A survey on 3D CAD model quality assurance and testing

[EN] A new taxonomy of issues related to CAD model quality is presented, which distinguishes between explicit and procedural models. For each type of model, morphologic, syntactic, and semantic errors are characterized. The taxonomy was validated successfully when used to classify quality testing tools, which are aimed at detecting and repairing data errors that may affect the simplification, interoperability, and reusability of CAD models. The study shows that low semantic level errors that hamper simplification are reasonably covered in explicit representations, although many CAD quality testers are still unaffordable for Small and Medium Enterprises, both in terms of cost and training time. Interoperability has been reasonably solved by standards like STEP AP 203 and AP214, but model reusability is not feasible in explicit representations. Procedural representations are promising, as interactive modeling editors automatically prevent most morphologic errors derived from unsuitable modeling strategies. Interoperability problems between procedural representations are expected to decrease dramatically with STEP AP242. Higher semantic aspects of quality such as assurance of design intent, however, are hardly supported by current CAD quality testers. (C) 2016 Elsevier Ltd. All rights reserved.This work was supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund, through the ANNOTA project (Ref. TIN2013-46036-C3-1-R).González-Lluch, C.; Company, P.; Contero, M.; Camba, J.; Plumed, R. (2017). A survey on 3D CAD model quality assurance and testing. Computer-Aided Design. 83:64-79. https://doi.org/10.1016/j.cad.2016.10.003S64798

A Modified Reverse Engineering Approach Using Bezier Curve Approximation

Reverse Engineering is a process of re-producing existing parts by obtaining digital models using a special data taken from the original parts using specific techniques. It can be used to redesign existing parts either due to lost data or the parts are no longer available. In this paper, surface modelling technique using special data taken from CMM (Coordinate Measuring Machine) was employed to redesign a candle holder. Specific MATLAB code was generated to model the data taken from the surface of a candle holder made of glass. Bezier curve technique was implemented in this research to model the curve of the outer surface of the candle holder. Various orders of Bezier curves were discussed and used to give better approximation of the original data curve with error percentage monitoring each time. The thickness of the candle holder was reduced from 5mm to 3mm and the volume reduction was calculated. The amount of reduction in the glass volume when reducing the thickness was found to be 210mm3. In addition, the amount of increase in the area of glass section was calculated to be 138.5mm2. This reduction gives a better vision of the amount of glass saved using this procedure. Two different shapes were found and plotted by varying the control points coordinates

Reverse engineering approach for precise measurement of the physical attributes related to the geometric features of agricultural products

The characteristics related to the physical properties of agricultural products can be considered when designing and sizing machinery systems/equipment used in agricultural production. Agricultural products as biological/organic materials have several unique characteristics, which set them apart from conventional engineering materials such as steel and plastic based materials, in the context of inner structure and product geometry/shape. Agricultural materials have heterogeneous inner structures and irregular shapes cultured by nature. Most especially, the irregular shape of most agricultural products complicates their physical and engineering analysis. Therefore, precise description of the irregular product geometry/shape is significant for any related analyses used in both product quality evaluation and design of agricultural machinery systems. This study describes a reverse engineering application procedure for precise description of the physical attributes related to geometric features (size, shape, volume etc.) of the agricultural products under consideration. In the study, a three-dimensional (3D) laser scanner has been utilised and 3D digital model data of the selected sample agricultural product (Pecan) processed in the virtual environment through 3D scanner software and 3D parametric solid modelling design software has been collected. After 3D solid models were created, some of the physical attributes related to geometric features of the agricultural products were measured precisely and realistic virtual 3D computer aided design (CAD) data was provided for deeper rheological investigation such as structural deformation, fluid dynamics (flow) and heat transfer analyses of the products by means of computer aided engineering (CAE) techniques. Finally, a comparative deformation simulation case study was concluded. This study contributes to further research into the development of agricultural machinery and equipment through the utilisation of reverse engineering and CAD tools

Aerospace Medicine and Biology. A continuing bibliography with indexes, supplement 151

This bibliography lists 195 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1976

Software tectonics

Thesis (Ph. D. in Design and Computation)--Massachusetts Institute of Technology, Dept. of Architecture, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 365-370).The resent shift of attention in the architectural discourse towards issues of ecological design, coupled with the undeniable role of computation, has already cast a new operative role to the notion of environment. Instead of being the passive, conceptualized or historicized context of an architectural object, environment is quite literally becoming the object of design itself. We are moving away from the imposed-preconceived Cartesian object which negotiates through its boundaries its presence within its immediate context. The discipline is already considering an architecture in which architectural form is only an instance of a designed environment. In many respects, this new understanding of environment aspires to be actively designed as a closed system of constant transformation, an autonomous milieu of exchange at all scales and all levels between substances, properties or qualities. The object of investigation in Software Tectonics is how technologies of design and construction allow newly forming propositions about the role of environment in the discipline to become operational tactics in the design practice. SOFTWARE TECTONICS proposes 3 design research projects. VSpace is a computer drawing application for designers. Unlike traditional CAD systems that work primarily by representing boundaries (B-reps), VSpace derives form by the representation and direct manipulation of properties (P-reps) in space. Boundaries and Properties here are considered simultaneously in the same design environment. Castit is a multi axis, Computer Numerically Controlled device that prints 3D objects by dynamically mixing at least two distinct but chemically compatible materials. Dynamic mixing allows for gradient transitions between two or more materials, resulting in objects with anisotropic material properties. CHUNK aims to eliminate a joint as a third mediating member between two building elements with an area of gradient transition. Conceived as a "dynamic insulation" architectural skin, this building technology project challenges the multi-trade and multi-component tectonics of dominant late-industrial building manufacture.by Alexandros Tsamis.Ph.D.in Design and Computatio

Investigation and development of an advanced virtual coordinate measuring machine

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel UniversityDimensional measurement plays a critical role in product development and quality control. With the continuously increasing demand for tighter tolerances and more complex workpiece shapes in the industry, dimensional metrology often becomes the bottleneck of taking the quality and performance of manufacturing to the next level. As one kind of the most useful and powerful measuring instruments, coordinate measuring machines (CMMs) are widely employed in manufacturing industries. Since the accuracy and efficiency of a CMM have a vital impact on the product quality, productivity and manufacturing cost, the evaluation and improvement of CMM performance have always been important research topics since the invention of CMM. A novel Advanced Virtual Coordinate Measuring Machine (AVCMM) is proposed against such a background. The proposed AVCMM is a software package that provides an integrated virtual environment, in which user can plan inspection strategy for a given task, carry out virtual measurement, and evaluate the uncertainty associated with the measurement result, all without the need of using a physical machine. The obtained estimate of uncertainty can serve as a rapid feedback for user to optimize the inspection plan in the AVCMM before actual measurement, or as an evaluation of the result of a performed measurement. Without involving a physical CMM in the inspection planning or evaluation of uncertainty, the AVCMM can greatly reduce the time and cost needed for such processes. Furthermore, as the package offers vivid 3D visual representation of the virtual environment and supports operations similar to a physical CMM, it does not only allow the user to easily plan and optimise the inspection strategy, but also provide a cost-effective, risk-free solution for training CMM operators. A modular, multitier architecture has been adopted to develop the AVCMM system, which incorporates a number of functional components covering CMM and workpiece modelling, error simulation, inspection simulation, feature calculation, uncertainty evaluation and 3D representation. A new engine for detecting collision/contact has been developed and utilized, which is suitable for the virtual environment of simulated CMM inspections. A novel approach has been established to calculate errors required for the error simulation, where the data are obtained from FEA simulations in addition to conventional experimental method. Monte Carlo method has been adopted for uncertainty evaluation and has been implemented with multiple options available to meet different requirements. A prototype of the proposed AVCMM system has been developed in this research. Its validity, usability and performance have been verified and evaluated through a set of experiments. The principles for utilising the AVCMM in practical use have also been established and demonstrated. The results have indicated that the proposed AVCMM system has great potentials to improve the functionalities and overall performance of CMMs.ORSAS and the School of Engineering and Design of Brunel University

Dynamic analysis of assembled structures with nonlinearity

Imperial Users onl