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.

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.

A Dynamic Analysis Of The Impact Of Air Pollution On The daylight Availability In An Open-plan Office In London

2021 ◽  
pp. 94-103
Author(s):  
Jiangtao Du ◽  
Steve Sharples
Keyword(s):  
Air Pollution ◽  
Urban Areas ◽  
Simulation Analysis ◽  
Design Stage ◽  
Design Strategies ◽  
Early Design Stage ◽  
Pollutant Deposition ◽  
Open Plan ◽  
Building Project ◽  
The Impact

The deposition of air pollutants on glazing can significantly affect the daylight transmittance of building fenestration systems in urban areas. This study presents a simulation analysis of the impact of air pollution and glazing visual transmittance on indoor daylight availability in an open-plan office in London. First, the direct links between glazing visual transmittance and daylighting conditions were developed and assessed. Second, several simple algorithms were established to estimate the loss of daylight availability due to the pollutant deposition at the external surface of vertical glazing. Finally, some conclusions and design strategies to support facade planning at the early design stage of an urban building project were developed.

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.

Approximation of the added resistance of ships with small draft or in ballast condition by empirical formula

2017 ◽  
Vol 233 (1) ◽  
pp. 27-40 ◽  
Author(s):  
Shukui Liu ◽  
Apostolos Papanikolaou
Keyword(s):  
Parametric Study ◽  
Empirical Formula ◽  
Power Estimation ◽  
Design Stage ◽  
Added Resistance ◽  
Regular Waves ◽  
Early Design Stage ◽  
Cruise Ships ◽  
New Formula ◽  
The Impact

An attempt was made to extend and further tune the existing formula for approximating the added resistance in head seas to cover a wider range of speed and to account the impact of loading conditions; a new parameter based on B/ T was introduced after conducting extensive parametric study to capture the influence of draft on the added resistance; the trim effect has also been investigated; Furthermore, the draft effect on the added resistance due to diffraction is further tuned and simplified. The derived formula uses only a few input, including only some ship dimensions to yield an estimation of the added resistance of ships in regular waves. Numerical results show that the added resistance of various ships in head seas at low speeds, as well as the added resistance of tankers in ballast condition and cruise ships, can be properly captured by the new formula. Hence, it meets the demand of fast examination of the minimum power; it can also be used in the early design stage of a ship for power estimation.

Handling and Primary Ride Comfort Development in Early Design Stage by Means of 1D Modeling Approach and Multi Attribute Optimization Process

2011 ◽  
Author(s):  
Stefano Alneri ◽  
Paolo di Carlo ◽  
Alessandro Toso ◽  
Stijn Donders
Keyword(s):  
Performance Metrics ◽  
Ride Comfort ◽  
Experimental Tests ◽  
Complex Model ◽  
Design Stage ◽  
Time Saving ◽  
Vehicle Performance ◽  
Early Design Stage ◽  
Automotive Market ◽  
The Impact

Today the automotive market is ever more competitive and vehicles must satisfy the requirements of the customers in all respects: handling, comfort, acoustics, fuel economy, etc. Therefore OEMs have to launch innovative products in a short development timeline: the time to market (TTM) of new vehicles has continually decreased and nowadays the developing process of a new car is completed in less years than in the past. This scenario emphasizes the role of CAE in the vehicle design engineering design and the necessity of exploiting its potentialities, in order to shorten the TTM and to reduce the impact of experimental tests on it. In this context a step-by-step approach with multi-physics 1D environment such as LMS Imagine. Lab AMESim is proposed in order to monitor vehicle performances in all the design stages, thanks to the employment of models with increasing complexity. In addition the ultimate step can be employed for performing a multi attribute optimization on vehicle performance metrics in order to find the best attributes balancing and to pass the preliminary recommendations to the design with a considerable time-saving respect to 3D MBS models. This paper briefly describes the process for building 1D models with LMS Imagine.Lab AMESim and moreover it shows the definition of a multi attribute optimization algorithm in terms of handling performances with the most complex model.

scholarly journals The impact of vehicle silhouettes on perceptions of car environmental friendliness and safety in 2009 and 2016: a comparative study

2017 ◽  
Vol 3 ◽  
Author(s):  
Youyi Bi ◽  
Sixuan Li ◽  
David Wagner ◽  
Tahira Reid
Keyword(s):  
Comparative Study ◽  
Inverse Relationship ◽  
Environmentally Friendly ◽  
Design Stage ◽  
Environmental Friendliness ◽  
Early Design ◽  
Early Design Stage ◽  
Within Subjects ◽  
Perceptions Of Safety ◽  
The Impact

Automakers are interested in creating optimal car shapes that can visually convey environmental friendliness and safety to customers. This research examined the influence of vehicle form on perceptions based on two subjective inference measures: safety and perceived environmental friendliness (PEF). A within-subjects study was conducted in 2009 (Study 1) to study how people would evaluate 20 different vehicle silhouettes created by designers in industry. Participants were asked to evaluate forms on several scales, including PEF, safety, inspired by nature, familiarity, and overall preference. The same study was repeated in 2016 (Study 2). The results from the first study showed an inverse relationship between PEF and perceptions of safety. That is, vehicles that appeared to be safe were perceived to be less environmentally friendly, and vice versa. Participants in the second study showed a similar trend, but not as strongly as the 2009 participants. Several shape variables were identified to be correlated with participants’ PEF and safety ratings. The changes in the trend of participants’ evaluations over seven years were also discussed. These results can provide designers with insights into how to create car shapes with balanced PEF and safety in the early design stage.

Comparison of Two Similar Mathematical Models for Tolerance Analysis: T-Map and Deviation Domain

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Mathieu Mansuy ◽  
Max Giordano ◽  
Joseph K. Davidson
Keyword(s):  
Computer Aided Design ◽  
Graphical Representation ◽  
Tolerance Analysis ◽  
Design Stage ◽  
Mathematical Tool ◽  
Resolution Method ◽  
Parallel Links ◽  
Similarities And Differences ◽  
Aided Design ◽  
The Impact

The major part of production cost of a manufacturing product is set during the design stage and especially by the tolerancing choice. Therefore, a lot of work involves trying to simulate the impact of these choices and provide an automatic optimization. For integrating this modeling in computer aided design (cad) software, the tolerancing must be modeled by a mathematical tool. Numerous models have been developed but few of them are really efficient. Two advanced models are “T-map” model developed by Joseph K. Davidson and “deviation domain” developed by Max Giordano. Despite the graphical representation of these two models seems to be similar, they have significant differences in their construction and their resolution method. These similarities and differences highlight the needs of tolerancing modeling tool in each kind of problems, especially in case of assembly with parallel links.

scholarly journals Healthy Gaming – Video Game Design to promote Health

2011 ◽  
Vol 02 (02) ◽  
pp. 128-142 ◽  
Author(s):  
L. Fernandez-Luque ◽  
T. Tøllefsen ◽  
E. Brox
Keyword(s):  
Video Game ◽  
Game Design ◽  
Educational Games ◽  
Design Principles ◽  
Design Stage ◽  
Design Elements ◽  
Early Design Stage ◽  
Persuasive Games ◽  
Games For Health ◽  
The Impact

Summary Background: There is an increasing interest in health games including simulation tools, games for specific conditions, persuasive games to promote a healthy life style or exergames where physical exercise is used to control the game. Objective: The objective of the article is to review current literature about available health games and the impact related to game design principles as well as some educational theory aspects. Methods: Literature from the big databases and known sites with games for health has been searched to find articles about games for health purposes. The focus has been on educational games, persuasive games and exergames as well as articles describing game design principles. Results: The medical objectives can either be a part of the game theme (intrinsic) or be totally dispatched (extrinsic), and particularly persuasive games seem to use extrinsic game design. Peer support is important, but there is only limited research on multiplayer health games. Evaluation of health games can be both medical and technical, and the focus will depend on the game purpose. Conclusion: There is still not enough evidence to conclude which design principles work for what purposes since most of the literature in health serious games does not specify design methodologies, but it seems that extrinsic methods work in persuasion. However, when designing health care games it is important to define both the target group and main objective, and then design a game accordingly using sound game design principles, but also utilizing design elements to enhance learning and persuasion. A collaboration with health professionals from an early design stage is necessary both to ensure that the content is valid and to have the game validated from a clinical viewpoint. Patients need to be involved, especially to improve usability. More research should be done on social aspects in health games, both related to learning and persuasion.

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.

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