A new knowledge sourcing framework to support knowledge-based engineering development

New trends in Knowledge-Based Engineering (KBE) highlight the need for decoupling the automation aspect from the knowledge management side of KBE. In this direction, some authors argue that KBE is capable of effectively capturing, retaining and reusing engineering knowledge. However, there are some limitations associated with some aspects of KBE that present a barrier to deliver the knowledge sourcing process requested by the industry. To overcome some of these limitations this research proposes a new methodology for efficient knowledge capture and effective management of the complete knowledge life cycle. Current knowledge capture procedures represent one of the main constraints limiting the wide use of KBE in the industry. This is due to the extraction of knowledge from experts in high cost knowledge capture sessions. To reduce the amount of time required from experts to extract relevant knowledge, this research uses Artificial Intelligence (AI) techniques capable of generating new knowledge from company assets. Moreover the research reported here proposes the integration of AI methods and experts increasing as a result the accuracy of the predictions and the reliability of using advanced reasoning tools. The proposed knowledge sourcing framework integrates two features: (i) use of advanced data mining tools and expert knowledge to create new knowledge from raw data, (ii) adoption of a well-established and reliable methodology to systematically capture, transfer and reuse engineering knowledge. The methodology proposed in this research is validated through the development and implementation of two case studies aiming at the optimisation of wing design concepts. The results obtained in both use cases proved the extended KBE capability for fast and effective knowledge sourcing. This evidence was provided by the experts working in the development of each of the case studies through the implementation of structured quantitative and qualitative analyses

An integrated system to design machine layouts for modular special purpose machines

This thesis introduces the development of an integrated system for the design of layouts for special purpose machines (SPMs). SPMs are capable of performing several machining operations (such as drilling, milling, and tapping) at the same time. They consist of elements that can be arranged in different layouts. Whilst this is a unique feature that makes SPMs modular, a high level of knowledge and experience is required to rearrange the SPM elements in different configurations, and also to select appropriate SPM elements when product demand changes and new layouts are required. In this research, an integrated system for SPM layout design was developed by considering the following components: an expert system tool, an assembly modelling approach for SPM layouts, an artificial intelligence tool, and a CAD design environment. SolidWorks was used as the 3D CAD environment. VisiRule was used as the expert system tool to make decisions about the selection of SPM elements. An assembly modelling approach was developed with an SPM database using a linked list structure and assembly relationships graph. A case-based reasoning (CBR) approach was developed and applied to automate the selection of SPM layouts. These components were integrated using application programing interface (API) features and Visual Basic programming language. The outcome of the application of the novel approach that was developed in this thesis is reducing the steps for the assembly process of the SPM elements and reducing the time for designing SPM layouts. As a result, only one step is required to assemble any two SPM elements and the time for the selection process of SPM layouts is reduced by approximately 75% compared to the traditional processes. The integrated system developed in this thesis will help engineers in design and manufacturing fields to design SPM layouts in a more time-effective manner

Desenvolvimento e avaliação de uma ferramenta progressiva de corte e estampagem, com sistema de roscagem, para a produção de componentes do setor elétrico

Trabalho de projeto para obter o grau de Mestre em Engenharia MecânicaA utilização de ferramentas de corte progressivo tem vindo a aumentar exponencialmente pois são ferramentas capazes de produzir uma grande quantidade de componentes num curto período de tempo. Outra grande vantagem é a sua versatilidade, pois são ferramentas que se adaptam facilmente a qualquer máquina, sendo então possível dispor apenas de uma só máquina para a utilização de várias ferramentas. A empresa JSL – Material Elétrico tem tido, ao longo dos últimos 5 anos, um aumento de vendas no que diz respeito às caixas de aparelhagem para pladur. Os componentes metálicos nela inseridos, denominados por garra de pladur, são produzidos de uma forma trabalhosa e com custos excessivos. A necessidade de melhoria deste processo tem vindo a ser demonstrada com a necessidade de uma maior produção. Este trabalho teve como objetivo desenvolver e avaliar uma ferramenta de corte progressivo capaz de produzir roscas integralmente, com base numa só operação. O processo tem como finalidade aumentar a produção de um componente metálico que pertence a uma caixa de aparelhagem para paredes de pladur. Anteriormente, era produzido através de estampagem e de uma roscagem independente com uma cadência de cerca de três vezes menos relativamente à ferramenta de corte. Utilizando uma só ferramenta de corte capaz de efetuar rosca internamente, tornou possível o aumento a produção desta peça. Desenvolveu-se a ferramenta com a sequência de operações com base na ferramenta utilizada anteriormente. Aplicou-se uma caixa de engrenagens, com base em dois fusos, que transmitem rotação aos machos. A ferramenta, ao fechar, os machos rodam no sentido dos ponteiros do relógio (atarraxar) e, ao abrir, rodam no sentido oposto para desatarraxar. Após uma série de melhorias ao projeto, realizaram-se diversas produções já com rosca. Assim, a produção diária alterou de 30000 para 115200 unidades. É de extrema importância, referir que os custos diminuíram, dado ter-se passado a utilizar apenas uma máquina.The use of progressive cutting tools has been increasing exponentially as they are tools capable of producing a large quantity of components in a short period of time. Another great advantage is their versatility, as they are tools that easily adapt to any machine, making it possible to have just one machine to use several tools. Over the last 5 years, the company JSL – Material Elétrico has seen an increase in sales in terms of drywall equipment boxes. The metallic components inserted into it, called garras de pladur, are produced in a laborious and expensive way. The need to improve this process has been demonstrated with the need for greater production. This work aimed to develop and evaluate a progressive cutting tool capable of producing threads entirely, based on a single operation. The purpose of the process is to increase the production of a metallic component that belongs to a device box for drywall walls. Previously, it was produced through stamping and independent threading with a rate of around three times less compared to the stamping tool. Using a single stamping tool, capable of internally threading, production will increase by approximately three times. The tool was developed with the sequence of operations based on the previously used tool. A gearbox was applied, based on two spindles, which transmit rotation to the taps. The tool, when closing, the taps turn clockwise (screwing) and, when opening, they turn in the opposite direction to unscrew. After a series of improvements to the project, several productions were carried out with threads. Thus, daily production changed from 30,000 to 96,000 units. It is extremely important to note that costs have decreased, as only one machine is used.N/

Plastik şekil verme proseslerinde form ve şekillendirme hatalarının telafi edilmesi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Tez çalışması kapsamında, sac metal formlama işlemlerinde geri esneme telafili form kalıp yüzeylerinin geliştirilmesi için bir tasarım yöntemi önerilmiştir. Önerilen tasarım yöntemi, formlanan parçanın geri esneme sonrası şekil bozukluğunun sonlu elemanlar yöntemiyle tahmin edilmesine dayalı olup, kalıp yüzeylerinin bu bozulmayı azaltacak şekilde değiştirilmesinden oluşmaktadır. Tez çalışması kapsamında getirilen temel yenilik; sac metal formlama işlemlerinde şekil bozukluklarının, form kalıp yüzeylerinde hata oluşmaksızın üç boyutlu olarak telafi edilmesidir. Önerilen yöntemde ilk olarak, malzeme davranışının tanımlanmasında plastisite modellerinin etkisi ele alınarak, izotrop ve kinematik pekleşme kabulü yapan kriterler çalışılmıştır. Bu kriterlerin, sonlu elemanlar geri esneme modellemesine etkileri incelenerek, hassas tahmin sonuçlarının elde edildiği modeller belirlenmiştir. Sonrasında, sonlu elemanlar modellemesinde hesaplama parametrelerinin sonuçlara etkisi deneysel tasarım yöntemi ile incelenmiştir. Önerilen yönteminin ikinci adımında, sac metal formlama işlemlerinde, formlama sonrası parçada oluşan şekil bozukluklarının telafi edilerek, formlanan parçaların istenilen tolerans boyutlarında elde edilmesi ele alınmıştır. Telafi işlemi, form kalıp yüzeylerinin malzemedeki şekil bozuklukları dikkate alınarak geliştirilmesi ile gerçekleştirilmiştir. Bu amaçla, şekil bozukluğunu üç boyutlu telafi edebilen bir yöntem önerilmiştir. Son olarak, önerilen tasarım yöntemi, literatürde geri esneme çalışmalarında sıklıkla kullanılan bir açılı kanal çekme işleminde ve endüstriyel uygulama olarak BMW binek aracında kullanılan, tavan destek sacı formlama işleminde uygulanmıştır. Önerilen yöntemin, her iki kalıp takımı için de şekil bozukluklarını başarılı bir şekilde önlediği ve literatürde yer alan yöntemlere göre daha hassas sonuçlar verdiği tespit edilmiştir.In this PhD thesis, a design methodology is proposed to compensate shape distortions in sheet metal stamping processes. The proposed design methodology depends on regenerating die surfaces by means of part shape distortion obtained by finite element modelling. The originality of this study is 3-D compensation of part shape distortions wiyhout any defects on die surfaces. Firstly, plasticity modelling of sheet metal is studied to determine the material behavior. For this purpose, isotropic and kinematic hardening plasticity models are investigated using finite element analysis to understand their effectiveness on springback prediction using design of experiments. In the second stage of the proposed methodology, compensation of shape distortions after sheet metal stamping is considered. Compensation process is applied with regenerating stamping die surfaces by consist of springback. For this purpose, a 3-D springback compensation methodology is presented. Finally, the proposed methodology is applied on a channel forming process as a literature example and BMW roof stiffener stamping process is studied as an industrial application. As a result, it is seen that the proposed method can compensate both die surfaces effectively and achieves more accurate results compare to other methods in the literature

A Methodology for Data-Informed Process Control in Progressive Die Sheet Metal Forming

This thesis investigates the coupled relationship between the strip transfer and forming operations in progressive die sheet metal forming, including the effects of the strip layout geometry, and its effect on the process speed and accuracy. Servo-actuated strip lifters and feeder are considered to assist in minimizing the dynamic response of the strip during the transfer process. A methodology is proposed for identifying suitable trajectories to prescribe the motion of active strip lifters and feeder to obtain consistent part quality without risk of process failures for a progressive die operation. Multiple iterations of a finite element (FE) model were constructed in LS-DYNA to simulate a progressive die operation. Various FE analysis techniques were used to reduce the computational cost of the simulations to allow for enough data to be generated for machine learning applications. Both explicit and implicit time-integration schemes were considered in iterations of the FE model. Both single and dual carrier strip layouts were considered. The results of the FE simulations suggest that the single carrier strip layouts produce larger predicted dynamic displacements and rotations of the work-piece as compared to the dual carrier strip layouts during strip transfer. Furthermore, the single carrier strip layout is shown to be susceptible to strip misalignment. The final version of the FE model utilized geometry based on a demonstrator tool being deployed at the Technische Universität München. A total of 1000 simulations were generated, 500 each for the ‘I’ and ‘O’ stretch-web types using a single carrier strip layout. Each simulation considered a unique permutation of control inputs sampled from the set of possible strokes rates and trajectories for the lifters and feeder. Cubic splines were used to generate the trajectories for the strip lifter and feeder by varying the position of two knots used to define the shape of the spline. The results from the 1000 simulations indicate that in general the ‘S’ stretch-web produces a larger variance in the predicted dynamic response and ‘work-piece placement as compared to the ‘I’ stretchweb. Furthermore, the stroke rate and lifter trajectory were shown to have a large influence on the overshooting of the work-pieces during strip transfer and the probability of whether tooling collisions occurred. Multiple machine learning models were trained on the data generated by the final FE model. Two types of classifiers were constructed using neural network and XGBoost architectures. The first classifier predicts whether the clearance between the strip and binder are within a specified tolerance (to prevent collision with the tooling) during strip transfer. The second classifier predicts whether the placement accuracy of the work-piece on the forming die after strip transfer is within a specified tolerance. A range of tolerances were considered when labeling the data for both classifiers. Nestedcross fold validation was used to select the hyperparameter tuning and model selection. The machine learning classifiers were used to test all possible control inputs using a ‘minimum feed clearance’ of 10 mm and a maximum ‘work-piece placement error of 0.11 mm. The maximum stroke rate at which a given pair of lifter and feeder trajectories can operate was identified for all permutations. Five permutations that achieved the highest predicted stroke rate were simulated for an additional five strokes. The classifiers showed a reasonable ability to predict the ‘minimum feed clearance’ and ‘workpiece placement in the extended FE simulations for the selected trajectories, but, was unable to account for the strip misalignment which occurred after several strokes in all simulations. This research successfully demonstrates a methodology for using machine learning models trained on FE simulations to predict process outcomes of a progressive die operation with variable feeder and lifter trajectories. The FE simulations used to train the machine learning models were generated by adopting computationally-effective FE modelling techniques in a single press stroke model. The machine learning models were shown to reasonably predict the process outcomes of novel input permutations in a multi-stroke FE simulation. One of the largest constraints in this research is the FE simulation time which limited the model complexity that could be considered in the training set generation. Furthermore, the demonstration of the machine learning predictions for a multi-stroke process was limited due to the susceptibility of the single carrier strip layout to misalign after strip progression. Future work should consider the use of dual carrier strip layouts for the generation of the training data. Alternative approaches may also be considered, such as a machine learning framework for directly predicting the forward dynamics of the progressive die operation or a co-simulation approach in which a robust controller interacts directly with the FE simulation