On the Selection of Sensitivity Analysis Methods in the Context of Tolerance Management

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Björn Heling ◽  
Thomas Oberleiter ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Fuzzy Arithmetic ◽  
Early Design Stage ◽  
Advantages And Disadvantages ◽  
Technical Requirements ◽  
Geometric Deviations ◽  
Weak Points ◽  
Wear Products ◽  
Selection Of

Although mass production parts look the same at first sight, every manufactured part is unique, at least on a closer inspection. The reason for this is that every manufactured part is inevitable subjected to different scattering influencing factors and variation in the manufacturing process, such as varying temperatures or tool wear. Products, which are built from these deviation-afflicted parts, consequently show deviations from their ideal properties. To ensure that every single product nevertheless meets its technical requirements, it is necessary to specify the permitted deviations. Furthermore, it is crucial to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process, the imperfect parts are assembled virtually and the effects of the geometric deviations can be calculated. Since the tolerance analysis enables engineers to identify weak points in an early design stage, it is important to know which contribution every single tolerance has on a certain quality-relevant characteristic to restrict or increase the correct tolerances. In this paper, four different methods to calculate the sensitivity are introduced and compared. Based on the comparison, guidelines are derived which are intended to facilitate a selection of these different methods. In particular, a newly developed approach, which is based on fuzzy arithmetic, is compared to the established high–low–median method, a variance-based method, and a density-based approach. Since all these methods are based on different assumptions, their advantages and disadvantages are critically discussed based on two case studies.

Fuzzy Sensitivity Analysis in the Context of Dimensional Management

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Thomas Oberleiter ◽  
Björn Heling ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Special Focus ◽  
Total System ◽  
Early Design Stage ◽  
Technical Requirements ◽  
Geometric Deviations ◽  
Weak Points ◽  
Dimensional Management ◽  
The Impact

Real components always deviate from their ideal dimensions. This makes every component, even a serial production, unique. Although they look the same, differences can always be observed due to different scattering factors and variations in the manufacturing process. All these factors inevitably lead to parts that deviate from their ideal shape and, therefore, have different properties than the ideal component. Changing properties can lead to major problems or even failure during operation. It is necessary to specify the permitted deviations to ensure that every single product nevertheless meets its technical requirements. Furthermore, it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process, components are assembled virtually and varied with the uncertainties specified by the tolerances. A variation simulation is one opportunity to calculate these effects for geometric deviations. Since tolerance analysis enables engineers to identify weak points in an early design stage, it is important to know the contribution that every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper, a fuzzy-based method to calculate the sensitivity is introduced and compared with the commonly used extended Fourier amplitude sensitivity test (EFAST) method. Special focus of this work is the differentiation of the sensitivity for the total system and the sensitivities for the subsystems defined by the α-cuts of the fuzzy numbers. It discusses the impact of the number of evaluations and nonlinearity on sensitivity for EFAST and the fuzzy-based method.

Comparison of Different Sensitivity Analysis Methods in the Context of Dimensional Management

2017 ◽  
Author(s):  
Björn Heling ◽  
Thomas Oberleiter ◽  
Benjamin Schleich ◽  
Kai Willner ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Sensitivity Analyses ◽  
Design Stage ◽  
Fuzzy Arithmetic ◽  
Early Design Stage ◽  
Technical Requirements ◽  
Strongly Connected ◽  
Geometric Deviations ◽  
Comparison Of The Results ◽  
Dimensional Management

Although mass production parts look the same, every manufactured part is unique, at least on a closer inspection. The reason for this is that every manufactured part is inevitable subjected to different scattering influencing factors and variation in the manufacturing process, such as varying temperatures or tool wear. All these factors inevitably lead to parts, which deviate from their ideal shape. Products, which are built from these deviation-afflicted parts consequently show deviations from their ideal properties. To ensure that every single product nevertheless meets its technical requirements, it is necessary to specify the permitted deviations. Furthermore it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process the imperfect parts are assembled virtually and the effects of the geometric deviations can be calculated during a variation simulation. Since the tolerance analysis is to enable engineers to identify weak points in an early design stage it is important to know which contribution every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper two different approaches are shown and compared to represent the statistical behavior and the strongly connected sensitivity analyses. In particular a newly developed approach, which is based on fuzzy arithmetic, is compared to the established EFAST-method. The exemplary application of both methods and the comparison of the results are illustrated on a case study.

CAD-Based Tolerance Analysis in Preliminary Design Stages Enabling Early Tolerance Evaluation

2018 ◽  
Author(s):  
Stefan Goetz ◽  
Benjamin Schleich ◽  
Sandro Wartzack
Keyword(s):  
Tolerance Analysis ◽  
Design Stage ◽  
Preliminary Design ◽  
Design Changes ◽  
Preliminary Design Stage ◽  
Geometric Deviations ◽  
Set Up ◽  
Quality Of Products ◽  
Analysis Models

Associated with manufacturing and assembly processes, inevitable geometric deviations have a decisive influence on the function and quality of products. Therefore, their consideration and management are important tasks in product development. Moreover, to meet the demand for short development times, the front-loading of design processes is indispensable. This requires early tolerance analyses evaluating the effect of deviations in a design stage, where the product’s geometry has not yet been finally defined. Since such an early tolerance consideration allows quick and economic design changes seeking for robust designs, it is advisable that the design engineer, who is entirely familiar with the design, should take this step. For this purpose, this paper presents an easy-to-use CAD-based tolerance analysis method for skeleton models. The relevant part deviations are represented by varying geometric dimensions with externally driven family tables. The approach comprises the strength of vector-based methods but does not require an expensive set-up of tolerance analysis models. Particularly, the novelty of this method lies in the CAD-internal sampling-based tolerance analysis of simple geometries without the use of expensive CAT software. This enables designers to evaluate the effect of tolerances already at the preliminary design stage. Using a case study, the presented approach is compared with the conventional vector-based tolerance analysis.

scholarly journals Dimensional Variations of General Curved Composite Parts

2008 ◽  
Vol 41-42 ◽  
pp. 377-383
Author(s):  
Chen Song Dong
Keyword(s):  
Composite Materials ◽  
Process Development ◽  
Closed Form Solution ◽  
Weight Ratio ◽  
Tolerance Analysis ◽  
High Strength ◽  
Form Solution ◽  
Design Stage ◽  
Early Design Stage ◽  
Manufacturing Assembly

With the increasing demands of energy efficiency and environment protection, composite materials have become an important alternative for traditional materials. Composite materials offer many advantages over traditional materials including: low density, high strength, high stiffness to weight ratio, excellent durability, and design flexibility. Despite all these advantages, composite materials have not been as widely used as expected because of the complexity and cost of the manufacturing process. One of the main causes is associated with poor dimensional control. General curved composite parts are often used as the structural components in the composite industry. Due to the anisotropic material nature, process-induced dimensional variations make it difficult for tighttolerance control and limit the use of composites. This research aims to develop a practical approach for the design of general curved composite parts and assembly. First, the closed-form solution for the process-induced dimensional variations, which is commonly called spring-in, was derived. For a general curved composite part, a Structural Tree Method (STM) was developed to divide the curve into a number of pieces and calculate the dimensional variations sequentially. This method can be also applied to an assembly of composite parts. The approach was validated through a case study. The method presented in this paper provides a convenient and practical tool for the dimensional and tolerance analysis in the early design stage of general curved composite parts and assembly, which is extremely useful for the realization of affordable tight tolerance composites. It also provides the foundation of Integrated Product/Process Development (IPPD) and Design for Manufacturing/Assembly (DFM/DFA) for composites.

Module Division Planning Considering Uncertainties

2009 ◽  
Vol 25 (03) ◽  
pp. 153-160 ◽  
Author(s):  
Kumar Ajay Asok ◽  
Kazuhiro Aoyama
Keyword(s):  
Fuzzy Logic ◽  
Graph Theory ◽  
Planning Process ◽  
Design Stage ◽  
Ship Structure ◽  
Factors Affecting ◽  
Early Design ◽  
Early Design Stage ◽  
Early Design Stages ◽  
Selection Of

During the module division planning process, various factors such as shipyard facilities, ship structure, outfitting, material availability, and so forth must be considered simultaneously. At the early design stage, detailed information on these factors or constraints might not be certain. This uncertainty makes the generation of optimum module division plan difficult. In this paper, a system is proposed for module division planning considering the uncertainties in the information at the early design stages. Module division planning is defined as the process of selection of the best module division seam locations. Module division plans are evaluated and ranked based on the locations of seams in each pattern and also the properties of modules in each the pattern. Various factors affecting module division planning and their uncertainties are also considered. Based on the evaluation, some of the "preferable" module division plans can be selected. The system is developed based on graph theory and fuzzy logic.

Early design stage selection of best manufacturing process

2019 ◽  
Vol 31 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Douglas C. Eddy ◽  
Sundar Krishnamurty ◽  
Ian R. Grosse ◽  
Mark Steudel
Keyword(s):  
Manufacturing Process ◽  
Design Stage ◽  
Early Design ◽  
Early Design Stage ◽  
Selection Of

Produktionsangepasste Konstruktion*/Production-adjusted design for hot die forging processes

2016 ◽  
Vol 106 (03) ◽  
pp. 175-180
Author(s):  
B.-A. Prof. Behrens ◽  
M. Dannenberg ◽  
S. Mohammadifard ◽  
J.-D. Offers ◽  
A. Santangelo
Keyword(s):  
Design Stage ◽  
Specific Information ◽  
Early Design ◽  
Software Application ◽  
Early Design Stage ◽  
Die Forging ◽  
Hot Die Forging ◽  
Selection Of ◽  
Production Resources

Der Fachaufsatz stellt eine Methode vor, mit der bereits während der Konstruktion von Schmiedewerkzeugen produktionsspezifische Informationen berücksichtigt werden. Für die produktionsgerechte Konstruktion wird unter Berücksichtigung von Fertigungsmitteldaten und daraus abgeleiteten Kennzahlen eine Zusatzanwendung innerhalb einer CAD-Umgebung entwickelt. Diese gestattet bereits in der frühen Konstruktionsphase eine geführte Fertigungsmittelauswahl und automatisierte Werkzeuganpassung.   A methodology is presented providing production-specific information for the design of hot die forging tools. For a production-adjusted design an additional prototypical software application within a conventional CAD-framework is developed including the properties of the production resources and derived indicators. The application allows already in the early design stage a guided selection of production resources and an automatic geometric adaption of the forging tools.

Reingold, N. (2017). Literature of English Modernism. History. Problematics. Poetics. A textbook. Moscow: RGGU.

2020 ◽  
Vol 1 (1) ◽  
pp. 276-281
Author(s):  
O. Yu. Panova
Keyword(s):  
Detailed Analysis ◽  
Critical Appraisal ◽  
Academic Discourse ◽  
Literary Modernism ◽  
Reading List ◽  
Weak Points ◽  
University Curricula ◽  
Points Of View ◽  
Selection Of

The review gives a write-up of the edition, its structure, composition and its material. The guidelines for teaching British literary Modernism, methods and concepts offered in the book are subject to a detailed analysis. The critical appraisal of its innovations, its tendency to extend and revise the canonical topics and the reading list, offer new points of view and unordinary approaches (in contrast with typical university curricula) is followed by critical remarks targeted at its weak points – poor reasoning and certain groundless pronouncements one sometimes comes across, principles that underlie the selection of material in particular chapters and paragraphs, correctness of style and conformity with the conventions of academic discourse. It is also emphasized that the book in question is a fascinating and enriching reading that will be duly appreciated by the students as well as colleagues and all readers interested in the British literary Modernism.

scholarly journals TRACING THE EMERGENCE OF DESIGN PROBLEMS AND THEIR IMPACTS ON THE COMPLEXITY OF ENGINEERING SOLUTIONS

2021 ◽  
Vol 1 ◽  
pp. 3229-3238
Author(s):  
Torben Beernaert ◽  
Pascal Etman ◽  
Maarten De Bock ◽  
Ivo Classen ◽  
Marco De Baar
Keyword(s):  
Large Scale ◽  
Fusion Reactor ◽  
Design Stage ◽  
Engineering Model ◽  
Design Problems ◽  
Nuclear Fusion Reactor ◽  
Early Design Stage ◽  
Iterative Design ◽  
Problems And Solutions ◽  
Emergent Design

AbstractThe design of ITER, a large-scale nuclear fusion reactor, is intertwined with profound research and development efforts. Tough problems call for novel solutions, but the low maturity of those solutions can lead to unexpected problems. If designers keep solving such emergent problems in iterative design cycles, the complexity of the resulting design is bound to increase. Instead, we want to show designers the sources of emergent design problems, so they may be dealt with more effectively. We propose to model the interplay between multiple problems and solutions in a problem network. Each problem and solution is then connected to a dynamically changing engineering model, a graph of physical components. By analysing the problem network and the engineering model, we can (1) derive which problem has emerged from which solution and (2) compute the contribution of each design effort to the complexity of the evolving engineering model. The method is demonstrated for a sequence of problems and solutions that characterized the early design stage of an optical subsystem of ITER.

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