus, in this paper, we propose a straightforward algorithm to represent profile-based features that is based on guide curve approximation using line and arcs segments. In addition, the solid alignment and filling operation are also given to complete the process of solid model reconstruction, and we use several test cases to demonstrate the effectiveness of the proposed method.

Die-casting is one of the methods used to produce a large number of components with a good surface finish by injecting cast alloys into a metal mould under high pressure. The design of a die-casting die requires human expertise and is normally performed by trial and error, which leads to monetary and time losses. Automation at the initial die design stage would result in higher productivity and would reduce the production lead time. Decisions regarding the number of cavities, the layout pattern and the placement of cavities in die-casting are critical for die design and manufacturing. This paper presents research work on a system for computer-aided cavity layout design for die-casting dies. The proposed system consists of three modules: (1) determination of number of cavities; (2) selection of layout pattern; and (3) placement of cavities in the die base. It enables die designers to generate a cavity layout design automatically from a computer-aided design (CAD) file of the part with little information provided manually. The optimal number of cavities is determined by considering economic, technical, geometrical and time limitations, followed by the selection of a layout pattern. Thereafter, cavities are placed in the die base. The developed system depends on a database of die-casting machines and materials along with a knowledge base of die design. This system has been tested on a number of die-casting parts and results have been found to be along the lines of those obtained by the industry. The proposed system is more comprehensive than those presently available and is a step in the right direction for design-manufacturing integration for die-casting.

One way to enhance students’ ability to visualize 3-D objects is to make their experience of the objects, while learning, as realistic as possible. However, in general, it is very difficult to clearly describe to students a 3-D object and the spatial relationship between the object components, without using a physical mockup. Physical mockups take a lot of time to construct, especially for more complex objects. As a result, graphics educators have started to use 3-D computer-aided design (CAD) tools to help students understand the spatial relationships between objects. However, CAD tools only allow students to examine 3-D models from outside flat computer monitors. In other words, the models and the viewers are in different realms. Using traditional CAD tools, students cannot view models with natural stereoscopic vision. Virtual reality (VR) is a computer technology of simulating or replicating a physical environment to give users a sense of being there, taking control, and physically interacting with the environment (Ausburn & Ausburn, 2004). VR technology breaks down barriers between humans and computers by immersing viewers in a computer-generated stereoscopic environment. With advances in hardware and software, most PC computers now have the capability to support VR use. Thus, VR has now become an affordable visualization tool that can be used in classrooms. As Ausburn and Ausburn (2004) indicated, there is a significant opportunity to expand and explore the use of VR in classrooms. Research suggests that VR is an effective tool that enhances learning in areas such as engineering (Sulbaran & Baker, 2000). In addition, VR engages the intellectual, social, and emotional processes of learners. The impact of VR is due to its ability to encourage interaction and ability to motivate learners (Winn et al., 1997). Salzman (1999) found that VR applications in education depends on VR features, class contents, students’ characteristics, and students’ prior experiences. The emphasis of engineering graphics education has been placed on design, problemsolving, presentation, and communication skills. Three dimensional spatial visualization ability is the core requirement for successfully developing those skills. The use of VR may also represent an effective strategy that supports the development of spatial skills. It is important to combine exposure to VR models with activities such as sketching or drawing as a means for developing a capacity for visual imagery and creativity (Deno, 1995; Devon et al., 1994; Sorby, 1999). Sorby (1999) explained that in most cases, graphics curricula begin with multi-view sketching/drawing and then move to pictorial sketching. However, this

SUMMARY In this paper the basic ideas behind an original computer-aided design (CAD) system for designing electric machinery is described. The framework in which all modules are implemented is a powerful interactive graphics system. The user thus continuously maintains control over the entire design through graphical communication. Because the CAD system is essentially conceived as a closed loop process, it supports a flexible and progressive design, allowing many trials-and-errors. Basically, the CAD system comprises two nested loops. In the outer loop, the adaptive modelling process, the geometry of the machine is controlled. The resulting geometric model maintains a dual representation of the machine. The boundary representation accepts all graphical actions of the interactive drafting system and guarantees compatibility with external systems through standards. The material region representation, on the other hand, is required for the purpose of calculation. The geometric model is hierarchically organi...