Tolerance Synthesis Modeling Based on Degree of Freedom of Geometric Variations of Features

2011 ◽  
Vol 201-203 ◽  
pp. 151-156
Author(s):  
Ben Sheng Xu ◽  
Can Wang ◽  
Mei Fa Huang
Keyword(s):  
Three Dimensional ◽  
Tolerance Analysis ◽  
Matrix Inversion ◽  
Degree Of Freedom ◽  
Coordinate Systems ◽  
Tolerance Zone ◽  
Tolerance Synthesis ◽  
3D Space ◽  
The Relationship

A tolerance synthesis model is established based on degree of freedom of geometric variations of features in this paper. The method allows a designer to analyze the relationship between geometric variations of features of a part and functional requirement of assembly (FRA). Firstly, tolerance is modeled with DOFs of geometric variations of features and the tolerance zone is expressed with six kinematic DOFs in three-dimensional (3D) space. Secondly, the stack-up of geometric variations of features is formulated as explicit tolerance analysis equations using kinematical coordinate systems associated with each feature. To express mathematically the relationship between given FRA values and the corresponding DOFs of geometric variations of features, the reverse synthesis equations are obtained using a matrix inversion scheme of the tolerance analysis equations. Finally, a case study is used to illustrate the proposed method.

The magnetotelluric impedance tensor properties with respect to rotations

Geophysics ◽  
1985 ◽  
Vol 50 (10) ◽  
pp. 1610-1617 ◽  
Author(s):  
Simon Spitz
Keyword(s):  
Data Analysis ◽  
Coordinate System ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Impedance Tensor ◽  
Coordinate Systems ◽  
Magnetotelluric Data ◽  
Conventional Analysis ◽  
Complete Set ◽  
The Relationship

A serious limitation to conventional data analysis is that the data refer mainly to elongated bodies. When three‐dimensional distortions are present, quantitative interpretation based only on the off‐diagonal elements of the conventionally rotated impedance tensor is inadequate, because these off‐diagonal elements are insensitive to the tensor trace. The impedance tensor eigenstate formulation proposed in the literature defines a complete set of parameters suitable for recognition of three‐dimensionality. Generally, though, the eigenvalues do not stand for the off‐diagonal elements of an impedance tensor measured in a physical coordinate system. It is shown how the eigenvalues are modified when the relationship between coordinate system rotations and the eigenstate formulation is clarified. A generalization of the conventional analysis results, but the rotation angle obtained is neither unique nor complete To improve the situation, two new analytical rotation angles are proposed. These angles define two complete intrinsic coordinate systems suitable for magnetotelluric data analysis when a general three‐dimensional structure is involved.

Application of a Unified Jacobian—Torsor Model for Tolerance Analysis

2003 ◽  
Vol 3 (1) ◽  
pp. 2-14 ◽  
Author(s):  
Alain Desrochers ◽  
Walid Ghie ◽  
Luc Laperrie`re
Keyword(s):  
Three Dimensional ◽  
Tolerance Analysis ◽  
Small Displacement ◽  
Manufacturing Processes ◽  
Functional Requirements ◽  
Tolerance Zone ◽  
Kinematic Chains ◽  
Final Assembly ◽  
Novel Method ◽  
Assembly Constraints

Because of uncertainties in manufacturing processes, a mechanical part always shows variations in its geometrical characteristics (ex. form, dimension, orientation and position). Quality then often reflect how well tolerances and hence, functional requirements, are being achieved by the manufacturing processes in the final product. From a design perspective, efficient methods must be made available to compute, from the tolerances on individual parts, the value of the functional requirement on the final assembly. This is known as tolerance analysis. To that end, existing methods, often based on modeling of the open kinematic chains in robotics, are classified as deterministic or statistical. These methods suppose that the assembled parts are not perfect with regard to the nominal geometry and are rigid. The rigidity of the parts implies that the places of contacts are regarded as points. The validation or the determination of a tolerance zone is therefore accomplished by a series of simulation in specific points subjected to assembly constraints. To overcome the limitations and difficulties of point based approaches, the paper proposes the unification of two existing models: the Jacobian’s matrix model, based on the infinitesimal modeling of open kinematic chains in robotics, and the tolerance zone representation model, using small displacement screws and constraints to establish the extreme limits between which points and surfaces can vary. The approach also uses interval algebra as a novel method to take tolerance boundaries into account in tolerance analysis. The approach has been illustrated on a simple two parts assembly, nevertheless demonstrating the capability of the method to handle three-dimensional geometry. The results are then validated geometrically, showing the overall soundness of the approach.

Study on Algorithm for Grid Subdivision and Encryption Based on Technology of Three Dimensional Geological Modeling

2013 ◽  
Vol 336-338 ◽  
pp. 1416-1421
Author(s):  
Wei He ◽  
Wen Li Wu
Keyword(s):  
Cross Sections ◽  
Optimal Path ◽  
Three Dimensional ◽  
Surrounding Rock ◽  
Geological Modeling ◽  
Survey Area ◽  
Uniform Size ◽  
3D Geological Modeling ◽  
3D Space ◽  
The Relationship

To achieve 3D grid models which have a non-uniform size and varying properties, we proposed the algorithm of grid subdivision and encryption by human-computer interaction. This algorithm was the technology based on 3D geological modeling, and achieving process has following three steps. Firstly, we converted many 2D cross sections to 3D space, and reconstructed 3D vector models using the algorithm of optimal path suture, and set the property of abnormal body and surrounding rock. Then, achieving 3D grids subdivided according to the relationship between the center of 3D grid and 3D vector models, the properties of 3D grids were determined. Finally, we encrypted grids in the survey area and expansion area, and modified the properties. The results show that the algorithm can realize the conversion from 3D vector models to 3D grid models, and this process is reliable and efficient.

A small displacement torsor model for 3D tolerance analysis of conical structures

2014 ◽  
Vol 229 (14) ◽  
pp. 2514-2523 ◽  
Author(s):  
Sun Jin ◽  
Hua Chen ◽  
Zhimin Li ◽  
Xinmin Lai
Keyword(s):  
Three Dimensional ◽  
Tolerance Analysis ◽  
Dimensional Euclidean Space ◽  
Small Displacement ◽  
Analysis Method ◽  
Tolerance Zone ◽  
Geometric Tolerances ◽  
Small Displacement Torsor ◽  
Conical Surfaces ◽  
Conical Structures

The small displacement torsor model is a classic three-dimensional tolerance analysis method. It uses three translational vectors and three rotational vectors to represent tolerance information in three-dimensional Euclidean space. However, the target features of this model mainly focused on planes and cylinders in previous studies. Little attention is invested to conical features and their joints which are used widely and more complex than the planar and cylindrical features. The objective of this article is to present a three-dimensional mathematical method of tolerance representation about conical surfaces and their joints based on the small displacement torsor model, and propose a mathematical model of variations and constraint relations of components of the small displacement torsor for conical surfaces caused by geometric tolerances limited by its tolerance zone. In addition, a simple example involving conical structures is used to demonstrate three-dimensional conical tolerance propagation. Both deterministic and statistical results are obtained by this model.

scholarly journals Design of urban furniture to enhance the soundscape: A case study

2018 ◽  
Vol 25 (1) ◽  
pp. 61-75 ◽  
Author(s):  
Gioia Fusaro ◽  
Francesco D’Alessandro ◽  
Giorgio Baldinelli ◽  
Jian Kang
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Open Spaces ◽  
Three Dimensional Printing ◽  
Historical Heritage ◽  
Environmental Feasibility ◽  
The Relationship ◽  
Dimensional Printing

In modern urban scenarios, all the aspects of the historical heritage, including public open spaces and ancient buildings, have to meet the high increase of density of infrastructures and constructions, with the consequent change of visual and sound environments. This in turn affects people’s quality of life. Because of the growing interest on this problem, this study investigates the relationship between soundscape and design solutions for urban furniture, considering technical and environmental feasibility of the designing process, from the materials characteristics, to the acoustic and psychoacoustic impact of the tool on the user. The process includes the acoustic suitability of three-dimensional printing materials, the suitability of acoustic design using software simulation, the experimental assessment of the performance of the three-dimensional printed prototype and the statistical evaluation of the chosen studying parameters and conditions. This article describes all the stages of the designing process, with a focus on the study of shapes and volumes of the prototype and on its impact on the user’s perception. FEM simulations and experimental tests performed in a semi-anechoic chamber allowed to validate the design process. These analyses proved that the designed prototype of urban furniture can not only positively influence the physical environment but also the psychoacoustic perception of it.

scholarly journals Media crisis and disinformation: the participation of digital newspapers in the dissemination of a denialist hoax

2021 ◽  
Author(s):  
Lorena Cano-Orón ◽  
Dafne Calvo ◽  
Germán Llorca-Abad ◽  
Rosanna Mestre-Pérez
Keyword(s):  
Digital Media ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Attention Economy ◽  
Media Ecosystem ◽  
The Media ◽  
Current Context ◽  
The Relationship ◽  
Digital Newspapers

Disinformation is a communicative phenomenon that frequently feeds on political or electoral topics, as well as other aspects of our reality. This research takes as a case study the coverage given by the Spanish digital media to a hoax broadcast during the Filomena storm in 2021 that insisted that the snow was plastic. The purpose of this work is to analyze the instrumentalization of fake information as an expression of the information media crisis in the current context of disinformation. We set out four specific objectives: (SO1) to study the spread of the hoax through the media, (SO2) to analyze the construction of headlines in the news pieces, (SO3) to investigate the treatment of the hoax in the content of the pieces, and (SO4) to analyze the sources used in the pieces. To reflect on this phenomenon, we propose a three-dimensional model (structural, economic, and pragmatic) aimed at clarifying the relationship between the logic of the spread of hoaxes on the Internet and the role played by traditional media in their diffusion. The methodology used combines workflow techniques of digital methods with quantitative and content analyses. The results reveal the appropriation of certain communication strategies by digital newspapers aimed at obtaining visits. We conclude that the Spanish media, by adapting to the dynamics of disinformation irresponsibly encouraged by the attention economy, subscribe to and reinforce the crisis of credibility faced by the media ecosystem.

Deciphering the Influence of Product Shape on Consumer Judgments Through Geometric Abstraction

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Gunay Orbay ◽  
Luoting Fu ◽  
Levent Burak Kara
Keyword(s):  
Three Dimensional ◽  
Strongly Correlated ◽  
Visual Elements ◽  
Production Models ◽  
Geometric Representations ◽  
3D Computer Model ◽  
Shape Characteristics ◽  
Geometric Elements ◽  
The Relationship

Understanding and tailoring the visual elements of a developing product to evoke desired perceived qualities and a positive response from the consumer is a key challenge in industrial design. To date, computational approaches to assist this process have either relied on stiff geometric representations, or focused on superficial features that exclude often elusive shape characteristics. In this work, we aim to study the relationship between product geometry and consumers' qualitative judgments through a visual decomposition and abstraction of existing products. At the heart of our investigation is a shape analysis method that produces a spectrum of abstractions for a given three-dimensional (3D) computer model. Our approach produces a hierarchical simplification of an end product, whereby consumer response to geometric elements can be statistically studied across different products, as well as across the different abstractions of one particular product. The results of our case study show that consumer judgments formed by coarse product “impressions” are strongly correlated with those evoked by the final production models. This outcome highlights the importance of early geometric explorations and assessments before committing to detailed design efforts.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

Sign in / Sign up

Export Citation Format

Share Document