Our rapid prototype of damaged systems project seeks to provide a technology for allowing engineers to build demonstration prototypes of damaged products from analysis post-processing data. Most commercial finite element programs do not have a capability to construct deformed geometry at conclusion of an analysis simulation. It is therefore not presently possible to build prototypes of predicted states of a product as the result of being subjected to simulated adverse environments. Our approach is to reverse engineer a description of a deformed finite element mesh into a stereolithography format for prototyping using a selective laser sintering (SLS) machine. This stereolithography file can be generated from deformed surface node information as well as from a reconstructed surface defined by inspection data. We are developing software to allow users to represent a part or assembly in a deformed condition. The resulting representation can also be used to create simulated x-rays of a damaged or deformed configuration for comparison with experimental test results or field data. This allows engineers to benchmark their analysis methods and provide increased understanding of analysis results through enhanced visualization. The process of reverse engineering 'in-use' or damaged products allows for a more refined inspection and comparison of imperfect parts. It addresses the issue of whether or not a part will still work when subjected to certain environments or scenarios. Answers to this question can be found using our model reconstruction technique that represents an 'as-built' engineering model configuration. An additional feature of this reverse engineering process is product benchmarking and closer engineer/manufacturer interactions.
Two main problems currently face the developers of reverse engineering systems. The first is the time consuming digitization of 3D data. The second is the conversion of copious amounts of 3D digitized data into a concise data format exportable to CAD/CAM packages. Reverse engineering can be described as the automatic resolution of these problems. By combining the use of both a CCD camera and a 3D laser scanner, these issues can be tackled. The CCD camera is used to locate the object in the scan space, so that the laser scanner path can be programmed. Also, preliminary segmentation of the 2D image can be sued to identify individual surface segments to which a 3D laser scanner can then be directed to digitize. This extracted information can then be exported to a CAD/CAM package for the manipulation by the end user.
We describe an approach for representing an object parts by using its surface curvatures and curve tangent fields. The part representation is based on a set of 12 primitive volumes called geons. The convex edges and the compatibility between the curves guide to infer the geon type. This approach constitutes the first stage of an object recognition systems. In this system, range image data is used as the input, and part-based descriptions are built and matched to 3D object models for recognition. Segmentation and identification of the object parts are based on the RBC theory and 3D properties embedded in the range image. We do not make simplifying assumptions such as the availability of perfect line drawings. Definitions of geometrical constraints are introduced in order to infer the geons from the range image. A method for identifying the parts as one of the twelve 3D part primitives based on differential geometry is then presented. We show that range images are more suitable for geon type recognition than line drawings. The considered features give a unique and natural description to each geon.
This paper describes a method for recovering volumetric shape descriptions of 3D objects from range image. The models of shape primitives are superquadrics. The model parameters defined the shape are obtained by using genetic algorithm. The fitting energy evaluated the difference in both depth form the object center and the distribute of the normal vector between input range image and the model surfaces. When the next generation is made the model parameters are independent each other, so the crossover is applied each parameter independently. In order to overcome the local minima problem, we employ a mutation strategy and a elitist preserving strategy. After the model parameters are obtained, the remained parameters are set. We applied the proposed method to recover nondeformed superellipsoids from synthetic range image.
Laser range sensors measure the 3D coordinates of points on the surface of objects. Range images taken from different points of view can provide a more or less complete coverage of an object's surface. The geometric information carried by the set of range images can be integrated into a unified, non-redundant triangular mesh describing the object. This model can then be used as the input to rapid prototyping or machining systems in order to produce a replica. Direct replication proves particularly useful for complex sculptured surfaces. The paper will describe the proposed approach and relevant algorithms, and discuss tow test cases.
A new automated inspection algorithm of rapid prototyping parts using a 3D laser range sensor is described. The input to the program is a series of trimmed NURBS saved in an IGES format or an STL file and an unordered series of measurements produced by a 3D optical sensor. The output is an inspection report indicating the level of discrepancy between the measured points and the model. Using a color scheme, an operator can rapidly identify problems in the rapid prototyping process and validate if the produced part is conform the intended design. At the base of the method, a new robust correspondence algorithm which can find the rigid transformation between the tessellated model of the part and the measured points, is presented. This method is based on a least median square norm capable of a robustness of up to 50 percent. The robustness of the method is essential since one cannot guarantee that in practice, all the points in the measured set belong to the model. These types of algorithms are usually quite costly in computational complexity, but we will show that one can speed-up these algorithms by using the well-known iterative closest points algorithm and a multi-resolution scheme based on planar surface tessellation and voxels.
A commercial scanner provides economical and extremely accurate images. This paper discuses the scanner and how it is used in the CGI RE1000 reverse engineering and inspection system. The RE1000 complements existing laser, CMM, and x- ray technologies. The RE1000 provides greater accuracy, captures complete internal geometry, and is automatic. For opaque, machinable parts less than 1000 cubic inches, the commercial scanner and CGI RE1000 system produce the best alternative for capturing accurate, internal and external geometry.
In certain automated inspection systems, computer controlled sensors are required to move arbitrarily close to the objects under inspection, whose geometries and positions may be unknown. There exists a potential for collisions which can cause damage to the sensor and the objects. A method based upon two representations is presented which ensures collision-free motions of the sensor and positioning apparatus. The sensed environment is modelled as a discrete volumetric grid called a voxel map, which is incrementally maintained as range data is acquired. The sensor and all moving attachments are modelled as sets of spheres. The method provides a conservative underestimate of the minimum distance between the surfaces of the sensor system and all workspace obstacles within a known error bound. The conditions are derived for which a continuous collision-free trajectory exists between two configurations. These are two operational modes where collision avoidance is useful. In direct teleoperation mode, the operator has joystick control over the position of the sensor, and potential collisions are detected and averted in real-time. In autonomous mode, the sensor path is planned automatically, and collision-free motions are generated by invoking the collision detection method within an enumerative search routine. The method has been implemented and tested using a scanning laser range camera as the sensor and a Puma 560 manipulator as the positioning apparatus.
A STEP interface specification for the exchange of inspection plans and inspection data is being developed and implemented as a prototype application. It enables electronic data exchange and speeds up the flow of information in product development. This work is done within a research project by a consortium of five companies and a research institute and supported by a number of car manufacturers and suppliers.
The roofing tile is a very technical mechanical product. It allows a global recovery of the roof, with a defined design, with elementary components, with a limited weight, allowing a capability for stacking, and with specific technical characteristics. This paper shows first proposes a functional approach and CAD parametric mode. Then we show how to build the roofing tile shapes form the information obtained with the 3D digitizing system, through pro-engineer CAD software. Then, we also describe the methodology adopted for tiles description, from user values and scanning values.
The industry-led, international intelligent manufacturing systems (IMS) program provides a special vehicle for joint research and development between government, industry and academia in the United States, Canada, Japan, Australia, and Europe. Since its beginning in 1989, the IMS program has progressed through a feasibility phase which demonstrated that international legal barriers, trade issues, and intellectual property problems could be overcome. The program is constructed to provide higher quality design, customized products, shorter delivery cycles and lower costs. Interactions between partner companies have led to new business opportunities for mutual profit and some claim to have learned strategic information about their international competitors. The IMS program is growing through the participation of hundreds of corporate and university partners who share responsibilities in specific projects and jointly reap benefits for their manufacturing products and processes. The logic for choosing or not choosing the IMS mechanisms will be discussed and R and D projects will be identified.
Solid freeform fabrication (SFF) technologies have exploded exponentially since the early 1980s. One manifestation of this growth is a proliferation of new SFF processes and variations. A review of currently developed SFF processes is presented, and future trends are discussed.
The stereolithography (SL) process has benefited from many advances in the last four to five years. These include new resins with reduced shrinkage and curl distortion, enhanced software, and improved scanning techniques. One can produce highly accurate parts for most dimensions with a few mils of the design value as shown in numerous accuracy and benchmarking studies. SLA systems use a laser beam focused to a spot size of 200-250 micrometers . This limits the range of applications where SL can provide accurate models to parts which do not contain very small features i.e. wall thickness values less than about 300 micrometers . Industries that manufacture products involving components with small features include electronics and medical. In this presentation we describe an extension of the SL technology to applications involving small features. This capability is achieved by reducing the laser focal spot size in an SLA-250 to 75 micrometers . The technological principle behind the spot size reduction is described in the representation, together with process issues and applications of the technology.
The main objective of this paper is to present the first results of a quality insurance study about the global 'CAD/stereolithography/vacuum casting' process. The first experiments are mainly related to stereolithography. The significant parameters concerning dimensional and geometric accuracy of the parts are highlighted. A Taguchi approach allowed to build an experiment procedure. The results are presented and the conclusion allows to deduce concrete elements on part positioning in the stereolithography machine chamber for high quality parts.
Computer modeling and simulation are increasingly used to replace or compliment physical prototypes during product design and development. Computer models, called virtual prototypes, can be used to create realistic images of potential products, complete with color, texture, and lighting effects. For products which have not yet been computer modeled, a physical prototype can be digitized to acquire the object shape. Before colors and textures can be applied, the scattered digitized data must be approximated with a continuous mathematical surface. This paper presents a method for approximating 3D digitized data with a triangular mesh surface. The method requires three steps: data thinning, mesh generation, and mesh optimization.
Composite materials are comprised of two or more constituents possessing significantly different physical properties. Due to their high strength and light weight, there is an emerging trend to utilize composites in the automotive industry. There is an inherent link between component design and the manufacturing processes necessary for fabrication. To many designers, this situation may be intimidating, since there is frequently little available understanding of composites and their processes. A direct results is high rates of product scrap and rework. Thus, there is a need to implement a systematic approach to composite material design. One such approach is quality function deployment (QFD). By translating customer requirements into design parameters, through the use of heuristics, QFD supports the improvement of product quality during the planning stages prior to actual production. The purpose of this research is to automate the use of knowledge pertaining to the design and application of composite materials within the automobile industry. This is being accomplished through the development of a prototype expert system incorporating a QFD approach. It will provide industry designers with access to knowledge of composite materials that might not be otherwise available.
Computerization has come to our society rapidly in recent years. In particular, most processes of production are now automated in industrial fields. Owing to this computerization, even in fields of design which require imaginary processes, it is also being done. Thus, may professional designers are forced to design new products in restricted environments such as CAD systems. Today, many designers generate prototype shapes of products with actual objects like clay. It is the best method to design a product full of originality. However, it is difficult to convert the actual model to CAD data using even the latest tools and CAD systems. Our team has developed 3D shape modeler (3DSM). The 3DSM can generate the lost entities from measured data of an actual model. This system provides an interactive interface to generate the geometry of lines, planes and filet entities. ALso, as this systems is equipped with a stereoscopic display and a 3D mouse, it provides users with 3D environments. Thus, users can get a sense of the designed shape in the display.
Based on the latest development in particular in CAD/CAM, rapid prototyping, reverse engineering and inspection, rapid product development involves more and more new technologies. The integration of these different systems around common and consistent information models appears now as a main issue to get the best profit from these technologies. The issue of information models to be used in this area has appeared from the beginning and several format such as the STL format were proposed to be able to communicate between these system. The number of different existing formats, the performance as well as the accuracy of these models push today to develop new standard information models and technologies. In that way, STEP is clearly identified as a main integration technology to be applied in rapid product development. STEP has already become an international standard and was adopted by main industrial sectors to build their own integration strategies. The proposed paper present the objectives and specifications of an integrated rapid product development environment based on STEP technologies. The main concept and technical contents of STEP are defined, as well as the role and application of STEP in rapid product development.
Software tools for designers are mainly based on geometry. Today, many industrial modelers have been rebuilt with C++, or any other object oriented language. This paper proposes to locate the research topics, in order to develop a functional link between project management tools, technical data management and product models. The 'design process' aspect will also be justified through the need of capitalizing designer intent and design history. This is related to different research works of Mechanical Engineering and Logistics Laboratory of Ecole Centrale Paris, and especially two PhD topics.
There are two stages in the part manufacturing life cycle, the development stage and the production stage. In the development stage, the developer tests and verifies the design, property and functionality of the part, and usually a small quality of prototypes of the part is needed. In the production stage, engineers determine the method of production and production tools may be required. in either stage, the time and cost to produce prototypes or production tools have significant impact on the success of the product in terms of sales and profits. Conventional methods of fabricating prototypes and production tools are generally expensive and time consuming. Rapid prototyping (RP) can reduce the time can cost to produce prototypes and tools dramatically. One important advancement of RP technologies is rapid tooling (RT). RT technologies produce production tools using the RP approaches. The effect of RT manufacturing industry, in particular the plastic product manufacturers. This paper will give an overview of the background and development of the RT technology and a glance at the state-of-the-art. Processes to be discussed include RTV, KelTool, QuickCast, RapidTool, Metal Coating, Metal Shell, 3D Printing, Shape Deposition Manufacturing and Laser Engineered Net Shaping processes.
Every year, a group of students from Ecole de technologie superieure (ETS) in Montreal design and build a formula-type race car and compete in the Formula SAE competition. In this paper, we examine the design and fabrication of the ir intake system, A number of constraints challenge the designers. For example, to ensure the security of amateur drivers, motors are restrained to 600 cc and a circular restriction of 20 mm in diameter is placed at the entry of the system. Under these conditions, it is important to optimize the quality of the air/fuel mixture which depends mostly on the air intake system. A theoretical analysis reduced the field of possible runner length. However, the influence of runner configuration, plenum shape and size can only be determined experimentally. Polyacrylic functional prototypes were produced and tested on a dynamometric bench. A stereolithography model representing the inner passageways of the optimal intake manifold was built and used as a positive for a polyurethane mold. A composite lamination process was used to laminate the pre-production prototype over a molded wax plug. The major advantage of this approach over craftsmanship or even machining is the time saved to make the mold and the unlimited complexity of the shape permitted by the rapid prototyping systems.
Over the last three years research at the Centre for Rapid Prototyping at the University of Nottingham has been focusing on the developing field of rapid tooling. Within this area we have been investigating the production of laminated tooling. This paper outlines the work that has been carried out to develop laminated tooling for automotive pressure die-casting applications on behalf of the United States Council for Automotive Research.
During a normal day in the life of a Rapid Prototyping (RP) service bureau, an unusual phone call came without warning. Francis Pelletier, an Architect/Digital Simulation Specialist from the Public Works of Canada in Ottawa, Ontario was on the other end of the phone, looking for someone to build an architectural model of a building setfor some renovations in the near future. The requirements were that the model needed to be made in I :200th and I :500th scale and the parts needed to be made strictly from 3-dimensional (3D) CAD data. This was so the architects working on the project could have physical scaled models with which to work with before, during and after the renovation work was done. This kind of service was not available in Canada at the time ofthe actual project. No RP service bureau in Canada was available to take on this large scale project, and complete it in a timely manner.
The goal of this paper is to present the methodology for the development of new rings, from the physical prototype built by the designer. We show the problems related to 3D shape digitizing, surface modeling from clouds of points, and the building of the different rings corresponding to the fingers diameters. The role of stereolithography is shown in a first way as a mean for the reproduction of the CAD model, and in a second way, as the link to the industrial molds for gold casting. In the second part of this paper, we propose to give some other examples of case studies to complete the application of our methodologies in the jewelry field.
At the 20th Century 'time compression' is the key word in the automotive industry to aero-space industry to fabricate functional parts. The idea from drawing board to engineering design to form near net shape functional part is the key issue. Photonics has already shown one solution in laser rapid prototyping of low cost, quick tooling of functional parts. At present the choice of materials is limited and the time to get a functional part is almost a week. The conventional rapid prototyping processes do not have just one simple single step. Effectively it has multiple stage of pre- and post-processes. The process developed at the University of Connecticut is extension of the DTM processes. In these new techniques compact, high efficient, low cost diode laser is being used as an energy source and with the development of power delivery systems processing multi- material requires not only average high power, but also high beam intensity or power density. This paper will describe the effects of powder size and laser radiation wavelength of SLS functional parts. The purpose of this study is to rapid product development of functional parts directly from metal powder from room temperature powder bed using diode laser.