COMPUTER AIDED CONCURRENT DESIGN

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1 COMPUTER AIDED CONCURRENT DESIGN H. M. G. Bártolo 1 and P. J. S. Bártolo 2 1 Department of Construction Management & Engineering, University of Reading, Whiteknights, P.O. Box 219, Reading, RG6 6AW, UK 2 Department of Mechanical Engineering, School of Technology and Management, Leiria Polytechnic, Morro do Lena, Alto do Vieiro, Leiria, Portugal Recent advances in science and technology have had a tremendous impact in design activity. The architectural design environment has been changing with the increasing demand for a rapid knowledge transfer between all the participants in the design process. The use of these technologies will lead to the development of a new designworking environment, a concurrent design process approach, where a shared understanding enhances creativity and collaboration. Computer-aided design systems help designers to fully define the shape of their design-ideas. The use of rapid prototyping techniques will enable the transformation of a geometry created during surface modelling or solid modelling into a physical three-dimensional model. Even models with complex internal geometries and small features can be easily produced. These technologies will allow not only a better management of time and costs through the design phase, but also an actual improvement in the quality of the design product. A questionnaire survey was used to investigate how these rapid prototyping technologies combined with internet facilities are applied by design practice, and how effectively they are to enhance concurrence in design. The findings suggest that design practitioners attitudes towards concurrence in design were positive but that any goodwill was impeded by a lack of knowledge in relation to the issue of rapid prototyping. Keywords: rapid prototyping, concurrent design, internet tools, communication, commitment INTRODUCTION Building design requires the collaboration of many people with different areas of knowledge, as design problems often require specialized knowledge from many different fields. Several designers, each with specific key skills, interact in the design process. Functional, aesthetic, environmental issues, etc., are each characterized by different viewpoints, goals and constraints that have to be balanced with appropriate tradeoffs. Actually, most design processes are a collaborative activity where designers from different disciplines need to communicate and interact with one another. Design representation concerns the ways designers use to externalize and communicate their images to others, in order to search for solutions. To Simon (1969), designers present implications of images, to represent a problem means to make the solution more transparent. Goldschmidt (1991) argues that sketching helps the designer to create visual displays, this way facilitating the induction of images of the entity that is being designed. On the other way, Zeisel (1981) outlines that skilled designers use three-dimensional representation more often and more quickly as the more experienced designers can quickly sketch out an idea, draw it or build a model. Bártolo, H M G and Bártolo, P J S (2001) Computer aided concurrent design. In: Akintoye, A (Ed.), 17th Annual ARCOM Conference, 5-7 September 2001, University of Salford. Association of Researchers in Construction Management, Vol. 1,

2 Bártolo and Bártolo Most designers use drawing as a vehicle for design reasoning. They also use various types of modelling techniques to predict performance such as sketches and draws of buildings plans, sections, perspectives, etc. The huge demand for additional and more accurate performance information as well as the increasing complexity of the design process, induce design teams to employ computational media as vehicles for representation and encoding of design knowledge. Moreover, in an integrated concurrent design environment, designers need to understand/interact each other by sharing common information and reaching agreements, so they must bring their own personal viewpoints to an integrated vision of the product design process (see Figure 1). Moreover, members of a design team are often scattered geographically. Therefore, it is vital to develop a new design approach to overcome the barriers posed by distance and different levels of expertise. Advanced computer design representation packages, rapid prototyping (RP) and network technology can play a key role in this new approach. This paper presents the results of a questionnaire survey, which investigated how rapid prototyping technologies combined with internet facilities are applied by design practice, and how efficiently they are to enhance concurrence in design. Client/users Collaboration Collaboration Collaboration Others Designers Collaboration Figure 1: Collaboration and mutual learning in design. COMPUTER AIDED CONCURRENT DESIGN Concurrent design (Bártolo and Galha, 2001, 2000; Pham and Dimov, 1998; ) is a systematic approach aiming to facilitate a simultaneous involvement and commitment of all the participants in the design process. This collaborative and learning process will enable a good exchange of information and an effective reduction of the time and costs of the design phase, besides conducting to an actual improvement of the quality of the design product (Bártolo and Galha, 2001, 2000). Computer-aided design systems help designers to fully define the shape of their design-ideas. With the use of computer numerical control machine (CNC) tools, these design representations can be produced with greater accuracy. However, the programming of these machines is too much time consuming, besides being more 732

3 Computer aided concurrent design suited to the machining of complex external surfaces where tool access is available. Moreover, models with complex internal geometries and small features are either very difficult or impossible to produce using CNC tools. These problems can now be overcome by the use of rapid prototyping techniques, where the geometry created during surface modelling or solid modelling is transformed into a physical three-dimensional model, by adding layers of material one on top of another until the complete model is built. Concurrence in design will particularly benefit from rapid prototyping techniques, as the prime purpose of physical prototyping is to promptly assist iterative design, enabling design participants to work with a three-dimensional hardcopy and use it for the validation of their design-ideas (Bártolo and Galha, 2001, 2000). RAPID PROTOTYPING TECHNOLOGY Rapid prototyping (Bártolo and Mitchell, 2001, 2000a, 2000b; Lee, 1999; Jacobs, 1995; Kai and Fai, 1997) is a group of processes where physical objects are quickly created directly from computer-generated models. The processes currently available are based on a layered manufacturing technology, in which models are built up as a series of horizontal cross-sections, each one being individually formed (Jacobs, 1995). RP processes are similar to two-dimensional printing systems, using both vector-based and raster-based imaging techniques (Johnson, 1994). A rapid prototyping system can be described as a sophisticated output device for computers, the three-dimensional analogue of a computer printer. Through an accurate physical model of the design object, all members of an integrated design team can touch, feel, test, evaluate and make comments and suggestions to the several aspects of a design product. These models can serve functions so diverse as: Visualization: allowing a view of what the actual model looks like Verification: confirming if features are the desired ones, besides enabling for geometric measurements Iteration: models can be created, checked and errors corrected. Successive models can be produced until a good solution is achieved Optimization, etc. Several RP processes, such as stereolithography, laser sintering, free for extrusion, lamination and droplet deposition, are commercially available producing models in different materials (Lee, 1999; Jacobs, 1995; Kai and Fai, 1997). Stereolithography is based on the principle that a photosensitive liquid resin solidifies under the influence of light, in a specific range of wavelength. The process starts with a three-dimensional computer model that is horizontally sliced into a stack of 3D cross-sections. Each slice is physically constructed by using a laser beam to solidify the top layer of a liquid resin bath. The laser beam only draws the pattern that defines the two-dimensional shape of the cross section of the object to be built. Once a single cross section is formed, a fresh layer of liquid resin is coated over the last solidified layer and the process is repeated, with the new layer adhering to the previous one. Freeform extrusion uses continuous wires of thermoplastic polymer or wax. The wire is heated and extruded through a nozzle onto a stationary platform. Computer controlled x-y motion of the nozzle traces the cross-section of each layer. 733

4 Bártolo and Bártolo Lamination systems use paper or plastic sheets coated with a thermally activated adhesive. The contour of each cross-section is cut into the sheet with a laser. Portions of the layer not belonging to the part are crosshatched, and can be broken away upon completion of the model. Each new layer is glued to the previous layer using a heated roller. Finally in the droplet deposition process a powdered material is laid in layers and a stream of binder is deposited on it in successive patterns representing the cross sections of the desired object. The binder is deposited through standard ink-jet nozzles, as are used in two-dimensional ink-jet printing. When the binder strikes the surface of the powder material and penetrates a short distance into it, the powder and binder form a composite structure in which powder particles are trapped in a matrix of binder material. The physical model is then heated to solidify the binder and strengthen the object. These machines do not involve lasers or toxic materials as some of the other RP processes, and are relatively less expensive (Carrión, 1997). They are true desktop machines that can operate in an office environment, so they can play an important role during the design process. Rapid prototyping machines, through the generation of physical models quasiinstantaneously, enable all the distinct tasks of the design process to occur almost in parallel. Moreover, the physical-design models produced by rapid prototyping will facilitate communication among all the participants (Bártolo and Galha, 2001, 2000). Any changes resulting from this communication process can automatically be solved by upgrading the CAD model, generating a new physical representation of the design product, this way facilitating further discussions and corrections of the design solution. NETWORK TECHNOLOGY Computer network technology combines power of computers and electronic communications to exchange digital information across a computer network. This new technology allows those involved in the design process, so often geographically dispersed, to interact in real time (Sariyildiz et al., 2000). The exchange of information, through the use of computer network technology, includes different types of digital media, such as text, image, video, and audio, that can be used within a single design office (local network systems such as Ethernet) or among international sites (world network systems such as Internet). Through the use of computer network systems, designers can access to buildinginformation databases, information on innovative construction technologies, CAD databases of standard details and legal and environmental information. In addition, network technology can be used by the other members of the design team, clients/users, constructors, etc., to discuss in real time design-ideas and technical, legal and environmental aspects associated with the design. The face-to face interaction necessary to create a new building can be done through the use of videoconferencing facilities. Finally, world networking systems can be used, simultaneously, for marketing research and for promoting successfully completed buildings (the web design portfolio). The association of Internet and local Ethernet network systems with rapid prototyping machines will enable to physically materialize the information that navigates through these networks (see Figure 2). 734

5 Computer aided concurrent design Design participants (design office) Design participants (geographically dispersed) CAD systems Network connections Sketches/ Drawings Digital models Model making Rapid prototyping Physical models Drafting Digitizing process (reverse design) Figure 2: The role of rapid prototyping and computer network technology in a new integrated design environment SURVEY To perceive how building design practitioners use these new technologies, and how effective they can be to achieve an effective participation of client/user and the constructor into the design process, an questionnaire was elaborated and sent to designers. This ongoing questionnaire was sent to a geographically dispersed sample of design practitioners and consists of four sections: Section 1: personal details of the design practitioners and characterization of the design firm Section 2: the CAD part, to evaluate the effective usage of CAD technologies by the design practitioners. Section 3: the rapid prototyping part, to evaluate the level of knowledge in relation to rapid prototyping, the degree of its use, and the importance of this technology to the design process. Section 4: the internet part, to evaluate the importance of this technology to the design process. The results concern the first 100 questionnaires received, from Australia, Brazil, Canada, UK, Netherlands, India, Iran, Portugal and USA (no geographical treatment of the results was performed). RESULTS On section 1, the design practitioners were asked for information on their academic degrees, professional skills and business where they worked, besides some personal 735

6 Bártolo and Bártolo details such as gender and age. From our sample of returned questionnaires, 74% are architects and 26% industrial designers, with a male percentage of 73, distributed as following: 32% (aged from 25 to 34), 34% (aged from 34 to 44) and 44% (aged above 44). Most of the answers, 70%, came from small firms with less than 50 employees, while 22% fit in companies with more than 100 employees. Section 2 relate to the use of CAD systems. The design practitioners were asked to answer several questions on these systems, to understand in what kind of situations their organizations use CAD systems, and particularly if they are used as a tool to communicate with the client/user, and what kind of difficulties were experienced. The results reveal, as expected, a generalized use of CAD systems, as 94 % of answers acknowledge its usage. Architects commonly use these systems to produce working drawings, prime presentations, design approvals, 3D renderings and animations. A great percentage of respondents, 79%, frequently use CAD systems as a tool to communicate with the client/user, 15% only occasionally use them, while 6% never used these systems. Most of the users of CAD systems (74.5%) use them to create both 2D and 3D design representations. Thus, the creation of 3D models in CAD is widespread. It is an important finding emerging from this pilot study. If designers can easily create solid models, then they own the necessary skills to use RP systems. Consequently, RP systems could be integrated into the design environment as peripheral systems, just as conventional printers are used today. In addition, a significant proportion of respondents (63.8%) have reported to experience difficulties in using CAD systems as a communication tool with client/user, corroborating other findings from research studies (NEDO, 1983). The major difficulty mentioned (40%) is related with the lack of understanding by the client/user of CAD systems and the design representations produced by them. The design practitioners were asked about their knowledge and usage of rapid prototyping in section 3. They were also invited to express their view on the potential benefits of these systems in terms of client/user involvement, quality of the design product, time to achieve a good design solution, costs, etc. Relatively to their knowledge of RP technologies, 37% claimed to know them. However, through other answers, it was found that 54% of all respondents did not differentiate between rapid prototyping and conventional CAD/CAM systems. This is an interesting finding that suggests the need to divulge RP technologies among design practitioners - possibly through the introduction of this issue in architectural curriculum, as has been done in engineering curriculum some years ago. Nevertheless, 82% of all respondents believed its introduction in the design process would be advantageous. According to the questionnaire results, the great majority of architectural firms frequently use model makers to produce their physical models, spending, in this process, too much time (between two and ten weeks) and money, depending on the complexity and size of the model. However, some architectural firms (7%) claim to use the services of rapid prototyping manufacturing firms to produce their models. The main benefits of the use of RP technologies in the architectural design environment, as mentioned by respondents, are indicated in Table 1. Section 4 of the questionnaire, corresponds to a preliminary study on the use of internet tools. Through this section, the design practitioners were invited to express their view on the potential benefits of these tools in the building design process. According to the questionnaire results, the great majority of architectural firms 736

7 Computer aided concurrent design frequently use both local and world network systems through the design process (52%). In addition 77% of the respondents claimed to use internet facilities to communicate with clients/users, and 72% declared that internet has changed the design process. The main advantages and disadvantages of the use of internet facilities in the architectural design environment, are indicated in Table 2. Table 1: Advantages of rapid prototyping in the architectural design environment Client/user involvement Time to achieve the best solution A better understanding design at an earlier stage of the design creative process, promoting ownership and commitment Improves client/user confidence and commitment Enables to improve the number of reviews Communication between the design team, the client/user and the constructor Better communication Easier to explain design details Beneficial especially to assess the design merit of a scheme Enables a mutual learning process Quality of the design product Better end products Enables more testing The representation is close to the real building Faster Changes are made more quickly Reduces the time to achieve a solution Costs Effective cost reduction Other benefits Designers enjoyment and satisfaction Risk reduction Useful for different types of presentations Better understanding of the building design process Table 2: Advantages and disadvantages of internet facilities in the architectural design environment Advantages Disadvantages Speed of communication Improves dissemination of ideas Enables remote collaborative work Reduces human contact Dilutes creativity Security CONCLUSIONS Designers have unique communication requirements. Design requires multiple representation tools. Translations among representations are a necessary and important part of the design process. Today, design professionals have a powerful multimedia and interactive communication channel: The Internet, facilitating collaborative design and group decision-making. Direct, two-way communication of visual and spatial ideas with client/user is now possible. However, the results show that designers think that The Internet reduces creativity as it represents a deficit in human contact. 737

8 Bártolo and Bártolo The questionnaire results suggest a high level of agreement relatively to the importance of using innovative techniques to rapidly produce physical representations of the design idea, as it would enable designers to make physical models directly from CAD models. However, the lack of knowledge on RP tools by design practice is an obstacle for their widespread usage, maybe recommending their introduction into design and architectural courses. The results also outline the effectiveness of these techniques to achieve a constructive participation of the client/user in the design process, leading to an improved quality of design. This pilot study was important not only to identify the extent of the knowledge and effective application of rapid prototyping technologies by design practitioners, but also to use this exploratory study as a benchmarking tool for the next stage of the research. The next step will be to use a real architectural design environment to test the introduction of RP technologies. ACKNOWLEDGEMENTS This has been supported by the Polytechnic Institute of Leiria, for which the authors are very grateful. REFERENCES Bártolo, P.J.S and Galha, H.M. (2000) A concurrent design methodology through the use of rapid prototyping. In A. Nieuwenhuis and M. Van Ouwerkerk (eds). Research by Design. Delft University Press. Delft Bártolo, P.J.S and Galha, H.M. (2001) Concurrence in design: a strategic approach through rapid prototyping. In Proceedings of CIB World Building Congress, Wellington, NZ. Bártolo, P.J.S and Mitchel, G. (2000a) A Model for computer simulation and optimization of stereolithographic processes. In I. Campbel (ed). Proceedings of the 9 th European Conference on Rapid Prototyping and Manufacturing. University of Nottingham Bártolo, P.J.S and Mitchel, G. (2000b) A thermal-kinetic model for the study of stereolithographic processes. In T. Nakagawa, Y. Marutani, M. Imamura, M. Agarwala, A. Lightman, D. Klosterman and R.P. Chartoff (eds). Proceedings of the 8 th International Conference on Rapid Prototyping. University of Dayton Bártolo, P.J.S and Mitchel, G. (2001) Stereolithography heat-transfer and solidification simulation using the finite element method. In M.N.S. Hadi (ed). Proceedings of the 2 nd International Conference on Mechanics of Structures, Material and Systems. University of Wollongong, Carrión, A. (1997). Technology forecast on ink-jet head technology applications in rapid prototyping. Rapid Prototyping Journal Goldschmidt, G. (1991) The dialectics of sketching. Creativity Research Journal. 4(2), Jacobs, P.F. (1995) Stereolithography and Other RP&M Technologies: from rapid prototyping to rapid tooling. SME, Dearborn. Johnson, J.L. (1994) Principles of computer automated fabrication. Palatino Press. Irvine. Kai, C.C. and Fai, L.H. (1997) Rapid prototyping: principles and applications in manufacturing. Wiley. Chichester. Lee, K. (1999) Principles of CAD/CAM/CAE systems. Addison-Wesley, Reading, Ma. 738

9 Computer aided concurrent design NEDO. (1983) Faster building for industry. HMSO, London. Pham, D.T. and Dimov, S.S. (1998). An approach to concurrent engineering. Proc Instn Mech Engrs. 212, Sariyildiz, S., Stouffs, R., Ciftcioglu, O. and Tuncer, B. (2000) Future ICT developments for the building sector. In. T.M.de Jong, Y.J. Cuperus and D.J.M. van der Voordt (eds). Ways to study architectural, urban and technical design. Delft University Press, Delft, Simon, H.A.(1969). Sciences of the Artificial. MIT Press, Cambridge, MA. Zeisel, J. (1981) Enquiry by design: tools for environment behaviour research. Cambridge University Press, New York 739