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

Hybrid deflection prediction for machining thin-wall titanium alloy aerospace component

Machining of aerospace structural components involves many thin-wall rib and flange sections. These thin-wall sections are dictated by design consideration to meet required strength and weight constraints. These components are either forged or cast to the approximate final shape and the end milling process is used to finish the parts. Alternatively, the component is machined from a solid block of material by end milling with roughing and finishing cuts. During machining, the cutting forces cause deflection of the thin-wall section, leading to dimensional form errors that cause the finished part to be out of specification. In this thesis, a new methodology for the prediction of wall deflection during machining of thin-wall feature is presented. The new methodology aims to increase the efficiency on modelling the deflection prediction in machining thin-wall component. The prediction methodology is based on a combination of finite element method and statistical analysis. It consists of a feature based approach of parts creation, finite element analysis of material removal and statistical regression analysis of deflection associated with cutting parameters and component attributes. The model is developed to take into account the tool-work geometries on material removal process during machining process. Mathematical models are developed for the wall deflection correlated with cutting parameters and component attributes. The prediction values have been validated by machining tests on titanium alloys parts and show good agreement between simulation model and experimental data. In addition, the cutter compensation method derived from the deflection prediction values can be used to reduce the magnitude of surface error, thus improving the component accuracy for machining thin-wall feature. By adopting the cutter compensation method, only one machining pass is required to machine the thin-wall feature. This compares favourably to the current practice in step method which requires many machining passes. All research results have been derived for four different cases of typical aerospace component, but it is shown that these results can be applicable for other component shape and materials. To assist commercial applications, a customized computer program has been developed for the hybrid model. The computer program is an integrated data exchanges between modules upon users input on the design information and machining parameter for automatically generate the solid model, material removal model and FEM analysis. The new method is able to reduce the analysis time from weeks to hours

Simulation-Based and Data-Driven Approaches to Industrial Digital Twinning Towards Autonomous Smart Manufacturing Systems

A manufacturing paradigm shift from conventional control pyramids to decentralized, service-oriented, and cyber-physical systems (CPSs) is taking place in today’s Industry 4.0 revolution. Generally accepted roles and implementation recipes of cyber systems are expected to be standardized in the future of manufacturing industry. Developing affordable and customizable cyber-physical production system (CPPS) and digital twin implementations infuses new vitality for current Industry 4.0 and Smart Manufacturing initiatives. Specially, Smart Manufacturing systems are currently looking for methods to connect factories to control processes in a more dynamic and open environment by filling the gaps between virtual and physical systems. The work presented in this dissertation first utilizes industrial digital transformation methods for the automation of robotic manufacturing systems, constructing a simulation-based surrogate system as a digital twin to visually represent manufacturing cells, accurately simulate robot behaviors, promptly predict system faults and adaptively control manipulated variables. Then, a CPS-enabled control architecture is presented that accommodates: intelligent information systems involving domain knowledge, empirical model, and simulation; fast and secured industrial communication networks; cognitive automation by rapid signal analytics and machine learning (ML) based feature extraction; and interoperability between machine and human. A successful semantic integration of process indicators is fundamental to future control autonomy. Hence, a product-centered signature mapping approach to automated digital twinning is further presented featuring a hybrid implementation of smart sensing, signature-based 3D shape feature extractor, and knowledge taxonomy. Furthermore, capabilities of members in the family of Deep Reinforcement Learning (DRL) are explored within the context of manufacturing operational control intelligence. Preliminary training results are presented in this work as a trial to incorporate DRL-based Artificial Intelligence (AI) to industrial control processes. The results of this dissertation demonstrate a digital thread of autonomous Smart Manufacturing lifecycle that enables complex signal processing, semantic integration, automatic derivation of manufacturing strategies, intelligent scheduling of operations and virtual verification at a system level. The successful integration of currently available industrial platforms not only provides facile environments for process verification and optimization, but also facilitates derived strategies to be readily deployable to physical shop floor. The dissertation finishes with summary, conclusions, and suggestions for further work

Razvoj jezika za 2D parametarsko geometrijsko modeliranje

Rezime: Globalizacija savremenog tržišta zahteva proizvodnju sve složenijih proizvoda, sa velikim brojem varijanti projektnih rešenja, radi prilagođavanja specifičnim zahtevima krajnjeg potrošača. Konkurencija na svetskom tržištu, posebno izražena u mašinogradnji, vazduhoplovnoj industriji, industriji motornih vozila, elektronskoj i sličnim industrijama, zahteva stalno povećanje kvaliteta proizvoda, smanjenje cena, smanjenje vremena izlaska proizvoda na tržište i fleksibilnu proizvodnju. Posmatrano sa tehničko-tehnološkog aspekta, uslov opstanka na tržištu je stalno uvođenje novih tehnologija, kao što su: programabilna i fleksibilna automatizacija, kompjuterski integrisana proizvodnja i novi koncepti, kao što su agilni proizvodni sistemi, inteligentni proizvodni sistemi i slično. Parametarsko projektovanje ima mogućnost kontrole modela parametarski definisanim „vodećim” dimenzijama, kao i uvođenja nedimenzionih geometrijskih i drugih ograničenja. Parametar kao informacija koja u potpunosti određuje model proteže se kroz sve nivoe sistema, a savremeni CAD/CAM sistemi imaju dvosmernu asocijativnost (izmena parametra na nekom nivou – modelu izaziva promenu na svim ostalim nivoima – modelima). Promenom vrednosti parametara koji definišu geometriju, automatski se menja i putanja alata, što znači da se na ovaj način može ostvariti brza izmena CNC programa – za delove, koji su geometrijski i tehnološki slični, ili – za nove varijante prizvoda. Na osnovu referentnog modela predstavnika grupe realizuju se eksplicitni modeli pojedinih članove grupe promenom vrednosti parametara modela.Abstract: The globalization of today’s market requires the production of increasingly more complex products, with a large number of variants of design solutions, in order to accommodate the specific requirments of the end customer. Competition in the global market, especially strongly expressed in mechanical engineering, aviation industry, industry of motor vehicles, electronics and related industries requires steadily increasing product quality, reducing prices, reducing the time – to market and flexible production. Being seen from the point of technical and technological aspect, condition of survival on the market is: constantly introducing new technologies as programmable and flexible automatization, computer integrated manufacturing and new concepts such as agile production systems, intelligent production systems and similarly. Parametric designing has the ability to control the model parametrically defined as "major" dimensions, as well as introducing no-dimensional geometric and other restrictions. Parameter as information which fully defines model, is extending through all levels of the system and advanced CAD/CAM systems have bidirectional associativity (changing parameter art some level causes a change in the model for all other levels – models). By chaning the values of parametres that define the geometry, automatically is, changing the tool path, which means that in this way is possible to achieve rapid shift of CNC programs, for the parts that are geomtry and technologically similar or for new variants of products. Based on the reference model as representative of the group, we can see that an explicit models of individual members of the group are realising by changing the values parameters of model

An automated method mapping parametric features between computer aided design software

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonEnterprise efficiency is limited by data exchange. A product designer might specify the geometry of a product with a Computer Aided Design program, an engineer might re-use that geometry data to calculate physical properties of the product using a Finite Element Analysis program. These different domains place different requirements on the product representation. Representations of product data required for different tasks is dependent on the vendor software associated with those tasks, sharing data between different vendor programs is limited by incompatibility of the vendor formats used. In the case of Computer Aided Design where the virtual form of an object is modelled, no standard data format captures complete model data. Common data standards transfer model surface geometry without capturing the topological elements from which these geometries are constructed. There are prescriptive data representations to allow these features to be specified in a neutral format, but little incentive for vendors to adopt these schemes. Recent efforts instead focus on identifying similar feature elements between different vendor CAD programs, however this approach relies on onerous manual identification requiring frequent revision. This research develops methods to automate the task of mapping relationships between different data format representations. Two independent matching techniques identify similar CAD feature functions between heterogeneous programs. Text similarity and object geometry matching techniques are combined to match the data formats associated with CAD programs. An efficient search for matching function parameters is performed using a genetic algorithm that incorporates semantic data matching and geometry data matching. A greedy semantic matching algorithm is developed that compares with the Doc2vec short text matching technique over the API dataset tested. A SVD geometric surface registration technique is developed that requires fewer calculations than an equivalent Iterative Closest Point method

An Architecture for Universal CAD Data Exchange

Parametric feature-based CAD data exchange is one of the most important open problems in solid modeling. The problem is significant and challenging both scientifically and commercially. In this paper we present a very general outline of the Universal Product Representation (UPR) architecture, which provides universal support for all data levels employed by today's CAD systems. The architecture has been implemented with successful results