Littérature scientifique sur le sujet « Geometrical deviation model »
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Articles de revues sur le sujet "Geometrical deviation model":
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Tabar, Roham Sadeghi, Kristina Wärmefjord et Rikard Söderberg. « A new surrogate model–based method for individualized spot welding sequence optimization with respect to geometrical quality ». International Journal of Advanced Manufacturing Technology 106, no 5-6 (19 décembre 2019) : 2333–46. http://dx.doi.org/10.1007/s00170-019-04706-x.
Résumé :
AbstractIn an individualized shee metal assembly line, form and dimensional variation of the in-going parts and different disturbances from the assembly process result in the final geometrical deviations. Securing the final geometrical requirements in the sheet metal assemblies is of importance for achieving aesthetic and functional quality. Spot welding sequence is one of the influential contributors to the final geometrical deviation. Evaluating spot welding sequences to retrieve lower geometrical deviations is computationally expensive. In a geometry assurance digital twin, where assembly parameters are set to reach an optimal geometrical outcome, a limited time is available for performing this computation. Building a surrogate model based on the physical experiment data for each assembly is time-consuming. Performing heuristic search algorithms, together with the FEM simulation, requires extensive evaluations times. In this paper, a neural network approach is introduced for building surrogate models of the individual assemblies. The surrogate model builds the relationship between the spot welding sequence and geometrical deviation. The approach results in a drastic reduction in evaluation time, up to 90%, compared to the genetic algorithm, while reaching a geometrical deviation with marginal error from the global optimum after welding in a sequence.
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Huang, Zhicheng, Jean-Yves Dantan, Alain Etienne, Mickaël Rivette et Nicolas Bonnet. « Geometrical deviation identification and prediction method for additive manufacturing ». Rapid Prototyping Journal 24, no 9 (12 novembre 2018) : 1524–38. http://dx.doi.org/10.1108/rpj-07-2017-0137.
Résumé :
Purpose One major problem preventing further application and benefits from additive manufacturing (AM) nowadays is that AM build parts always end up with poor geometrical quality. To help improving geometrical quality for AM, this study aims to propose geometrical deviation identification and prediction method for AM, which could be used for identifying the factors, forms and values of geometrical deviation of AM parts. Design/methodology/approach This paper applied the skin model-based modal decomposition approach to describe the geometrical deviations of AM and decompose them into different defect modes. On that basis, the approach to propose and extend defect modes was developed. Identification and prediction of the geometrical deviations were then carried out with this method. Finally, a case study with cylinders manufactured by fused deposition modeling was introduced. Two coordinate measuring machine (CMM) machines with different measure methods were used to verify the effectiveness of the methods and modes proposed. Findings The case study results with two different CMM machines are very close, which shows that the method and modes proposed by this paper are very effective. Also, the results indicate that the main geometrical defects are caused by the shrinkage and machine inaccuracy-induced errors which have not been studied enough. Originality/value This work could be used for identifying and predicting the forms and values of AM geometrical deviation, which could help realize the improvement of AM part geometrical quality in design phase more purposefully.
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Nguyen, Dinh Son, Frederic Vignat et Daniel Brissaud. « Geometrical Deviation Model of product throughout its life cycle ». International Journal of Manufacturing Research 6, no 3 (2011) : 236. http://dx.doi.org/10.1504/ijmr.2011.041128.
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Polini, Wilma, et Andrea Corrado. « A Unique Model to Estimate Geometric Deviations in Drilling and Milling Due to Two Uncertainty Sources ». Applied Sciences 11, no 5 (24 février 2021) : 1996. http://dx.doi.org/10.3390/app11051996.
Résumé :
Industry 4.0 involves the use of information and communication technologies to transform industry by intelligent networking machines and processes. The availability of big data sets from manufacturing and inspection allow for developing new and more accurate simulation models. This involves the development of new machining simulation models to consider the geometrical deviations of the workpiece due to the machine tool, the part datum surfaces and the fixturing equipment. This work presents a model that kinematically correlates the locator uncertainty, the form deviation on the part datum surface in contact with the locators and the volumetric uncertainty of the machine tool, with the geometric deviations of a surface due to a drilling or milling process. An analytical model was developed in a Matlab® file to simulate the surface geometrical deviations from nominal during drilling or milling. It is new as regards the state of the art because it takes into account two sources of uncertainty. This numerical approach allows for avoiding experimental tests, with a resultant saving of time, energy and material. It was applied to drilling, face milling and contouring processes. It was proved that machine tool volumetric uncertainty influences the form deviation of the machined surface, while the locator configuration and the datum form deviation affect the orientation of the machined surface, as should be in reality. The proposed model allows us to take into account geometrical deviations of the part datum surfaces of 0.001 mm, location deviations in the locators of ± 0.03 mm and machine tool positional and rotational uncertainties of 0.01 mm and σd=0.01∗π180 mm, respectively.
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Sánchez-Sola, José Miguel, Moisés Batista, Jorge Salguero, Alvaro Gómez et Mariano Marcos Bárcena. « Cutting Speed-Feed Based Parametric Model for Macro-Geometrical Deviations in the Dry Turning of UNS A92024 Al-Cu Alloys ». Key Engineering Materials 504-506 (février 2012) : 1311–16. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.1311.
Résumé :
This work reports on the results of a study of different macro-geometrical deviation parameters, such as Straightness (SD), Parallelism (PD) and Circularity (CD) as a function of cutting speed (v) and feed (f) of dry turned UNS A92024 (Al-Cu) cylindrical bars. The results obtained have allowed establishing exponentials parametric model for predicting these deviations as a function of those cutting parameters. As a consequence of that, geometrical surfaces SD(f,v), PD(f,v) and CD(f,v) have been developed for this alloy. These surfaces allows determining marginal curves for specific v and f values, respectively, out the parameter ranges employed. So, macro-geometrical deviations can be predicted through this model for v and f values out of those considered in the study for each alloys.
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Dash, Satabdee, et Axel Nordin. « TOWARDS REALISTIC NUMERICAL MODELLING OF THIN STRUT-BASED 3D-PRINTED STRUCTURES ». Proceedings of the Design Society 3 (19 juin 2023) : 3591–600. http://dx.doi.org/10.1017/pds.2023.360.
Résumé :
AbstractThe as-built geometry and material properties of parts manufactured using Additive Manufacturing (AM) can differ significantly from the as-designed model and base material properties. These differences can be more pronounced in thin strut-like features (e.g., in a lattice structure), making it essential to incorporate them when designing for AM and predicting their structural behaviour. Therefore, the aim of this study is to develop a numerical model with realistic characteristics based on a thin strut-based test artefact and to use it accurately for estimating its compressive strength. Experiments on test samples produced by selective laser sintering in PA 1101, are used to calculate geometrical deviations, Young's modulus, and yield strength, which are used to calibrate the numerical model. The experimental and numerical results show that the numerical model incorporating geometrical and material deviations can accurately predict the peak load and the force-displacement behaviour. The main contributions of this paper include the design of the test artefact, the average geometrical deviation of the struts, the measured material data, and the developed numerical model.
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Zhao, Binbin, Yunlong Wang, Qingchao Sun, Yuanliang Zhang, Xiao Liang et Xuewei Liu. « Monomer model : an integrated characterization method of geometrical deviations for assembly accuracy analysis ». Assembly Automation 41, no 4 (26 juin 2021) : 514–23. http://dx.doi.org/10.1108/aa-11-2020-0165.
Résumé :
Purpose Assembly accuracy is the guarantee of mechanical product performance, and the characterization of the part with geometrical deviations is the basis of assembly accuracy analysis. Design/methodology/approach The existed small displacement torsors (SDT) model cannot fully describe the part with multiple mating surfaces, which increases the difficulty of accuracy analysis. This paper proposed an integrated characterization method for accuracy analysis. By analyzing the internal coupling relationship of the different geometrical deviations in a single part, the Monomer Model was established. Findings The effectiveness of the Monomer Model is verified through an analysis of a simulated rotor assembly analysis, and the corresponding accuracy analysis method based on the model reasonably predicts the assembly deviation of the rotor. Originality/value The Monomer Model realizes the reverse calculation of assembly deformation for the first time, which can be used to identify the weak links that affect the assembly accuracy, thus support the accuracy improvement in the re-assembly stage.
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Liu, Xueshu, Yuxing Yang, Li Huang, Ping Zhang et Hang Gao. « Numerical Analysis of the Influences of Geometrical Deviation on Delamination in Composite Laminates around the Countersunk Hole ». International Journal of Aerospace Engineering 2018 (2018) : 1–11. http://dx.doi.org/10.1155/2018/5061948.
Résumé :
During countersunk hole machining, defects like geometrical deviation of the chamfer angle and delamination are easily introduced into the structure. To investigate the influences of geometrical deviation on delamination propagation around the countersunk hole during assembly, a progressive damage model (PDM) combining cohesive element was proposed and validated. Numerical analyses were then carried out to study delamination propagation behavior under the influences of geometrical parameters including delamination factor, chamfer angle, and location of delamination. The results show that when delamination appears at the transition area of the countersunk hole, the load causing the delamination evolution is much smaller than other cases.
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Kwintarini, Widyanti, Agung Wibowo et Yatna Yuwana Martawirya. « Mathematical Approach for Geometric Error Modeling of Three Axis CNC Vertical Milling Machine ». Applied Mechanics and Materials 842 (juin 2016) : 303–10. http://dx.doi.org/10.4028/www.scientific.net/amm.842.303.
Résumé :
The aim of this paper overviews about to find out the errors that come from three axis CNC vertical milling machine. The errors come from, the CNC milling machine can be modelled into mathematical models and later on these error models will be used to analyse the errors in the measured data. Many errors from CNC machine tools have given significant effects toward the accuracy and repeatability of manufacturing process. There are two error sources come from CNC machine tools such as tool deflection and thermal distortions of machine tool structure. These errors later on will contribute to result in the geometrical deviations of moving axis in CNC vertical milling machine. Geometrical deviations of moving axis such as linear positioning errors, roll, pitch and yaw can be designated as volumetric errors in three axis machine tool. Geometrical deviations of moving axises happen at every axis in three axis CNC vertical milling machine. Geometrical deviations of moving axises in linear and angular movement has the amount of errors up to twenty one errors. Moreover, this geometrical errors play the major role in the total amount of errors and for that particular reason extra attention towards the geometrical deviation errors will be needed along machining process. Each of geometrical error of three axes vertical machining center is modeled using a homogeneous transformation matrix (HTM). The developed mathematical model is used to calculate geometrical errors at each axis and to predict the resultant error vector at the interface of machine tool and workpiece for error compensation.
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Dionisius, Felix, Sugiri ,, Tito Endramawan et Emin Haris. « Geometrical Study of Channel Profile under Incremental Forming Process : Numerical Simulation ». Journal of Mechanical Engineering 16, no 2 (1 août 2019) : 1–10. http://dx.doi.org/10.24191/jmeche.v16i2.15322.
Résumé :
Incremental forming is one of the innovative manufacturing technologies in plate sheet forming techniques. With the incremental forming process, plate formation can be as desired and also easily applied to the manufacturing with a limited number of products. This paper is conducted to find out the smallest geometry of deviation between the design with the results of the process and the best step-down selection using a single point incremental forming (SPIF). The variable variations used in this research was 2-6 (mm) of step-down where this process uses a punch tool in the form of a hemispherical / half ball and with 2 clamps. Numerical simulation method with explicit finite element model was used as a virtual experiment with the helical shaped tool movement. The tool moves to form a blank with a size of 12x160x200 mm into a channel profile with a speed of 8 mm/s. The result showed that the deviation between the product and the design has increased from step down 2-6 mm. The smallest deviations were 3.63 mm for x axis and 12,549 mm of total depth or 4.57% for y axis with 2 mm step down parameter. Whereas for step down 4 mm had the deviation of 3.9 mm and 13.853 of total depth. But for step down 6 mm had failed / damaged.
Thèses sur le sujet "Geometrical deviation model":
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Nguyen, Dinh Son. « The impact of geometrical deviations on product life cycle ». Grenoble INPG, 2010. https://theses.hal.science/tel-00561475.
Résumé :
Aujourd’hui, les exigences des clients concernant le produit qu’ils achètent, exigence telles que la qualité, la fiabilité, la robustesse, l’innovation et le coût sont de plus en plus élevées. Le concepteur du produit doit s’assurer que le produit conçu satisfait aux exigences des clients et des utilisateurs. En d’autres mots, la satisfaction de ceux-ci joue un rôle important dans la conception du produit et du process. Le travail de recherche présenté dans ce mémoire de thèse est une réponse complète pour la gestion des variations géométriques durant le cycle de vie du produit. Le modèle de déviations géométriques du produit exposé dans ce mémoire permet de modéliser les déviations géométriques générées de l’étape de fabrication à l’étape d’assemblage de son cycle de vie. La méthode de simulation Monte-Carlo est utilisée pour générer une image des produits fabriqués. A partir de ces résultats, les déviations géométriques sont intégrées dans la simulation de performance du produit afin d’établir la relation entre la performance et les paramètres des sources de variation. Une image de la performance réelle du produit fabriqué est générée par l’utilisation des résultats de la simulation des déviations géométriques. A partir des résultats de la simulation de performance, les paramètres des sources de variation influençant la performance du produit sont identifiés et classifiés par rapport au leur niveau d’impact. La variance de la variation de la performance est établie par deux approches différentes s’appuyant sur la relation entre la performance et les paramètres. Finalement, la solution de robuste de conception peut être déterminée par minimisation de la variance de la performance du produitToday requirements of customers concerning product they would like to purchase, such as quality, reliability, robustness, innovativeness and cost are more and more tight and high. Thus, product designer must ensure that the designed product meets fully the requirements of customers and users as well. In other words, satisfaction of these plays an important role in the context of design product-process. The research work presented in my thesis is a complete answer for management of geometrical variations throughout the product life cycle. In fact, the geometrical deviation model introduced in my thesis allows to model geometrical deviations generated from the manufacturing to assembly stage of the product life cycle. Monte-Carlo simulation method is then used to generate an image of the real manufactured product. As a result, the geometrical deviations are integrated into simulation of product performance in order to establish the relationship between the performance and the parameters of geometrical deviations or variation sources. An image of the real performance of the manufactured product is generated by using the result of geometrical deviations simulation. From the result of performance simulation, the parameters of variation sources influencing the product performance are identified and classified according to their impact level. The variance of the product performance variation is established by two different approaches based on the relation between the performance and the parameters of geometrical deviations or variation sources. Finally, the robust design solution can be found by minimization of the variance of the product performance variation
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Zhu, Zuowei. « Modèles géométriques avec defauts pour la fabrication additive ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN021/document.
Résumé :
Les différentes étapes et processus de la fabrication additive (FA) induisent des erreurs de sources multiples et complexes qui soulèvent des problèmes majeurs au niveau de la qualité géométrique du produit fabriqué. Par conséquent, une modélisation effective des écarts géométriques est essentielle pour la FA. Le paradigme Skin Model Shapes (SMS) offre un cadre intégral pour la modélisation des écarts géométriques des produits manufacturés et constitue ainsi une solution efficace pour la modélisation des écarts géométriques en FA.Dans cette thèse, compte tenu de la spécificité de fabrication par couche en FA, un nouveau cadre de modélisation à base de SMS est proposé pour caractériser les écarts géométriques en FA en combinant une approche dans le plan et une approche hors plan. La modélisation des écarts dans le plan vise à capturer la variabilité de la forme 2D de chaque couche. Une méthode de transformation des formes est proposée et qui consiste à représenter les effets de variations sous la forme de transformations affines appliquées à la forme nominale. Un modèle paramétrique des écarts est alors établi dans un système de coordonnées polaires, quelle que soit la complexité de la forme. Ce modèle est par la suite enrichi par un apprentissage statistique permettant la collecte simultanée de données des écarts de formes multiples et l'amélioration des performances de la méthode.La modélisation des écarts hors plan est réalisée par la déformation de la couche dans la direction de fabrication. La modélisation des écarts hors plan est effectuée à l'aide d'une méthode orientée données. Sur la base des données des écarts obtenues à partir de simulations par éléments finis, deux méthodes d'analyse modale: la transformée en cosinus discrète (DCT) et l'analyse statistique des formes (SSA) sont exploitées. De plus, les effets des paramètres des pièces et des procédés sur les modes identifiés sont caractérisés par le biais d'un modèle à base de processus Gaussien.Les méthodes présentées sont finalement utilisées pour obtenir des SMSs haute-fidélité pour la fabrication additive en déformant les contours de la couche nominale avec les écarts prédits et en reconstruisant le modèle de surface non idéale complet à partir de ces contours déformés. Une toolbox est développée dans l'environnement MATLAB pour démontrer l'efficacité des méthodes proposéesThe intricate error sources within different stages of the Additive Manufacturing (AM) process have brought about major issues regarding the dimensional and geometrical accuracy of the manufactured product. Therefore, effective modeling of the geometric deviations is critical for AM. The Skin Model Shapes (SMS) paradigm offers a comprehensive framework aiming at addressing the deviation modeling problem at different stages of product lifecycle, and is thus a promising solution for deviation modeling in AM. In this thesis, considering the layer-wise characteristic of AM, a new SMS framework is proposed which characterizes the deviations in AM with in-plane and out-of-plane perspectives. The modeling of in-plane deviation aims at capturing the variability of the 2D shape of each layer. A shape transformation perspective is proposed which maps the variational effects of deviation sources into affine transformations of the nominal shape. With this assumption, a parametric deviation model is established based on the Polar Coordinate System which manages to capture deviation patterns regardless of the shape complexity. This model is further enhanced with a statistical learning capability to simultaneously learn from deviation data of multiple shapes and improve the performance on all shapes.Out-of-plane deviation is defined as the deformation of layer in the build direction. A layer-level investigation of out-of-plane deviation is conducted with a data-driven method. Based on the deviation data collected from a number of Finite Element simulations, two modal analysis methods, Discrete Cosine Transform (DCT) and Statistical Shape Analysis (SSA), are adopted to identify the most significant deviation modes in the layer-wise data. The effect of part and process parameters on the identified modes is further characterized with a Gaussian Process (GP) model. The discussed methods are finally used to obtain high-fidelity SMSs of AM products by deforming the nominal layer contours with predicted deviations and rebuilding the complete non-ideal surface model from the deformed contours. A toolbox is developed in the MATLAB environment to demonstrate the effectiveness of the proposed methods
Chapitres de livres sur le sujet "Geometrical deviation model":
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Paquet, Elodie, Sébastien Le Loch, Benoit Furet, Alain Bernard et Sébastien Garnier. « Numerical Simulation and Experimentation of Additive Manufacturing Processes with Polyurethane Foams ». Dans Lecture Notes in Mechanical Engineering, 48–54. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_9.
Résumé :
AbstractFoam Additive Manufacturing (FAM) is the additive manufacturing process allowing parts to be obtained by depositing layers of polyurethane foam using a high-pressure machine. This inexpensive technology allows large parts to be produced in a reduced time. However, the quality of the parts produced by the FAM technique is greatly affected by the various thermal phenomena present during manufacturing and by the geometrical deviations of the layers due to the expansion of the PU foam. Numerical simulation remains an effective analytical tool for studying these phenomena. The aim of this work is to build a geometric and thermal model predictive of the FAM process by the finite element method, the final objective of which is to provide temperature maps throughout the manufacturing process and also to choose the best 3D printing strategy to have a model with constant cords and the smallest possible form deviation. The proposed model and the various simulation techniques used are detailed in this article. This model is developed under the finite element code Rem3D, and validated by experimental tests carried out on a FAM machinery or a robot, an example of which is detailed in this article.
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Sardina, Jeffrey, Callie Sardina, John D. Kelleher et Declan O’Sullivan. « Analysis of Attention Mechanisms in Box-Embedding Systems ». Dans Communications in Computer and Information Science, 68–80. Cham : Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-26438-2_6.
Résumé :
AbstractLarge-scale Knowledge Graphs (KGs) have recently gained considerable research attention for their ability to model the inter- and intra- relationships of data. However, the huge scale of KGs has necessitated the use of querying methods to facilitate human use. Question Answering (QA) systems have shown much promise in breaking down this human-machine barrier. A recent QA model that achieved state-of-the-art performance, Query2box, modelled queries on a KG using box embeddings with an attention mechanism backend to compute the intersections of boxes for query resolution. In this paper, we introduce a new model, Query2Geom, which replaces the Query2box attention mechanism with a novel, exact geometric calculation. Our findings show that Query2Geom generally matches the performance of Query2box while having many fewer parameters. Our analysis of the two models leads us to formally describe the interaction between knowledge graph data and box embeddings with the concepts of semantic-geometric alignment and mismatch. We create the Attention Deviation Metric as a measure of how well the geometry of box embeddings captures the semantics of a knowledge graph, and apply it to explain the difference in performance between Query2box and Query2Geom. We conclude that Query2box’s attention mechanism operates using “latent intersections” that attend to the semantic properties in embeddings not expressed in box geometry, acting as a limit on model interpretability. Finally, we generalise our results and propose that semantic-geometric mismatch is a more general property of attention mechanisms, and provide future directions on how to formally model the interaction between attention and latent semantics.
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Tofallis, Chris. « Model Fitting for Multiple Variables by Minimising the Geometric Mean Deviation ». Dans Total Least Squares and Errors-in-Variables Modeling, 261–67. Dordrecht : Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-017-3552-0_23.
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Grošelj, Petra, et Gregor Dolinar. « A Geometric Standard Deviation Based Soft Consensus Model in Analytic Hierarchy Process ». Dans Contributions to Management Science, 281–316. Cham : Springer International Publishing, 2012. http://dx.doi.org/10.1007/978-3-030-52406-7_11.
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Rosso, Stefano, Andrea Curtarello, Federico Basana, Luca Grigolato, Roberto Meneghello, Gianmaria Concheri et Gianpaolo Savio. « Modeling Symmetric Minimal Surfaces by Mesh Subdivision ». Dans Lecture Notes in Mechanical Engineering, 249–54. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_40.
Résumé :
AbstractThanks to the great diffusion of additive manufacturing technologies, the interest in lattice structures is growing. Among them, minimal surfaces are characterized by zero mean curvature, allowing enhanced properties such as mechanical response and fluidynamic behavior. Recent works showed a method for geometric modeling triply periodic minimal surfaces (TPMS) based on subdivision surface. In this paper, the deviation between the subdivided TPMS and the implicit defined ones is investigated together with mechanical properties computed by numerical methods. As a result, a model of mechanical properties as a function of the TPMS thickness and relative density is proposed.
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Peterson, Eric, et Bhavleen Kaur. « Printing Compound-Curved Sandwich Structures with Robotic Multi-Bias Additive Manufacturing ». Dans Computational Design and Robotic Fabrication, 526–36. Singapore : Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8405-3_44.
Résumé :
AbstractA research team at Florida International University Robotics and Digital Fabrication Lab has developed a novel method for 3d-printing curved open grid core sandwich structures using a thermoplastic extruder mounted on a robotic arm. This print-on-print additive manufacturing (AM) method relies on the 3d modeling software Rhinoceros and its parametric software plugin Grasshopper with Kuka-Parametric Robotic Control (Kuka-PRC) to convert NURBS surfaces into multi-bias additive manufacturing (MBAM) toolpaths. While several high-profile projects including the University of Stuttgart ICD/ITKE Research Pavilions 2014–15 and 2016–17, ETH-Digital Building Technologies project Levis Ergon Chair 2018, and 3D printed chair using Robotic Hybrid Manufacturing at Institute of Advanced Architecture of Catalonia (IAAC) 2019, have previously demonstrated the feasibility of 3d printing with either MBAM or sandwich structures, this method for printing Compound-Curved Sandwich Structures with Robotic MBAM combines these methods offering the possibility to significantly reduce the weight of spanning or cantilevered surfaces by incorporating the structural logic of open grid-core sandwiches with MBAM toolpath printing. Often built with fiber reinforced plastics (FRP), sandwich structures are a common solution for thin wall construction of compound curved surfaces that require a high strength-to-weight ratio with applications including aerospace, wind energy, marine, automotive, transportation infrastructure, architecture, furniture, and sports equipment manufacturing. Typical practices for producing sandwich structures are labor intensive, involving a multi-stage process including (1) the design and fabrication of a mould, (2) the application of a surface substrate such as FRP, (3) the manual application of a light-weight grid-core material, and (4) application of a second surface substrate to complete the sandwich. There are several shortcomings to this moulded manufacturing method that affect both the formal outcome and the manufacturing process: moulds are often costly and labor intensive to build, formal geometric freedom is limited by the minimum draft angles required for successful removal from the mould, and customization and refinement of product lines can be limited by the need for moulds. While the most common material for this construction method is FRP, our proof-of-concept experiments relied on low-cost thermoplastic using a specially configured pellet extruder. While the method proved feasible for small representative examples there remain significant challenges to the successful deployment of this manufacturing method at larger scales that can only be addressed with additional research. The digital workflow includes the following steps: (1) Create a 3D digital model of the base surface in Rhino, (2) Generate toolpaths for laminar printing in Grasshopper by converting surfaces into lists of oriented points, (3) Generate the structural grid-core using the same process, (4) Orient the robot to align in the direction of the substructure geometric planes, (5) Print the grid core using MBAM toolpaths, (6) Repeat step 1 and 2 for printing the outer surface with appropriate adjustments to the extruder orientation. During the design and printing process, we encountered several challenges including selecting geometry suitable for testing, extruder orientation, calibration of the hot end and extrusion/movement speeds, and deviation between the computer model and the physical object on the build platen. Physical models varied from their digital counterparts by several millimeters due to material deformation in the extrusion and cooling process. Real-time deviation verification studies will likely improve the workflow in future studies.
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López-Correa, Juan Manuel, Caroline König et Alfredo Vellido. « Long Short-Term Memory to Predict 3D Amino Acids Positions in GPCR Molecular Dynamics ». Dans Frontiers in Artificial Intelligence and Applications. IOS Press, 2022. http://dx.doi.org/10.3233/faia220339.
Résumé :
G-Protein Coupled Receptors (GPCRs) are a big family of eukaryotic cell transmembrane proteins, responsible for numerous biological processes. From a practical viewpoint around 34% of the drugs approved by the US Food and Drug Administration target these receptors. They can be analyzed from their simulated molecular dynamics, including the prediction of their behavior in the presence of drugs. In this paper, the capability of Long Short-Term Memory Networks (LSTMs) are evaluated to learn and predict the molecular dynamic trajectories of a receptor. Several models were trained with the 3D position of the amino acids of the receptor considering different transformations on the position of the amino acid, such as their centers of mass, the geometric centers and the position of the α–carbon for each amino acid. The error of the prediction of the position was evaluated by the mean average error (MAE) and root-mean-square deviation (RMSD). The LSTM models show a robust performance, with results comparable to the state-of-the-art in non-dynamic 3D predictions. The best MAE and RMSD values were found for the mass center of the amino acids with 0.078 Å and 0.156 Å respectively. This work shows the potential of LSTM to predict the molecular dynamics of GPRCs.
Actes de conférences sur le sujet "Geometrical deviation model":
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Gao, Chang, Haidong Yu et Bin Gu. « A New Deviation Propagation Model Combining Dimensional Deviation and Welding Deformation of Panel Structures With High Local Stiffness ». Dans ASME 2023 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/imece2023-112739.
Résumé :
Abstract The geometrical accuracy of panel structures jointed by friction stir welding (FSW) is affected by dimensional deviation and assembly deformation, which leads to the assembly deviation difficult to be predicted and traced. The local stiffness of panel structures enhances significantly with the increase of thickness of the structures, and the deformation concentrates in the local assembly area. In this paper, a new deviation propagation model for panel structures considering dimensional deviation and local welding deformation is proposed. The dimensional deviations with multi-tolerance coupling effect are characterized by small displacement torsor (SDT). A virtual feature is constructed for the local welding deformation of panel structure. The deviation propagation model of panel structures is established. The contribution index of each deviation source to the assembly deviation is proposed, and the influence of dimensional deviation and assembly deformation on the geometric accuracy of assembly may be revealed. The FSW experiment is carried out on two plates and the reasonability of the deviation model is verified by comparing with the experimental data. The contribution of dimensional deviation and welding deformation is solved based on the deviation propagation model. The proposed deviation propagation model combining dimensional deviation and welding deformation may be useful for design of structural parameters and assembly process of panel structures.
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Chatterjee, Monish R., et Shih-Tun Chen. « A Geometrical Derivation of WRITE Beam Criteria for Multiplexed Color Hologram Readout Using Wavevector Triads ». Dans Holography. Washington, D.C. : Optica Publishing Group, 1996. http://dx.doi.org/10.1364/holography.1996.htud.3.
Résumé :
The problem of restoring the misaligned output from a grating hologram under READ beam deviations has been investigated recently using a variety of resonant triad models [1-3]. Initially, it was proposed that selective angular and/or wavelength tuning of the READ beam would restore the output beam direction [1]. Subsequently, upon closer examination, it was found that the problem is amenable to different geometrical interpretations depending on whether the grating is untilted or tilted, and whether the READ beam deviation (Δλ or Δθ) is positive or negative [2]. The latter problem has generally been analyzed by assuming a single-deviation model (i.e., with the READ beam having either an angular or a wavelength deviation and not both). It may be shown that the deviation in the desired reconstructed beam direction may be graphically determined from appropriate resonant triads superposed on wavenumber (or β) circles. For the case of an untilted grating with a READ angular mismatch, for instance, an appropriate wavelength tuning will restore the reconstructed beam direction. The amount of tuning necessary will depend on the sign of the angular mismatch (i.e., whether it is greater or less than the Bragg angle). One such scenario is shown in Fig. 1.
3
Schleich, Benjamin, et Sandro Wartzack. « Motion Tolerancing Based on Skin Model Shapes by Form Deviation Parametrization and Meta-Modelling ». Dans ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67227.
Résumé :
The inevitable presence of geometrical part deviations and their effects on the product function and quality forces companies to manage these deviations along the product life-cycle. Computer-aided tolerancing and variation simulation tools support these activities by enabling the early prediction and assessment of the effects of such part deviations. However, available approaches for the tolerance analysis and variation simulation imply shortcomings regarding the consideration of form deviations, particularly when analysing mechanism and moving systems. This paper presents an approach for the motion tolerancing, i. e. for the tolerance analysis of mechanism and moving systems, employing discrete geometry representations of parts with geometrical deviations (Skin Model Shapes). In this regard, a novel method for the parametrization of form deviations is proposed and the use of meta-modelling techniques for the reduction of the computational effort is illustrated. Moreover, the presented approach is applied on two case studies. Based on the obtained results, it can be found, that the consideration of form deviations in the tolerance analysis for mechanism and moving systems may lead to more purposeful tolerancing decisions.
4
Ben Amor, Sabrine, Floriane Zongo, Borhen Louhichi, Antoine Tahan et Vladimir Brailovski. « Dimensional Deviation Prediction Model Based on Scale and Material Concentration Effects for LPBF Process ». Dans 2022 International Additive Manufacturing Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/iam2022-93969.
Résumé :
Abstract Additive Manufacturing (AM) processes generate parts layer-by-layer without using formative tools. The resulting advantages highlight the capability of AM to become an inherent part of product development. However, process-specific challenges such as high surface roughness, the stair-stepping effect, or dimensional deviations inhibit the establishment of AM at the industrial scale. Thus, AM parts often need to be post-processed using established manufacturing processes. Many process parameters and geometrical factors influence the dimensional accuracy in AM. Published results relating to these deviations are also difficult to compare because they are based on several geometries that are manufactured using different processes, materials, and machine settings. Laser Powder Bed Fusion (LPBF) is gaining in popularity, but one of the obstacles facing its larger industrial use is the limited knowledge of its dimensional and geometrical performances. Therefore, using it requires studying the process and improving the accuracy of the parts involved. This paper represents a new attempt to predict dimensional deviations of LPBF parts. During the project, the scale- and material concentration-related phenomena were implemented in a new image analysis model and applied to the as-built part. We carried out a comparison between the results of the proposed model with those obtained from numerical analyses and experiments. The model does not use finite element analysis, takes less time to compute, and provides reasonable prediction accuracy.
5
Lindstro¨m, David E. « Robustness Analysis of Airfoil Performance ». Dans ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28261.
Résumé :
We demonstrate a technique to evaluate the aerodynamic robustness of a given blade profile which it is exposed to stochastic geometrical variation. The technique is based on random fields, with geometrical deviations continuously defined over the entire structure, with a prescribed statistical distribution function and a given correlation between these deviations. Control points are defined on the blade surface to model the blade geometry disturbances. At each control point a stochastic deviation is defined, which acts in the normal direction of the blade. By modeling disturbances in the normal direction instead of in the separate Cartesian directions, we automatically reduce the number of stochastic variables by a factor two. The perturbation variables are transformed via Karhunen-Loe`ve eigenvalue decomposition, giving stochastically independent variables. The robustness is finally estimated by a Monte Carlo simulation, where computational fluid dynamic simulations are performed to evaluate the resulting change in blade performance for given geometrical perturbations.
6
Weihard, Stefan, Andreas Hupfer et Hans-Peter Kau. « Statistical Impact of Manufacturing Tolerances on Axial Gaps Between Vane Segments and the Rotor of Axial Flow Turbo-Compressors ». Dans ASME Turbo Expo 2013 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95532.
Résumé :
Geometrical deviations arising from the manufacturing process significantly influence the axial gaps between rotating and nonrotating parts. To optimize axial gaps and thus reduce the overall length and weight of the compressor, it is essential to take the statistical nature of these deviations into account. The focus of this paper is to identify complex three-dimensional effects caused by geometrical uncertainties. The results can be then used to define an appropriate level of detail for the simulation model in order to accurately predict the probability distribution of axial gaps. In the simulation model the parts are assembled according to defined mechanical constraints and the paper presents mathematical models regarding this. A simplified 2D model of a sectional view and a detailed 3D model are implemented and investigated. A 2D tolerance analysis shows that a statistical gap tolerance can be defined based on geometrical parameters. It must be assumed that a certain percentage of all gap values will fall below the lower specification limit for this tolerance interval. A detailed 3D analysis, however, results in a change in the probability distribution of the gap values compared to the simplified 2D analysis. In addition to the standard deviation, the mean value of the gap is reduced significantly. Therefore, a simplified 2D approach may yield invalid results. What this effect is will depend on the configuration. One influencing factor is the number of vane segments in the compressor stage. A sensitivity analysis is presented which identifies and quantifies the impact of such important design parameters.
7
Tachikawa, Tomokazu, Nobuaki Kurita, Morimasa Nakamura, Daisuke Iba et Ichiro Moriwaki. « Calculation Model for Internal Gear Skiving With a Pinion-Type Cutter Having Pitch Deviation and a Run-Out ». Dans ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46402.
Résumé :
As the emerging economies expand, demand for low cost production of internal gears has been increasing. And skiving is in focus as a potential method than can meet this demand. Skiving was invented in 1910, since then, mechanical machine has been developed to NC machine and cutter design technologies have developed dramatically. As a result, several machine and tool manufacturer started to release their skiving machine and skiving cutter as well. Furthermore, many studies on the kinematics have been conducted both in research institutions and private companies. However, most of these studies are subject to understanding the cutting mechanisms as a basic research and establishing cutter design methods. For further improvement and boost widespread application of the process, optimization of the manufacturing process is an issue. Particularly, the effects of cutter accuracy and cutter set up deviations on the skived gear are important to ensure reliability of the process. Unfortunately, few studies on those effects can be found. In this paper, geometrical model that can predict the effect of pitch deviation and of run out of a cutter on a skived gear is proposed. Experiments were also carried out to verify the validity of the model, and the results were in good agreement with the simulated ones.
8
Dong, Yiwei, Qi Zhao, Xiaolin Li, Xiaoji Li et Jun Yang. « Methodology to Develop Geometric Modeling of Accurate Drilled Cooling Holes on Turbine Blades ». Dans ASME Turbo Expo 2017 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63024.
Résumé :
Film cooling is one of most developed technologies which enhance the gas turbine blades operation in today’s high-thrust-to-weight-ratio gas engines. The determination of the accurate cooling holes of turbine blades is of vital importance to improving the cooling performance. However, in all current methods for manufacturing drilled cooling holes on turbine blades, the complexity of the production processes will ineluctably cause unexpected consequences such as the deformation of the turbomachinery parts, the locating error caused by fixture layouts. These issues will cause deviations in the geometry and position of the drilled holes. In this paper, a methodology is proposed to analyze the deviation and to establish an improved geometric model of drilled cooling holes with accurate positional and geometrical parameters on turbine blades. The discontinuous deformation, including the non-uniform wall thickness and shrinkage distribution, was established by deformation characteristics decoupling analysis; the surface error generated by locating error was obtained using locating error analysis. An accurate model for film cooling holes can be established by considering the process-induced deviations in geometry and positioning. The relevance of the proposed method is verified using numerical and experimental results.
9
Chen, Pengyuan, Shun Liu, Sun Jin et Qunfei Gu. « Geometric Modeling and Characterization of Wall Thickness for Complex Cylindrical Thin-Walled Parts With Uncertain Manufacturing Deviations ». Dans ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73185.
Résumé :
Abstract The complex cylindrical thin-walled parts have been widely used in manufacturing field with high precision requirement of wall thickness. However, due to the existence of initial uncertain manufacturing deviations, such as blank casting errors, initial shape deviations and clamping deformations, there will be a large geometric deviation between real blank workpiece and theoretical design model. In order to solve the problem in lacking of reliable geometrical model for trajectory planning in face milling of complex cylindrical thin-walled parts, this paper proposes a method for accurate modeling and characterization of wall thickness considering the uncertain geometric deviations based on point cloud reconstruction. First, based on feature extraction and meshing process of point clouds measured with high-definition metrology both for inner and outer surfaces, subregions of each point cloud are adaptively fitted into small curved surfaces. And then NURBS surfaces are applied to connect adjacent subregions in order to form a high-precision solid model of entire workpiece. Furthermore, a characterization method of real wall thickness in milling areas is proposed. Based on the sampling mesh nodes of inner surface being the interesting points for milling areas, wall thicknesses are characterizing as distances between those sampling nodes and the outer meshed surface with an improved KD-Tree algorithm. Based on the proposed method, a meshed CAD model of real workpiece can be constructed with an error range within 0.2mm; and the wall thicknesses of milling areas can be characterized by the extracted sampling nodes. It provided an efficient methodology for geometric modeling and characterization of wall thickness of complex cylindrical thin-walled parts, which is useful for milling trajectory planning.
10
Colosimo, B. M. « Robust in-line qualification of lattice structures manufactured via laser powder bed fusion ». Dans Italian Manufacturing Association Conference. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902714-28.
Résumé :
Abstract. The shape complexity enabled by AM would impose new part inspection systems (e.g., x-ray computed tomography), which translate into qualification time and costs that may be not affordable. However, the layerwise nature of the process potentially allows anticipating qualification tasks in-line and in-process, leading to a quick detection of defects since their onset stage. This opportunity is particularly attractive in the presence of lattice structures, whose industrial adoption has considerably increased thanks to AM. This paper presents a novel methodology to model the quality of lattice structures at unit cell level while the part is being built, using high resolutions images of the powder bed for in-line geometry reconstruction and identification of deviations from the nominal shape. The methodology is designed to translate complex 3D shapes into 1D deviation profiles that capture the “geometrical signature” of the cell together with the reconstruction uncertainty.
Rapports d'organisations sur le sujet "Geometrical deviation model":
1
Abrahamson, Norman, et Zeynep Gülerce. Regionalized Ground-Motion Models for Subduction Earthquakes Based on the NGA-SUB Database. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, décembre 2020. http://dx.doi.org/10.55461/ssxe9861.
Résumé :
A set of global and region-specific ground-motion models (GMMs) for subduction zone earthquakes is developed based on the database compiled by the Pacific Earthquake Engineering Research Center (PEER) Next Generation Attenuation - Subduction (NGA-SUB) project. The subset of the NGA-SUB database used to develop the GMMs includes 3914 recordings from 113 subduction interface earthquakes with magnitudes varying between 5 and 9.2 and 4850 recordings from 89 intraslab events with magnitudes varying between 5 and 7.8. Recordings in the back-arc region are excluded, except for the Cascadia region. The functional form of the model accommodates the differences in the magnitude, distance, and depth scaling for interface and intraslab earthquakes. The magnitude scaling and geometrical spreading terms of the global model are used for all regions, with the exception of the Taiwan region which has a region-specific geometrical spreading scaling. Region-specific terms are included for the large distance (linear R) scaling, VS30 scaling, Z2.5 scaling, and the constant term. The nonlinear site amplification factors used in Abrahamson et al. (2016) subduction GMM are adopted. The between-event standard deviation piece of the aleatory variability model is region and distance independent; whereas, the within-event standard deviations are both region and distance dependent. Region-specific GMMs are developed for seven regions: Alaska, Cascadia, Central America, Japan, New Zealand, South America, and Taiwan. These region-specific GMMs are judged to be applicable to sites in the fore-arc region at distances up to 500 km, magnitudes of 5.0 to 9.5, and periods from 0 to 10 sec. For the Cascadia region, the region-specific model is applicable to distances of 800 km including the back-arc region. For the sites that are not in one of the seven regions, the global GMM combined with the epistemic uncertainty computed from the range of the regional GMMs should be used.
2
Foeken, van, et Gresnigt. L51809 Buckling and Collapse of UOE Manufactured Steel Pipes. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), novembre 1998. http://dx.doi.org/10.55274/r0010236.
Résumé :
In the past 20 years, much research has been conducted into buckling and collapse of pipelines under external pressure, bending or tension and combinations. Also many finite element analyses have been performed into the behavior of pipelines under these loads. The available test results show considerable scatter, which is considered to be caused by variations in the stress-strain relationship, the anisotropy of the steel, the Bauschinger effect, the geometrical deviations, the residual stresses, the test conditions, etc. The manufacturing method (seamless, UO, UOE) has a considerable influence on these properties and on the collapse and local buckling resistance. In this project, design formulations for collapse and buckling with appropriate safety factors, calibrated against experimental and numerical models using probabilistic methods, have been selected for a practical range of design considerations. The project consisted of three parts: experiments, probabilistic calculations, and finite element calculations.